JP4649812B2 - Image signal processing apparatus, image signal processing method and image display apparatus using the same, program for executing each image signal processing method, and computer-readable medium storing the program - Google Patents

Description

【００３６】
そして、動きクラス検出回路１２５では、上述したように算出された平均値ＡＶが１個または複数個のしきい値と比較されて動きクラスのクラス情報ＭＶが得られる。例えば、３個のしきい値ｔｈ１，ｔｈ２，ｔｈ３（ｔｈ１＜ｔｈ２＜ｔｈ３）が用意され、４つの動きクラスを検出する場合、ＡＶ≦ｔｈ１のときはＭＶ＝０、ｔｈ１＜ＡＶ≦ｔｈ２のときはＭＶ＝１、ｔｈ２＜ＡＶ≦ｔｈ３のときはＭＶ＝２、ｔｈ３＜ＡＶのときはＭＶ＝３とされる。
【００３７】
また、画像信号処理部１１０は、空間クラス検出回路１２４より出力される空間クラスのクラス情報としての再量子化コードｑｉと、動きクラス検出回路１２５より出力される動きクラスのクラス情報ＭＶに基づき、作成すべきＨＤ信号（１０５０ｉ信号）の画素データ（注目位置の画素データ）が属するクラスを示すクラスコードＣＬを得るためのクラス合成回路１２６を有している。
【００３８】
このクラス合成回路１２６では、（３）式によって、クラスコードＣＬの演算が行われる。なお、（３）式において、Ｎａは空間クラスタップのデータ（ＳＤ画素データ）の個数、ＰはＡＤＲＣにおける再量子化ビット数を示している。
【００３９】
【数２】

【００４０】
また、画像信号処理部１１０は、係数メモリ１３１を有している。この係数メモリ１３１は、後述する推定予測演算回路１２７で使用される推定式の係数データを格納するものである。この係数データは、ＳＤ信号（５２５ｉ信号）を、ＨＤ信号（１０５０ｉ信号）に変換する際に使用する情報である。この係数メモリ１３１には、クラス合成回路１２６より出力されるクラスコードＣＬおよび後述する係数選択回路１３３より出力される係数選択信号ＳＥＬが、読み出しアドレス情報として供給される。この係数メモリ１３１からはクラスコードＣＬおよび係数選択信号ＳＥＬに対応した係数データｗｉが読み出され、推定予測演算回路１２７に供給される。
【００４１】
また、画像信号処理部１１０は、情報メモリバンク１３２を有している。本実施の形態においては、パラメータＱは０〜８の間で変更可能とされる。情報メモリバンク１３２には、パラメータＱの０，１，・・・，８の各離散値に対応した、９つの解像度における各クラスの係数データが予め蓄えられている。ここで、パラメータＱの値が大きくなるほど解像度が高くなっていくものとする。この９つの解像度に対応する係数データの生成方法については後述する。
【００４２】
なお、上述したように、５２５ｉ信号を１０５０ｉ信号に変換する場合、奇数、偶数のそれぞれのフィールドにおいて、５２５ｉ信号の１画素に対応して１０５０ｉ信号の４画素を得る必要がある。そのため、ある解像度におけるあるクラスの係数データは、奇数、偶数のそれぞれのフィールドにおける１０５０ｉ信号を構成する２×２の単位画素ブロック内の４画素に対応した係数データからなっている。この２×２の単位画素ブロック内の４画素は、５２５ｉ信号の画素に対応して互いに異なる位相関係になっている。この複数の解像度に対応する係数データの生成方法については後述する。
【００４３】
上述したように、ユーザは、リモコン送信機２００の操作部において、アップキーおよびダウンキーの押圧操作、またはジョグダイヤル等のつまみの回転操作をすることで、システムコントローラ１０１から画像信号処理部１１０に供給されるパラメータＱの値を変更できる。情報メモリバンク１３２には、そのパラメータＱが供給され、この情報メモリバンク１３２から係数メモリ１３１には、パラメータＱの値の近傍に位置する２つの離散値ｍ，ｍ＋１（ｍ＝０，１，・・・，７）に対応した係数データがロードされる。
【００４４】
すなわち、０≦Ｑ≦１であるときはＱ＝０，１に対応した係数データが、１＜Ｑ≦２であるときはＱ＝１，２に対応した係数データが、２＜Ｑ≦３であるときはＱ＝２，３に対応した係数データが、３＜Ｑ≦４であるときはＱ＝３，４に対応した係数データが、４＜Ｑ≦５であるときはＱ＝４，５に対応した係数データが、５＜Ｑ≦６であるときはＱ＝５，６に対応した係数データが、６＜Ｑ≦７であるときはＱ＝６，７に対応した係数データが、７＜Ｑ≦８であるときはＱ＝７，８に対応した係数データが、情報メモリバンク１３２から係数メモリ１３１にロードされる。
【００４５】
また、画像信号処理部１１０は、係数選択信号ＳＥＬを発生する係数選択回路１３３を有している。この係数選択信号ＳＥＬは、上述したように係数メモリ１３１に読み出しアドレス情報として供給されるものであり、情報メモリバンク１３２から係数メモリ１３１にロードされて格納された、パラメータＱの２つの離散値に対応した係数データのうち一つの係数データを選択するために使用される。
【００４６】
図２は、係数選択回路１３３の構成を示している。この係数選択回路１３３は、特徴量検出部１４１、特徴量メモリ１４２、特徴量領域決定部１４３、領域検出部１４４および係数選択信号生成部１４５とからなっている。
【００４７】
特徴量検出部１４１は、バッファメモリ１０９に一時的に記憶される各フィールドのＳＤ信号（５２５ｉ信号）を構成するＳＤ画素毎に特徴量ＣＨを検出するものである。本実施の形態において、あるＳＤ画素（着目画素）に対応した特徴量ＣＨは、そのＳＤ画素を中心とした所定サイズのブロック内のダイナミックレンジＤＲとアクティビティＡＣＴの乗算値の平方根をとった値（√（ＤＲ×ＡＣＴ）とする。ブロックサイズは、例えば５×５とする。
【００４８】
ダイナミックレンジＤＲは、図３に示すように、着目画素を中心とした５×５のブロック内に含まれる２５個のＳＤ画素のデータｘ_i-2,j+2〜ｘ_i+2,j-2の中で、最大値をＭＡＸ、最小値をＭＩＮとするとき、（４）式で定義される。図３では、着目画素の座標を（ｉ，ｊ）としている。
ＤＲ＝ＭＡＸ−ＭＩＮ ・・・（４）
【００４９】
アクティビティＡＣＴは、図４に示すように、着目画素の座標を（ｉ，ｊ）とし、この着目画素を中心とした５×５のブロック内に含まれる２５個のＳＤ画素のデータをｘ_i-2,j+2〜ｘ_i+2,j-2とするとき、（５）式で定義される。ここで、ｉ₁＝ｉ−２，・・・，ｉ＋１、ｉ₂＝ｉ−２，・・・，ｉ＋２、ｊ₁＝ｊ−２，・・・，ｊ＋２、ｊ₂＝ｊ−２，・・・，ｊ＋１である。
【００５０】
【数３】

【００５１】
図５は、ダイナミックレンジＤＲおよびアクティビティＡＣＴによる検出部分のモデルを示している。ダイナミックレンジＤＲを用いると、図５中の右上の太線で示したように、画像の輪郭が検出される。一方、アクティビティＡＣＴを用いると、図５中の右下の太い線で示したように、画像の低周波領域に囲まれた高周波領域が検出される。特徴量ＣＨは上述したように、√（ＤＲ×ＡＣＴ）で定義されるため、この特徴量ＣＨを用いると、画像の輪郭および画像の低周波領域に囲まれた高周波領域の両方が検出されることとなる。
【００５２】
上述したように、５２５ｉ信号を１０５０ｉ信号に変換する場合、奇数、偶数のそれぞれのフィールドにおいて、５２５ｉ信号の１画素に対応して、１０５０ｉ信号の４画素を注目画素として、推定式で得るものである。したがって、特徴量検出部１４１にてＳＤ信号（５２５ｉ信号）を構成する各１画素に対応した特徴量ＣＨを検出するということは、ＨＤ信号（１０５０ｉ信号）を構成する各４画素（注目画素）の周辺における高周波成分量に関係する特徴量ＣＨを検出していることになる。
【００５３】
特徴量検出部１４１は、バッファメモリ１０９に記憶されるあるフィールドのＳＤ信号に対する特徴量ＣＨの検出処理を例えば垂直ブランキング期間で行う。特徴量メモリ１４２は、特徴量検出部１４１においてある垂直ブランキング期間に検出される１フィールド分の各ＳＤ画素に対応した特徴量ＣＨを格納するものである。
【００５４】
また、特徴量領域決定部１４３は、特徴量メモリ１４２に格納された、あるフィールドの全ＳＤ画素に対応する特徴量ＣＨを用いて、特徴量ＣＨの最小値から最大値までの範囲を４領域に分割して４つの特徴量領域を決定するものである。特徴量領域決定部１４３は、この特徴量領域の決定処理を垂直ブランキング期間で行う。この場合、全ＳＤ画素に対応する特徴量ＣＨのうち各特徴量領域に含まれる個数が略等しくなるように、４つの特徴量領域が決定される。
【００５５】
図６は、全ＳＤ画素に対応する特徴量ＣＨのヒストグラムモデルを示している。ＣＨminは特徴量ＣＨの最小値、ＣＨmaxは特徴量ＣＨの最大値を示している。Ｒａ，Ｒｂ，Ｒｃ，Ｒｄは４つの特徴量領域であり、Ｎａ，Ｎｂ，Ｎｃ，Ｎｄは全ＳＤ画素に対応する特徴量ＣＨのうち各特徴量領域に含まれる個数を示している。この場合、個数Ｎａ，Ｎｂ，Ｎｃ，Ｎｄが略等しくなるように、特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄが決定されることとなる。
【００５６】
ここで、特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄの意義について考えてみる。Ｒａ，Ｒｂ，Ｒｃ，Ｒｄの順に特徴量ＣＨが大きく、高域成分量が多いことから、画面全体で同じ解像度を得るための係数データを用いてＳＤ画素データからＨＤ画素データを生成する場合、Ｒｄ側の特徴量領域内の特徴量ＣＨが検出される箇所ほど不適切な解像度となりやすい。図７のａ，ｂ，ｃ，ｄは、それぞれＲａ，Ｒｂ，Ｒｃ，Ｒｄの特徴量領域内の特徴量ＣＨが検出される画面内の箇所を示している。これら各箇所における不適切な解像度となる度合い（破綻度合い）をｐa，ｐb，ｐc，ｐdとすると、ｐa＜ｐb＜ｐc＜ｐdの関係となる。
【００５７】
領域検出部１４４は、特徴量検出部１４１においてある垂直ブランキング期間に検出されて特徴量メモリ１４２に格納された各ＳＤ画素に対応する特徴量ＣＨを、続く垂直有効走査期間で順次取り出し、各ＳＤ画素に対応する特徴量ＣＨが、上述した特徴量領域決定部１４３で決定された特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄのいずれに含まれるかを検出し、その検出情報ＤＥＴを出力するものである。
【００５８】
係数選択信号生成部１４５は、領域検出部１４４からの検出情報ＤＥＴと、システムコントローラ１０１から供給されるパラメータＱの値とから、係数選択信号ＳＥＬを生成するものである。
【００５９】
係数選択信号生成部１４５は、パラメータＱの各値に対応した、上述の特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄにおける解像度選択情報ＲＥＳが格納された格納手段としてのＲＯＭ（read only memory）１４６を持っている。
【００６０】
図８は、ＲＯＭ１４６内に格納された解像度選択情報ＲＥＳを模式的に表したものである。
この図において、「ａ」が記載された範囲（第１の範囲）では、特徴量ＣＨが特徴量領域Ｒａに含まれるときＲＥＳ＝１であり、特徴量ＣＨが特徴量領域Ｒｂ，Ｒｃ，Ｒｄに含まれるときＲＥＳ＝０であることを意味し、「ａ，ｂ」が記載された範囲（第２の範囲）では、特徴量ＣＨが特徴量領域Ｒａ，Ｒｂに含まれるときＲＥＳ＝１であり、特徴量ＣＨが特徴量領域Ｒｃ，Ｒｄに含まれるときＲＥＳ＝０であることを意味し、「ａ，ｂ，ｃ」が記載された範囲（第３の範囲）では、特徴量ＣＨが特徴量領域Ｒａ，Ｒｂ，Ｒｃに含まれるときＲＥＳ＝１であり、特徴量ＣＨが特徴量領域Ｒｄに含まれるときＲＥＳ＝０であることを意味し、「ａ，ｂ，ｃ，ｄ」が記載された範囲（第４の範囲）では、特徴量ＣＨが特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄのいずれに含まれるときでもＲＥＳ＝１であることを意味する。
【００６１】
また、この図において、ｉ＜Ｑ≦（ｉ＋０．２５）は第１の範囲に該当し、（ｉ＋０．２５）＜Ｑ≦（ｉ＋０．５）は第２の範囲に該当し、（ｉ＋０．５）＜Ｑ≦（ｉ＋０．７５）は第３の範囲に該当し、（ｉ＋０．７５）＜Ｑ≦（ｉ＋１）は第４の範囲に該当する。ここで、ｉ＝０，１，・・・，７である。なお、Ｑ＝０であるときは、特徴量ＣＨが特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄのいずれに含まれるときでもＲＥＳ＝０である。
【００６２】
係数選択信号生成部１４５は、領域検出部１４４からの検出情報ＤＥＴと、システムコントローラ１０１から供給されるパラメータＱの値に対応した解像度選択情報ＲＥＳをＲＯＭ１４６より取り出し、この解像度選択情報ＲＥＳを係数選択信号ＳＥＬとして出力する。例えば、パラメータＱの値が０．４で、検出情報ＤＥＴが特徴量ＣＨが特徴量領域Ｒａに含まれていることを表しているとき、ＲＯＭ１４６よりＳＥＬ＝１が取り出され、係数選択信号ＳＥＬとして１が出力される。
【００６３】
この係数選択信号生成部１４５より出力される係数選択信号ＳＥＬが、係数選択回路１３３の出力ともなる。このように、係数選択回路１３３より出力される係数選択信号ＳＥＬは、上述したように係数メモリ１３１に読み出しアドレス情報として供給される。係数メモリ１３１（図１参照）には上述したように情報メモリバンク１３２からパラメータＱの値の近傍に位置する２つの離散値ｍ，ｍ＋１（ｍ＝０，１，・・・，７）に対応した係数データがロードされるが、ＳＥＬ＝０であるときは離散値ｍに対応した係数データが読み出し対象となり、ＳＥＬ＝１であるときは離散値ｍ＋１に対応した係数データが読み出し対象となる。
【００６４】
図１に戻って、また、画像信号処理部１１０は、第１のタップ選択回路１２１で選択的に取り出される予測タップのデータ（ＳＤ画素データ）ｘｉと、係数メモリ１３１より読み出される係数データｗｉとから、作成すべきＨＤ信号の画素データ（注目位置の画素データ）ｙを演算する推定予測演算回路１２７を有している。
【００６５】
上述したように、ＳＤ信号（５２５ｉ信号）をＨＤ信号（１０５０ｉ信号）に変換する際には、ＳＤ信号の１画素に対してＨＤ信号の４画素を得る必要があることから、この推定予測演算回路１２７では、ＨＤ信号を構成する２×２の単位画素ブロック毎に、ＨＤ画素データが生成される。
【００６６】
すなわち、この推定予測演算回路１２７には、第１のタップ選択回路１２１より単位画素ブロック内の４画素のデータ（注目位置の画素データ）に対応した予測タップのデータｘｉと、係数メモリ１３１よりその単位画素ブロックを構成する４画素に対応した係数データｗｉとが供給され、単位画素ブロックを構成する４画素のデータｙ₁〜ｙ₄は、それぞれ個別に（６）式の推定式で演算される。
【００６７】
【数４】

【００６８】
また、画像信号処理部１１０は、推定予測演算回路１２７より順次出力される単位画素ブロックを構成する４画素のデータｙ₁〜ｙ₄を、線順次化して１０５０ｉ信号のフォーマットで出力する後処理回路１２８を有している。
【００６９】
次に、画像信号処理部１１０の動作を説明する。
バッファメモリ１０９に記憶されているＳＤ信号（５２５ｉ信号）より、第２のタップ選択回路１２２で、作成すべきＨＤ信号（１０５０ｉ信号）を構成する単位画素ブロック内の４画素（注目位置の画素）の周辺に位置する空間クラスタップのデータ（ＳＤ画素データ）が選択的に取り出される。この第２のタップ選択回路１２２で選択的に取り出される空間クラスタップのデータ（ＳＤ画素データ）は空間クラス検出回路１２４に供給される。この空間クラス検出回路１２４では、空間クラスタップのデータとしての各ＳＤ画素データに対してＡＤＲＣ処理が施されて空間クラス（主に空間内の波形表現のためのクラス分類）のクラス情報としての再量子化コードｑｉが得られる（（１）式参照）。
【００７０】
また、バッファメモリ１０９に記憶されているＳＤ信号（５２５ｉ信号）より、第３のタップ選択回路１２３で、作成すべきＨＤ信号（１０５０ｉ信号）を構成する単位画素ブロック内の４画素（注目位置の画素）の周辺に位置する動きクラスタップのデータ（ＳＤ画素データ）が選択的に取り出される。この第３のタップ選択回路１２３で選択的に取り出される動きクラスタップのデータ（ＳＤ画素データ）は動きクラス検出回路１２５に供給される。この動きクラス検出回路１２５では、動きクラスタップのデータとしての各ＳＤ画素データより動きクラス（主に動きの程度を表すためのクラス分類）のクラス情報ＭＶが得られる。
【００７１】
このクラス情報ＭＶと上述した再量子化コードｑｉはクラス合成回路１２６に供給される。このクラス合成回路１２６では、これらクラス情報ＭＶと再量子化コードｑｉとから、作成すべきＨＤ信号（１０５０ｉ信号）を構成する単位画素ブロック毎に、その単位画素ブロック内の４画素のデータ（注目位置の画素データ）が属するクラスを示すクラスコードＣＬが得られる（（３）式参照）。そして、このクラスコードＣＬは、係数メモリ１３１に読み出しアドレス情報として供給される。
【００７２】
また、バッファメモリ１０９に記憶されているＳＤ信号（５２５ｉ信号）より、係数選択回路１３３で、作成すべきＨＤ信号（１０５０ｉ信号）を構成する単位画素ブロック毎にその単位画素ブロック内の４画素（注目位置の画素）に対応する係数選択信号ＳＥＬが生成される。
【００７３】
すなわち、図２に示すように、バッファメモリ１０９に記憶されるＳＤ信号（５２５ｉ信号）が係数選択回路１３３の特徴量検出部１４１に供給され、この特徴量検出部１４１では各フィールドのＳＤ信号を構成するＳＤ画素毎に特徴量ＣＨ＝√（ＤＲ×ＡＣＴ）が検出される。そして、特徴量検出部１４１で、ある垂直ブランキング期間で検出される１フィールド分のＳＤ信号に対応する特徴量ＣＨは特徴量メモリ１４２に格納される。
【００７４】
上述したように、５２５ｉ信号を１０５０ｉ信号に変換する場合、奇数、偶数のそれぞれのフィールドにおいて、５２５ｉ信号の１画素に対応して、１０５０ｉ信号の４画素を注目画素として、推定式で得るものである。したがって、特徴量検出部１４１にてＳＤ信号（５２５ｉ信号）を構成する各１画素に対応した特徴量ＣＨを検出するということは、ＨＤ信号（１０５０ｉ信号）を構成する各４画素（注目画素）に対応した特徴量ＣＨを検出していることになる。
【００７５】
また、特徴量領域決定部１４３において、ある垂直ブランキング期間に特徴量メモリ１４２に格納された１フィールド分のＳＤ信号に対応する特徴量ＣＨが使用されて、全ＳＤ画素に対応する特徴量ＣＨの最小値ＣＨminから最大値ＣＨmaxまでの範囲を４領域に分割して４つの特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄが決定される（図６参照）。この場合、全ＳＤ画素に対応する特徴量ＣＨのうち各特徴量領域に含まれる個数が略等しくなるように４つの特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄの範囲が決定される。
【００７６】
そして、ある垂直ブランキング期間に特徴量メモリ１４２に格納された１フィールド分のＳＤ信号が、続く垂直有効走査期間で順次取り出されて領域検出部１４４に供給され、各ＳＤ画素に対応する特徴量ＣＨが、上述した特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄのいずれに含まれるかが検出される。この検出情報ＤＥＴは係数選択信号生成部１４５に供給される。
【００７７】
この係数選択信号生成部１４５には、さらにシステムコントローラ１０１からパラメータＱが供給される。係数選択信号生成部１４５が持っているＲＯＭ１４６には、上述したように、パラメータＱの各値に対応した、特徴量領域Ｒａ，Ｒｂ，Ｒｃ，Ｒｄにおける解像度選択情報ＲＥＳが格納されている。係数選択信号生成部１４５では、領域検出部１４４からの検出情報ＤＥＴと、システムコントローラ１０１から供給されるパラメータＱの値に対応した解像度選択情報ＲＥＳがＲＯＭ１４６より取り出される。
【００７８】
そして、この取り出された係数選択情報ＲＥＳが、係数選択信号生成部１４５、従って係数選択回路１３３の出力となる。したがって、係数選択回路１３３からは、作成すべきＨＤ信号（１０５０ｉ信号）を構成する単位画素ブロック毎にその単位画素ブロック内の４画素（注目位置の画素）に対応する係数選択信号ＳＥＬが出力されることとなる。この係数選択信号ＳＥＬは、係数メモリ１３１に読み出しアドレス情報として供給される。
【００７９】
係数メモリ１３１には、情報メモリバンク１３２から、パラメータＱの値の近傍に位置する２つの離散値ｍ，ｍ＋１（ｍ＝０，１，・・・，７）に対応した各クラスの係数データがロードされている。このような係数データのロード動作は、例えば、パラメータＱの値が変更があって、係数メモリ１３１に格納すべき係数データの変更が必要となる場合に行われる。
【００８０】
係数メモリ１３１に上述したようにクラスコードＣＬおよび係数選択信号ＣＬが読み出しアドレス情報として供給されることで、この係数メモリ１３１からクラスコードＣＬに対応し、かつ係数選択信号ＳＥＬに対応した係数データｗｉが読み出されて推定予測演算回路１２７に供給される。この場合、ＳＥＬ＝０であるときは離散値ｍに対応した係数データが読み出され、ＳＥＬ＝１であるときは離散値ｍ＋１に対応した係数データが読み出される。
【００８１】
また、第１のタップ選択回路１２１では、バッファメモリ１０９に記憶されているＳＤ信号（５２５ｉ信号）より、作成すべきＨＤ信号（１０５０ｉ信号）を構成する単位画素ブロック内の４画素（注目位置の画素）の周辺に位置する予測タップのデータ（ＳＤ画素データ）が選択的に取り出される。この第１のタップ選択回路１２１で選択的に取り出される予測タップのデータ（ＳＤ画素データ）ｘｉは推定予測演算回路１２７に供給される。
【００８２】
推定予測演算回路１２７では、予測タップのデータ（ＳＤ画素データ）ｘｉと、係数メモリ１３１より読み出される４画素分の係数データｗｉとから、作成すべきＨＤ信号を構成する単位画素ブロック内の４画素のデータｙ₁〜ｙ₄がそれぞれ個別に演算される（（６）式参照）。そして、この推定予測演算回路１２７より順次出力される４画素のデータｙ₁〜ｙ₄は、後処理回路１２８に供給される。この後処理回路１２８は、推定予測演算回路１２７より順次出力される４画素のデータｙ₁〜ｙ₄を線順次化し、１０５０ｉ信号のフォーマットで出力する。つまり、この後処理回路１２８からは、ＨＤ信号としての１０５０ｉ信号が出力される。
【００８３】
上述したように、係数メモリ１３１にはシステムコントローラ１０１より供給されるパラメータＱの値の近傍に位置する２つの離散値ｍ，ｍ＋１（ｍ＝０，１，・・・，７）に対応した各クラスの係数データが情報メモリバンク１３２よりロードされる。そのため、ユーザがリモコン送信機２００を操作してパラメータＱの値を変更すると、それに伴って係数メモリ１３１に格納される係数データも変更され、推定予測演算回路１２７ではＨＤ信号の画素データがパラメータＱの値に対応して生成される。したがって、ユーザは、パラメータＱの値を変更することで、ＨＤ信号による画像の解像度を、従来のコントラストやシャープネスの調整のように、所望の値に任意に調整できる。
【００８４】
また、係数メモリ１３１に格納されるパラメータＱの値の近傍に位置する２つの離散値ｍ，ｍ＋１（ｍ＝０，１，・・・，７）に対応した各クラスの係数データのうち、推定予測演算回路１２７で実際にＨＤ信号の画素データを生成する際に使用する係数データが、係数選択回路１３３で生成される係数選択信号ＳＥＬに基づいて決定される。すなわち、作成すべきＨＤ信号を構成する単位画素ブロック内の４画素（注目位置の画素）の周辺における特徴量ＣＨが不適切な解像度となる度合い（破綻度合い）がいかなる特徴量領域に含まれるか、およびパラメータＱの値がｍからｍ＋１までのいずれにあるかに応じて、離散値ｍに対応した係数データを使用するか、離散値ｍ＋１に対応した係数データを使用するか決定される。因に、離散値ｍ＋１に対応した係数データは、離散値ｍに対応した係数データより、高い解像度を得るためのものである。
【００８５】
例えば、パラメータＱの値がｍに近くなる程、特徴量ＣＨが不適切な解像度となる度合い（破綻度合い）が低い特徴量領域に含まれる場合だけ、離散値ｍ＋１に対応した係数データが使用される（図８参照）。これにより、不適切な解像度となる度合い（破綻度合い）が高い特徴量領域に特徴量ＣＨが含まれる箇所が、不適切な解像度となることを防止でき、ＨＤ信号による画像の画質の向上を図ることができる。
【００８６】
図９は、画面内の各箇所ａ〜ｄが、図７で説明したと同様の状態にある場合において、パラメータＱの値がｍ〜ｍ＋１に変化した場合に、各箇所で離散値ｍあるいは離散値ｍ＋１のいずれに対応した係数データが使用されるかを示したものである。
【００８７】
Ｑ＝ｍである場合には、図９（ａ）に示すように、ａ〜ｄの全ての箇所で離散値ｍに対応した係数データｗmが使用される。ｍ＜Ｑ≦ｍ＋０．２５である場合には、図９（ｂ）に示すように、ａの箇所で離散値ｍ＋１に対応した係数データｗm+1が使用され、ｂ〜ｄの箇所で離散値ｍに対応した係数データｗmが使用される。ｍ＋０．２５＜Ｑ≦ｍ＋０．５である場合には、図９（ｃ）に示すように、ａ，ｂの箇所で離散値ｍ＋１に対応した係数データｗm+1が使用され、ｃ，ｄの箇所で離散値ｍに対応した係数データｗmが使用される。ｍ＋０．５＜Ｑ≦ｍ＋０．７５である場合には、図９（ｄ）に示すように、ａ〜ｃの箇所で離散値ｍ＋１に対応した係数データｗm+1が使用され、ｄの箇所で離散値ｍに対応した係数データｗmが使用される。さらに、ｍ＋０．７５＜Ｑ≦ｍ＋１である場合には、図９（ｅ）に示すように、ａ〜ｄの全て箇所で離散値ｍ＋１に対応した係数データｗm+1が使用される。
【００８８】
なお、上述実施の形態においては、注目画素の周辺における高周波成分量に関係する特徴量ＣＨとして√（ＤＲ×ＡＣＴ）で表されるものを使用したものであるが、これに限定されるものではない。この特徴量ＣＨとしては、同じ解像度を得るための係数データを使用してＨＤ信号を得る場合に、不適切な解像度となる度合い（破綻度合い）を段階的に分類できるものであればよい。
【００８９】
また、上述実施の形態においては、説明を簡単にするため、特徴量ＣＨの最小値ＣＨminから最大値ＣＨmaxまでの範囲を４領域に分割して４つの特徴量領域Ｒａ〜Ｒｄを決定し（図６参照）、またそれに対応してパラメータＱの各離散値の間を４つの範囲に分割した（図８参照）ものを示したが、これらの個数は実際にはもっと多くされ、例えば１０とされる。
【００９０】
また、上述実施の形態においては、全ＳＤ画素に対応する特徴量ＣＨのうち各特徴量領域に含まれる個数Ｎａ，Ｎｂ，Ｎｃ，Ｎｄが略等しくなるようにしたが、必ずしも等しくする必要はない。ただし、個数Ｎａ，Ｎｂ，Ｎｃ，Ｎｄを略等しくすることで、パラメータＱの値の変化に比例したＨＤ画像の解像度変化を期待できる。
【００９１】
次に、情報メモリバンク１３２に蓄積されるパラメータＱの０，１，・・・，８の各離散値に対応した、９つの解像度に対応する係数データの生成方法について説明する。この係数データは、予め学習によって生成されたものである。
【００９２】
まず、この学習方法について説明する。（６）式の推定式に基づく係数データｗi（ｉ＝１〜ｎ）を最小二乗法により求める例を示すものとする。一般化した例として、Ｘを入力データ、Ｗを係数データ、Ｙを予測値として、（７）式の観測方程式を考える。この（７）式において、ｍは学習データの数を示し、ｎは予測タップの数を示している。
【００９３】
【数５】

【００９４】
（７）式の観測方程式により収集されたデータに最小二乗法を適用する。この（７）式の観測方程式をもとに、（８）式の残差方程式を考える。
【００９５】
【数６】

【００９６】
（８）式の残差方程式から、各ｗiの最確値は、（９）式のｅ²を最小にする条件が成り立つ場合と考えられる。すなわち、（１０）式の条件を考慮すればよいわけである。
【００９７】
【数７】

【００９８】
つまり、（１０）式のｉに基づくｎ個の条件を考え、これを満たすｗ₁，ｗ₂，・・・，ｗ_nを算出すればよい。そこで、（８）式の残差方程式から、（１１）式が得られる。さらに、（１１）式と（７）式とから、（１２）式が得られる。
【００９９】
【数８】

【０１００】
そして、（８）式と（１２）式とから、（１３）式の正規方程式が得られる。
【０１０１】
【数９】

【０１０２】
（１３）式の正規方程式は、未知数の数ｎと同じ数の方程式を立てることが可能であるので、各ｗiの最確値を求めることができる。この場合、掃き出し法（Gauss-Jordanの消去法）等を用いて連立方程式を解くことになる。
【０１０３】
図１０は、上述した概念で係数データを生成する係数データ生成装置１５０を示している。この係数データ生成装置１５０は、教師信号としてのＨＤ信号（１０５０ｉ信号）が入力される入力端子１５１と、このＨＤ信号に対して水平および垂直の間引き処理を行って、生徒信号としてのＳＤ信号を得るＳＤ信号生成回路１５２とを有している。
【０１０４】
このＳＤ信号生成回路１５２には、パラメータＱが制御信号として供給される。このパラメータＱは、図１に示すテレビ受信機１００で、ユーザのリモコン送信機２００の操作によってシステムコントローラ１０１より出力されるパラメータＱに対応したものである。ただし、ここでは、パラメータＱの値として０，１，・・・，８の９つの離散値のみをとる。
【０１０５】
このＳＤ信号生成回路１５２では、パラメータＱの値に対応して、ＨＤ信号からＳＤ信号を生成する際に使用されるフィルタの水平および垂直の帯域が可変される。このフィルタは、例えば水平帯域を制限する１次元ガウシアンフィルタと垂直帯域を制限する１次元ガウシアンフィルタとから構成される。この１次元ガウシアンフィルタは、（１４）式で示される。
【０１０６】
【数１０】

【０１０７】
この場合、Ｑの離散的な値に対応して標準偏差σの値を段階的に変えることで、Ｑの離散的な値に対応した周波数特性を持つ１次元ガウシアンフィルタを得ることができる。この場合、パラメータＱの値が大きくなる程、水平および垂直の帯域が狭くなるようにされる。これにより、パラメータＱの値が大きくなる程、解像度の高いＨＤ信号を得るための係数データを生成できる。
【０１０８】
また、係数データ生成装置１５０は、ＳＤ信号生成回路１５２より出力されるＳＤ信号（５２５ｉ信号）より、ＨＤ信号（１０５０ｉ信号）における注目位置の周辺に位置する複数のＳＤ画素のデータを選択的に取り出して出力する第１〜第３のタップ選択回路１５３〜１５５を有している。これら第１〜第３のタップ選択回路１５３〜１５５は、上述した画像信号処理部１１０の第１〜第３のタップ選択回路１２１〜１２３と同様に構成される。
【０１０９】
また、係数データ生成装置１５０は、第２のタップ選択回路１５４で選択的に取り出される空間クラスタップのデータ（ＳＤ画素データ）のレベル分布パターンを検出し、このレベル分布パターンに基づいて空間クラスを検出し、そのクラス情報を出力する空間クラス検出回路１５７を有している。この空間クラス検出回路１５７は、上述した画像信号処理部１１０の空間クラス検出回路１２４と同様に構成される。この空間クラス検出回路１５７からは、空間クラスタップのデータとしての各ＳＤ画素データ毎の再量子化コードｑｉが空間クラスを示すクラス情報として出力される。
【０１１０】
また、係数データ生成装置１５０は、第３のタップ選択回路１５５で選択的に取り出される動きクラスタップのデータ（ＳＤ画素データ）より、主に動きの程度を表すための動きクラスを検出し、そのクラス情報ＭＶを出力する動きクラス検出回路１５８を有している。この動きクラス検出回路１５８は、上述した画像信号処理部１１０の動きクラス検出回路１２５と同様に構成される。この動きクラス検出回路１５８では、第３のタップ選択回路１５５で選択的に取り出される動きクラスタップのデータ（ＳＤ画素データ）からフレーム間差分が算出され、さらにその差分の絶対値の平均値に対してしきい値処理が行われて動きの指標である動きクラスが検出される。
【０１１１】
また、係数データ生成装置１５０は、空間クラス検出回路１５７より出力される空間クラスのクラス情報としての再量子化コードｑｉと、動きクラス検出回路１５８より出力される動きクラスのクラス情報ＭＶに基づき、ＨＤ信号（１０５０ｉ信号）における注目位置の画素データが属するクラスを示すクラスコードＣＬを得るためのクラス合成回路１５９を有している。このクラス合成回路１５９も、上述した画像信号処理部１１０のクラス合成回路１２６と同様に構成される。
【０１１２】
また、係数データ生成装置１５０は、入力端子１５１に供給されるＨＤ信号より得られる注目位置の画素データとしての各ＨＤ画素データｙと、この各ＨＤ画素データｙにそれぞれ対応して第１のタップ選択回路１５３で選択的に取り出される予測タップのデータ（ＳＤ画素データ）ｘｉと、各ＨＤ画素データｙにそれぞれ対応してクラス合成回路１５９より出力されるクラスコードＣＬとから、クラス毎に、ｎ個の係数データｗｉを得るための正規方程式（（１３）式参照）を生成する正規方程式生成部１６０を有している。
【０１１３】
この場合、１個のＨＤ画素データｙとそれに対応するｎ個の予測タップ画素データとの組み合わせで上述した学習データが生成され、従って正規方程式生成部１６０では多くの学習データが登録された正規方程式が生成される。なお、図示せずも、第１のタップ選択回路１５３の前段に時間合わせ用の遅延回路を配置することで、この第１のタップ選択回路１５３から正規方程式生成部１６０に供給されるＳＤ画素データｘｉのタイミング合わせが行われる。
【０１１４】
また、係数データ生成装置１５０は、正規方程式生成部１６０でクラス毎に生成された正規方程式のデータが供給され、クラス毎に生成された正規方程式を解いて、各クラスの係数データｗｉを求める係数データ決定部１６１と、この求められた係数データｗｉを記憶する係数メモリ１６２とを有している。係数データ決定部１６１では、正規方程式が例えば掃き出し法などによって解かれて、係数データｗｉが求められる。
【０１１５】
図１０に示す係数データ生成装置１５０の動作を説明する。入力端子１５１には教師信号としてのＨＤ信号（１０５０ｉ信号）が供給され、そしてこのＨＤ信号に対してＳＤ信号生成回路１５２で水平および垂直の間引き処理が行われて生徒信号としてのＳＤ信号（５２５ｉ信号）が生成される。この場合、ＳＤ信号生成回路１５２には、パラメータＱが制御信号として供給され、パラメータＱの離散的な値に対応して、水平および垂直の帯域が段階的に変化した複数のＳＤ信号が順次生成されていく。
【０１１６】
このＳＤ信号（５２５ｉ信号）より、第２のタップ選択回路１５４で、ＨＤ信号（１０５０ｉ信号）における注目位置の周辺に位置する空間クラスタップのデータ（ＳＤ画素データ）が選択的に取り出される。この第２のタップ選択回路１５４で選択的に取り出される空間クラスタップのデータ（ＳＤ画素データ）は空間クラス検出回路１５７に供給される。この空間クラス検出回路１５７では、空間クラスタップのデータとしての各ＳＤ画素データに対してＡＤＲＣ処理が施されて空間クラス（主に空間内の波形表現のためのクラス分類）のクラス情報としての再量子化コードｑｉが得られる（（１）式参照）。
【０１１７】
また、ＳＤ信号生成回路１５２で生成されたＳＤ信号より、第３のタップ選択回路１５５で、ＨＤ信号における注目位置の周辺に位置する動きクラスタップのデータ（ＳＤ画素データ）が選択的に取り出される。この第３のタップ選択回路１５５で選択的に取り出される動きクラスタップのデータ（ＳＤ画素データ）は動きクラス検出回路１５８に供給される。この動きクラス検出回路１５８では、動きクラスタップのデータとしての各ＳＤ画素データより動きクラス（主に動きの程度を表すためのクラス分類）のクラス情報ＭＶが得られる。
【０１１８】
このクラス情報ＭＶと上述した再量子化コードｑｉはクラス合成回路１５９に供給される。このクラス合成回路１５９では、これらクラス情報ＭＶと再量子化コードｑｉとから、ＨＤ信号（１０５０ｉ信号）における注目位置の画素データが属するクラスを示すクラスコードＣＬが得られる（（３）式参照）。
【０１１９】
また、ＳＤ信号生成回路１５２で生成されるＳＤ信号より、第１のタップ選択回路１５３で、ＨＤ信号に係る注目画素の周辺に位置する予測タップのデータ（ＳＤ画素データ）が選択的に取り出される。そして、入力端子１５１に供給されるＨＤ信号より得られる注目位置の画素データとしての各ＨＤ画素データｙと、この各ＨＤ画素データｙにそれぞれ対応して第１のタップ選択回路１２１で選択的に取り出される予測タップのデータ（ＳＤ画素データ）ｘｉと、各ＨＤ画素データｙにそれぞれ対応してクラス合成回路１５９より出力されるクラスコードＣＬとから、正規方程式生成部１６０では、クラス毎に、ｎ個の係数データｗｉを生成するための正規方程式が生成される。
【０１２０】
そして、係数データ決定部１６１でその正規方程式が解かれ、各クラスの係数データｗｉが求められ、その係数データｗｉはクラス別にアドレス分割された係数メモリ１６２に記憶される。
【０１２１】
このように、図１０に示す係数データ生成装置１５０においては、図１の画像信号処理部１１０の情報メモリバンク１３２に記憶される各クラスの係数データｗｉを生成できる。この場合、ＳＤ信号生成回路１５２で生成されるＳＤ信号の水平および垂直の帯域をパラメータＱの値によって段階的に変化させることができる。そのため、パラメータＱの値を０，１，・・・，８に順次変化させてクラス毎の係数データｗｉを決定していくことで、パラメータＱの０，１，・・・，８の離散的な値に対応した各クラスの係数データｗｉを生成できる。
【０１２２】
なお、図１の画像信号処理部１１０における処理を、例えば図１１に示すような画像信号処理装置３００によって、ソフトウェアで実現することも可能である。
【０１２３】
まず、図１１に示す画像信号処理装置３００について説明する。この画像信号処理装置３００は、装置全体の動作を制御するＣＰＵ３０１と、このＣＰＵ３０１の動作プログラムや係数データ等が格納されたＲＯＭ（read only memory）３０２と、ＣＰＵ３０１の作業領域を構成するＲＡＭ（random access memory）３０３とを有している。これらＣＰＵ３０１、ＲＯＭ３０２およびＲＡＭ３０３は、それぞれバス３０４に接続されている。
【０１２４】
また、画像信号処理装置３００は、外部記憶装置としてのハードディスクドライブ（ＨＤＤ）３０５と、フロッピー（Ｒ）ディスク３０６をドライブするフロッピー（Ｒ）ディスクドライブ（ＦＤＤ）３０７とを有している。これらドライブ３０５，３０７は、それぞれバス３０４に接続されている。
【０１２５】
また、画像信号処理装置３００は、インターネット等の通信網４００に有線または無線で接続する通信部３０８を有している。この通信部３０８は、インタフェース３０９を介してバス３０４に接続されている。
【０１２６】
また、画像信号処理装置３００は、ユーザインタフェース部を備えている。このユーザインタフェース部は、リモコン送信機２００からのリモコン信号ＲＭを受信するリモコン信号受信回路３１０と、ＬＣＤ（liquid crystal display）等からなるディスプレイ３１１とを有している。受信回路３１０はインタフェース３１２を介してバス３０４に接続され、同様にディスプレイ３１１はインタフェース３１３を介してバス３０４に接続されている。
【０１２７】
また、画像信号処理装置３００は、ＳＤ信号を入力するための入力端子３１４と、ＨＤ信号を出力するための出力端子３１５とを有している。入力端子３１４はインタフェース３１６を介してバス３０４に接続され、同様に出力端子３１５はインタフェース３１７を介してバス３０４に接続される。
【０１２８】
ここで、上述したようにＲＯＭ３０２に処理プログラムや係数データ等を予め格納しておく代わりに、例えばインターネットなどの通信網４００より通信部３０８を介してダウンロードし、ハードディスクやＲＡＭ３０３に蓄積して使用することもできる。また、これら処理プログラムや係数データ等をフロッピー（Ｒ）ディスク３０６で提供するようにしてもよい。
【０１２９】
また、処理すべきＳＤ信号を入力端子３１４より入力する代わりに、予めハードディスクに記録しておき、あるいはインターネットなどの通信網４００より通信部３０８を介してダウンロードしてもよい。また、処理後のＨＤ信号を出力端子３１５に出力する代わり、あるいはそれと並行してディスプレイ３１１に供給して画像表示をしたり、さらにはハードディスクに格納したり、通信部３０８を介してインターネットなどの通信網４００に送出するようにしてもよい。
【０１３０】
図１２のフローチャートを参照して、図１１に示す画像信号処理装置３００における、ＳＤ信号よりＨＤ信号を得るため処理手順を説明する。
まず、ステップＳＴ１で、処理を開始し、ステップＳＴ２で、ＳＤ画素データをフィールド単位で入力する。このＳＤ画素データが入力端子３１４より入力される場合には、このＳＤ画素データをＲＡＭ３０３に一時的に格納する。また、このＳＤ画素データがハードディスクに記録されている場合には、ハードディスクドライブ３０７でこのＳＤ画素データを読み出し、ＲＡＭ３０３に一時的に格納する。そして、ステップＳＴ３で、入力ＳＤ画素データの全フィールドの処理が終わっているか否かを判定する。処理が終わっているときは、ステップＳＴ４で、処理を終了する。一方、処理が終わっていないときは、ステップＳＴ５に進む。
【０１３１】
ステップＳＴ５では、ユーザがリモコン送信機２００を操作して入力したパラメータＱの値を例えばＲＡＭ３０３より読み込む。そして、ステップＳＴ６で、読み込んだパラメータＱの値の近傍に位置する２つの離散値ｍ，ｍ＋１（ｍ＝０，１，・・・，７）に対応した各クラスの係数データを読み出し、ＲＡＭ３０３に一時的に格納する。
【０１３２】
次に、ステップＳＴ７で、ステップＳＴ２で入力された１フィールド分のＳＤ画素データより、各ＳＤ画素の特徴量ＣＨ（√（ＤＲ×ＡＣＴ））を求め、さらに各ＳＤ画素の特徴量ＣＨを用いて、４つの特徴量領域Ｒａ〜Ｒｄを決定する（図６参照）。なお、各ＳＤ画素の特徴量ＣＨは、後のステップでさらに使用するので、ＲＡＭ３０３に格納しておく。
【０１３３】
次に、ステップＳＴ８で、ステップＳＴ２で入力されたＳＤ画素データより、生成すべき各ＨＤ画素データ（注目画素データ）に対応して、クラスタップおよび予測タップの画素データを取得する。そして、ステップＳＴ９で、入力されたＳＤ画素データの全領域においてＨＤ画素データを得る処理が終了したか否かを判定する。処理が終了していないときは、ステップＳＴ１０に進む。
【０１３４】
このステップＳＴ１０では、生成すべき各ＨＤ画素データ（注目位置の画素データ）に対応するＳＤ画素の特徴量ＣＨが、上述の４つの特徴量領域Ｒａ〜Ｒｄのいずれに含まれるかを検出する。そして、ステップＳＴ１１で、その検出情報ＤＥＴとパラメータＱの値とから、離散値ｍ，ｍ＋１のいずれに対応した係数データを使用するかの係数選択信号ＳＥＬを生成する。
【０１３５】
次に、ステップＳＴ１２で、ステップＳＴ８で取得されたクラスタップのＳＤ画素データからクラスコードＣＬを生成する。そして、ステップ１３で、ステップＳＴ１１で生成された係数選択信号ＳＥＬで示される離散値に対応した係数データであって、ステップＳＴ１２で生成されたクラスコードＣＬで示されるクラスの係数データと、予測タップのＳＤ画素データを使用して、推定式（（６）式参照）により、パラメータＱの値に対応したＨＤ画素データを生成し、その後にステップＳＴ８に戻って、上述したと同様の処理を繰り返す。
【０１３６】
また、ステップＳＴ９で、処理が終了しているときは、ステップＳＴ２に戻り、次のフィールドのＳＤ画素データの入力処理に移る。
【０１３７】
このように、図１２に示すフローチャートに沿って処理をすることで、入力されたＳＤ信号を構成するＳＤ画素データを処理して、ＨＤ信号を構成するＨＤ画素データを得ることができる。上述したように、このように処理して得られたＨＤ信号は出力端子３１５に出力されたり、ディスプレイ３１１に供給されてそれによる画像が表示されたり、さらにはハードディスクドライブ３０５に供給されてハードディスクに記録されたりする。
【０１３８】
なお、上述実施の形態においては、ＨＤ信号を生成する際の推定式として線形一次方程式を使用したものを挙げたが、これに限定されるものではなく、例えば推定式として高次方程式を使用するものであってもよい。
【０１３９】
また、上述実施の形態においては、ＳＤ信号（５２５ｉ信号）をＨＤ信号（１０５０ｉ信号）に変換する例を示したが、この発明はそれに限定されるものでなく、推定式を使用して第１の画像信号を第２の画像信号に変換するその他の場合にも同様に適用できることは勿論である。
【０１４０】
【発明の効果】
この発明によれば、第１の情報信号を第２の情報信号に変換する際に、画像の解像度を示すパラメータの値に対応した係数データを用いて第２の画像信号における注目位置の画素データを算出するものであり、ユーザはパラメータの値を変更することで画像の解像度を所望の値に任意に調整できる。また、この発明によれば、第２の画像信号における注目位置の周辺における高周波成分量に関係する特徴量により、パラメータの値に対応した複数の係数データ候補から一つの係数データを選択して使用するものであり、第２の画像信号による画像に不適切な解像度となる箇所が発生することを防止でき、画質の向上を図ることができる。
【図面の簡単な説明】
【図１】実施の形態としてのテレビ受信機の構成を示すブロック図である。
【図２】係数選択回路の構成を示すブロック図である。
【図３】特徴量を構成するダイナミックレンジＤＲの説明に供する図である。
【図４】特徴量を構成するアクティビティＡＣＴの説明に供する図である。
【図５】ダイナミックレンジとアクティビティの検出部分のモデルを示す図である。
【図６】１フィールドの全ＳＤ画素に対応する特徴量のヒストグラムモデルを示す図である。
【図７】画面内の各特徴量領域内の箇所と破綻度合いの一例を示す図である。
【図８】係数選択信号生成部が持つＲＯＭ内の解像度選択情報を模式的に表した図である。
【図９】解像度を示すパラメータＱの値の変化に対する、画面内の各箇所で使用される係数データの変化を説明するための図である。
【図１０】係数データ生成装置の構成を示すブロック図である。
【図１１】ソフトウェアで実現するための画像信号処理装置の構成例を示すブロック図である。
【図１２】画像信号処理の手順を示すフローチャートである。
【図１３】５２５ｉ信号と１０５０ｉ信号の画素位置関係を説明するための図である。
【符号の説明】
１００・・・テレビ受信機、１０１・・・システムコントローラ、１０２・・・リモコン信号受信回路、１０５・・・受信アンテナ、１０６・・・チューナ、１０９・・・バッファメモリ、１１０・・・画像信号処理部、１１１・・・ディスプレイ部、１２１・・・第１のタップ選択回路、１２２・・・第２のタップ選択回路、１２３・・・第３のタップ選択回路、１２４・・・空間クラス検出回路、１２５・・・動きクラス検出回路、１２６・・・クラス合成回路、１２７・・・推定予測演算回路、１２８・・・後処理回路、１３１・・・係数メモリ、１３２・・・情報メモリバンク、１３３・・・係数選択回路、１４１・・・特徴量検出部、１４２・・・特徴量メモリ、１４３・・・特徴量領域決定部、１４４・・・領域検出部、１４５・・・係数選択信号生成部、１５０・・・係数データ生成装置、１５１・・・入力端子、１５２・・・ＳＤ信号生成回路、１５３・・・第１のタップ選択回路、１５４・・・第２のタップ選択回路、１５５・・・第３のタップ選択回路、１５７・・・空間クラス検出回路、１５８・・・動きクラス検出回路、１５９・・・クラス合成回路、１６０・・・正規方程式生成部、１６１・・・係数データ決定部、１６２・・・係数メモリ、２００・・・リモコン送信機、３００・・・画像信号処理装置、３０１・・・ＣＰＵ、３０２・・・ＲＯＭ、３０３・・・ＲＡＭ、３０４・・・バス、３０５・・・ハードディスクドライブ、３０７・・・フロッピー（Ｒ）ディスクドライブ、３０８・・・通信部、３０９，３１２，３１３，３１６，３１７・・・インタフェース、３１０・・・リモコン信号受信回路、３１１・・・ディスプレイ、３１４・・・入力端子、３１５・・・出力端子、４００・・・通信網[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image signal processing apparatus, an image signal processing method, an image display apparatus using the image signal processing apparatus, and an information providing medium that are suitable for application when converting, for example, an NTSC video signal to a high-definition video signal. Specifically, when the first image signal is converted into the second image signal, a feature amount related to the high-frequency component amount around the target position in the second image signal is detected, and a parameter indicating the resolution of the image is detected. By generating pixel data of the target position in the second image signal with reference to other detected feature quantities, it is possible to prevent occurrence of a portion having an inappropriate resolution in the image based on the second image signal. The present invention relates to an image signal processing apparatus and the like that are configured as described above.
[0002]
[Prior art]
Conventionally, for example, a format conversion for converting an SD (Standard Definition) signal called a 525i signal into an HD (High Definition) signal called a 1050i signal has been proposed. The 525i signal means an interlaced image signal having 525 lines, and the 1050i signal means an interlaced image signal having 1050 lines.
[0003]
FIG. 13 shows the pixel position relationship between the 525i signal and the 1050i signal. Here, a large dot is a pixel of a 525i signal, and a small dot is a pixel of a 1050i signal. In addition, pixel positions in odd fields are indicated by solid lines, and pixel positions in even fields are indicated by broken lines. When converting a 525i signal to a 1050i signal, it is necessary to obtain four pixels of the 1050i signal corresponding to one pixel of the 525i signal in each of the odd and even fields.
[0004]
Conventionally, when the pixel data of the 1050i signal is obtained from the pixel data of the 525i signal in order to perform the format conversion as described above, the coefficient data of the estimation formula corresponding to the phase of each pixel of the 1050i signal with respect to the pixel of the 525i signal is obtained. It has been proposed that pixel data of a 1050i signal is obtained by an estimation formula using the coefficient data stored in a memory.
[0005]
[Problems to be solved by the invention]
As described above, in the case of obtaining the pixel data of the 1050i signal by the estimation formula, the resolution of the image by the 1050i signal is fixed, and it is desired according to the image content or the like like the conventional adjustment of contrast, sharpness, etc. The resolution could not be achieved.
[0006]
Therefore, in the present invention, an image signal processing device or the like that allows a user to arbitrarily adjust the resolution of an image to a desired value and prevents occurrence of an inappropriate resolution in the image. The purpose is to provide.
[0007]
[Means for Solving the Problems]
An image signal processing apparatus according to the present invention is an image signal processing apparatus that converts a first image signal made up of a plurality of pixel data into a second image signal made up of a plurality of pixel data. Based on the first data selection means for selecting a plurality of first pixel data located around the target position in the second image signal, and the plurality of first pixels selected by the first data selection means Feature amount detecting means for detecting a feature amount related to the amount of high-frequency components in the vicinity of the position of interest based on the data; resolution parameter output means for outputting a parameter indicating the resolution of the image based on the second image signal; Pixel data for generating pixel data of the target position in the second image signal corresponding to the feature amount detected by the amount detection unit and the parameter output from the resolution parameter output unit. Those comprising a generation unit.
[0008]
For example, the pixel data generation means detects a plurality of representative resolutions corresponding to the parameters output from the resolution parameter output means with coefficient data candidate generation means for generating coefficient data candidates of the estimation formula, and feature quantity detection means. The coefficient data candidates generated by the resolution specifying means for specifying one of a plurality of representative resolutions and the coefficient data candidate generating means on the basis of the feature amount and the parameter output from the resolution parameter output means. Coefficient data selecting means for selecting coefficient data corresponding to the resolution specified by the resolution specifying means, and a plurality of second data located around the position of interest in the second image signal based on the first image signal. A second data selection means for selecting the pixel data of the second pixel data, and a plurality of second pixel data selected by the second data selection means. By using the coefficient data selected by the data selection means, and has a calculating means for calculating the pixel data of the target position based on the estimation equation.
[0009]
The image signal processing method according to the present invention is an image signal processing method for converting a first image signal composed of a plurality of pixel data into a second image signal composed of a plurality of pixel data, wherein the first image signal A first step of selecting a plurality of first pixel data located around a target position in the second image signal based on the signal, and a plurality of first pixel data selected in the first step. A second step of detecting a feature quantity related to the amount of high-frequency components in the vicinity of the target position, a third step of outputting a parameter indicating the resolution of the image by the second image signal, Corresponding to the feature amount detected in the step and the parameter output in the third step, a fourth step of generating pixel data of the target position in the second image signal is provided.
[0010]
The image display device according to the present invention includes an image signal input means for inputting a first image signal made up of a plurality of pixel data, and a first image signal inputted from the image signal input means as a plurality of pixel data. An image signal processing means for converting to a second image signal and outputting the image signal; an image display means for displaying an image based on the second image signal output from the image signal processing means on the image display element; Resolution parameter output means for outputting a parameter indicating the resolution of the image based on the image signal. The image signal processing means includes first data selection means for selecting a plurality of first pixel data located around the position of interest in the second image signal based on the first image signal, and the first data selection means. Based on the plurality of first pixel data selected by the data selection means, the feature quantity detection means for detecting the feature quantity related to the high-frequency component quantity around the position of interest, and the feature quantity detection means Pixel data generating means for generating pixel data at the position of interest in the second image signal corresponding to the feature amount and the parameter output from the resolution parameter output means.
[0011]
The program according to the present invention is for causing a computer to execute the above-described image signal processing method. A computer-readable medium according to the present invention records the above-described program.
[0012]
In the present invention, a plurality of first pixel data located around a target position in the second image signal is extracted based on the first image signal, and the target pixel is extracted based on the plurality of first pixel data. A feature quantity related to the high-frequency component quantity around the position is detected. This feature amount is obtained, for example, using the sum of absolute values of adjacent pixels in the plurality of first pixel data and the dynamic range in the plurality of first pixel data.
[0013]
Also, a parameter indicating the resolution of the image by the second information signal is output from the resolution parameter output means. The resolution parameter output means generates a parameter indicating the resolution by, for example, a key input operation or a knob rotation operation.
[0014]
Then, pixel data of the target position in the second image signal is generated corresponding to the above-described feature amount and parameter. For example, pixel data is generated as follows.
[0015]
That is, coefficient data candidates of the estimation formula are generated for a plurality of representative resolutions corresponding to the parameters. For example, when the value of the parameter is between the discrete first value and the second value, the coefficients of the two estimation equations for obtaining the resolution corresponding to the first value and the second value Data is generated as candidate coefficient data.
[0016]
Then, one resolution among a plurality of representative resolutions is specified based on the feature amount and the parameter. For example, resolution selection information in a plurality of feature amount regions corresponding to respective values of the parameters is stored in the storage means, and the resolution is specified using the information. For example, when the resolution corresponding to the second value described above is higher than the resolution corresponding to the first value, the smaller the feature amount, the higher the probability that the second resolution will be specified even if the parameter value is small. .
[0017]
Then, coefficient data corresponding to the specified resolution is selected from the coefficient data candidates. Based on the estimation formula using the coefficient data selected in this way and a plurality of second pixel data located around the target position in the second image signal selected based on the first image signal Thus, pixel data of the target position in the second image signal is calculated.
[0018]
As described above, when the first information signal is converted into the second information signal, the pixel data of the target position in the second image signal is calculated using the coefficient data corresponding to the parameter value indicating the resolution of the image. The user can arbitrarily adjust the resolution of the image to a desired value by changing the parameter value. Further, one coefficient data is selected and used from a plurality of coefficient data candidates corresponding to the parameter value based on the feature amount related to the high-frequency component amount around the position of interest in the second image signal. It is possible to prevent a portion having an inappropriate resolution from occurring in the image based on the image signal 2.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a television receiver 100 as an embodiment. The television receiver 100 obtains an SD signal called a 525i signal from a broadcast signal, converts the 525i signal into an HD signal called a 1050i signal, and displays an image based on the 1050i signal.
[0020]
The television receiver 100 includes a microcomputer, and includes a system controller 101 for controlling the operation of the entire system, and a remote control signal receiving circuit 102 that receives a remote control signal. The remote control signal receiving circuit 102 is connected to the system controller 101, receives a remote control signal RM output from the remote control transmitter 200 according to a user operation, and supplies an operation signal corresponding to the signal RM to the system controller 101. Is configured to do.
[0021]
Further, the television receiver 100 is supplied with a receiving antenna 105 and a broadcast signal (RF modulation signal) captured by the receiving antenna 105, and performs a channel selection process, an intermediate frequency amplification process, a detection process, and the like to generate an SD signal ( The tuner 106 for obtaining the 525i signal) and the buffer memory 109 for temporarily storing the SD signal output from the tuner 106 are provided.
[0022]
Further, the television receiver 100 converts the SD signal (525i signal) temporarily stored in the buffer memory 109 into an HD signal (1050i signal), and an output from the image signal processing unit 110. A display unit 111 for displaying an image based on the HD signal, an OSD (On Screen Display) circuit 112 for generating a display signal SCH for displaying characters, figures, etc. on the screen of the display unit 111; It has a synthesizer 113 for synthesizing the display signal SCH with the HD signal output from the image signal processing unit 110 and supplying it to the display unit 111. The display unit 111 is configured by a flat panel display such as a CRT (cathode-ray tube) display or an LCD (liquid crystal display).
[0023]
The operation of the television receiver 100 shown in FIG. 1 will be described.
The SD signal (525i signal) output from the tuner 106 is supplied to the buffer memory 109 and temporarily stored. The SD signal temporarily stored in the buffer memory 109 is supplied to the image signal processing unit 110 and converted into an HD signal (1050i signal). That is, the image signal processing unit 110 obtains pixel data (hereinafter referred to as “HD pixel data”) that constitutes an HD signal from pixel data (hereinafter referred to as “SD pixel data”) that constitutes an SD signal. The HD signal output from the image signal processing unit 110 is supplied to the display unit 111, and an image based on the HD signal is displayed on the screen of the display unit 111.
[0024]
In addition, the user can adjust the resolution of the image displayed on the screen of the display unit 111 by operating the remote control transmitter 200. For example, in the resolution selection mode, the value of the parameter Q indicating the resolution supplied from the system controller 101 to the image signal processing unit 110 by pressing the up key and the down key or rotating the knob such as a jog dial. Can be changed.
[0025]
As will be described later, in the image signal processing unit 110, the HD pixel data is calculated by an estimation formula. As the coefficient data of the estimation formula, data corresponding to the value of the parameter Q described above is used. Thereby, the resolution of the image by the HD signal output from the image signal processing unit 110 corresponds to the value of the parameter Q.
[0026]
In the state where the value of the parameter Q is changed by the user's operation of the remote control transmitter 200, the value of the parameter Q is displayed on the screen of the display unit 111. Although not shown here, this display is performed using numerical values or bar graphs. The user can change the value of the parameter Q with reference to this display.
[0027]
Thus, when displaying the value of the parameter Q on the screen, the system controller 101 supplies display data to the OSD circuit 112. The OSD circuit 112 generates a display signal SCH based on the display data, and supplies the display signal SCH to the display unit 111 via the synthesizer 113.
[0028]
Next, details of the image signal processing unit 110 will be described. The image signal processing unit 110 selectively extracts data of a plurality of SD pixels located around the target pixel related to the HD signal (1050i signal) from the SD signal (525i signal) stored in the buffer memory 109. Output first to third tap selection circuits 121 to 123.
[0029]
The first tap selection circuit 121 selectively extracts data of SD pixels (referred to as “prediction taps”) used for prediction. The second tap selection circuit 122 selectively extracts data of SD pixels (referred to as “space class taps”) used for class classification corresponding to the level distribution pattern of the SD pixel data. The third tap selection circuit 123 selectively extracts data of SD pixels (referred to as “motion class taps”) used for class classification corresponding to motion. When the space class is determined using SD pixel data belonging to a plurality of fields, motion information is also included in this space class.
[0030]
Further, the image signal processing unit 110 detects the level distribution pattern of the space class tap data (SD pixel data) selectively extracted by the second tap selection circuit 122, and determines the space class based on the level distribution pattern. It has a spatial class detection circuit 124 that detects and outputs the class information.
[0031]
In the space class detection circuit 124, for example, an operation is performed to compress each SD pixel data from 8-bit data to 2-bit data. The space class detection circuit 124 outputs compressed data corresponding to each SD pixel data as class information of the space class. In the present embodiment, data compression is performed by ADRC (Adaptive Dynamic Range Coding). As the information compression means, DPCM (predictive coding), VQ (vector quantization), or the like may be used in addition to ADRC.
[0032]
Originally, ADRC is an adaptive requantization method developed for high performance coding for VTR (Video Tape Recorder), but it can efficiently express local patterns of signal level with short word length. It is suitable for use in data compression. When ADRC is used, the maximum value of space class tap data (SD pixel data) is MAX, the minimum value is MIN, the dynamic range of space class tap data is DR (= MAX−MIN + 1), and the number of requantization bits Is P, the re-quantized code qi as the compressed data is obtained as the class information of the space class for each SD pixel data ki as the space class tap data by the calculation of the equation (1). However, in the expression (1), [] means a truncation process. When there are Na SD pixel data as the space class tap data, i = 1 to Na.
qi = [(ki-MIN + 0.5). 2 ^P / DR] (1)
[0033]
The image signal processing unit 110 detects a motion class mainly representing the degree of motion from the motion class tap data (SD pixel data) selectively extracted by the third tap selection circuit 123, and A motion class detection circuit 125 that outputs class information is provided.
[0034]
In the motion class detection circuit 125, the inter-frame difference is calculated from the motion class tap data (SD pixel data) mi, ni selectively extracted by the third tap selection circuit 123, and the average of absolute values of the differences is calculated. Threshold processing is performed on the value to detect a motion class that is an index of motion. That is, in the motion class detection circuit 125, the average value AV of the absolute value of the difference is calculated by the equation (2). When the third tap selection circuit 123 extracts, for example, six SD pixel data m1 to m6 and six SD pixel data n1 to n6 one frame before as class tap data, equation (2) Nb in is 6.
[0035]
[Expression 1]

[0036]
Then, in the motion class detection circuit 125, the average value AV calculated as described above is compared with one or a plurality of threshold values to obtain class information MV of the motion class. For example, three thresholds th1, th2, th3 (th1 <th2 <th3) are prepared, and when four motion classes are detected, when AV ≦ th1, MV = 0 and th1 <AV ≦ th2 Is MV = 2 when MV = 1, th2 <AV ≦ th3, and MV = 3 when th3 <AV.
[0037]
Also, the image signal processing unit 110 is based on the requantization code qi as the class information of the space class output from the space class detection circuit 124 and the class information MV of the motion class output from the motion class detection circuit 125. A class synthesis circuit 126 is provided for obtaining a class code CL indicating a class to which pixel data (pixel data of the target position) of the HD signal (1050i signal) to be created belongs.
[0038]
In the class synthesis circuit 126, the calculation of the class code CL is performed by the equation (3). In equation (3), Na represents the number of space class tap data (SD pixel data), and P represents the number of requantization bits in ADRC.
[0039]
[Expression 2]

[0040]
The image signal processing unit 110 has a coefficient memory 131. The coefficient memory 131 stores coefficient data of an estimation formula used in an estimated prediction calculation circuit 127 described later. The coefficient data is information used when an SD signal (525i signal) is converted into an HD signal (1050i signal). The coefficient memory 131 is supplied with a class code CL output from the class synthesis circuit 126 and a coefficient selection signal SEL output from a coefficient selection circuit 133 described later as read address information. Coefficient data wi corresponding to the class code CL and the coefficient selection signal SEL is read from the coefficient memory 131 and supplied to the estimated prediction calculation circuit 127.
[0041]
The image signal processing unit 110 includes an information memory bank 132. In the present embodiment, the parameter Q can be changed between 0 and 8. In the information memory bank 132, coefficient data of each class at nine resolutions corresponding to the discrete values 0, 1,..., 8 of the parameter Q are stored in advance. Here, it is assumed that the resolution increases as the value of the parameter Q increases. A method of generating coefficient data corresponding to these nine resolutions will be described later.
[0042]
As described above, when the 525i signal is converted into the 1050i signal, it is necessary to obtain four pixels of the 1050i signal corresponding to one pixel of the 525i signal in each of the odd and even fields. Therefore, a certain class of coefficient data at a certain resolution is composed of coefficient data corresponding to four pixels in a 2 × 2 unit pixel block constituting a 1050i signal in each of odd and even fields. The four pixels in the 2 × 2 unit pixel block have different phase relationships corresponding to the pixels of the 525i signal. A method of generating coefficient data corresponding to the plurality of resolutions will be described later.
[0043]
As described above, the user supplies the image signal processing unit 110 from the system controller 101 by pressing the up key and the down key or rotating a knob such as a jog dial on the operation unit of the remote control transmitter 200. The value of the parameter Q to be changed can be changed. The parameter Q is supplied to the information memory bank 132, and two discrete values m, m + 1 (m = 0, 1,...) Located in the vicinity of the value of the parameter Q are supplied from the information memory bank 132 to the coefficient memory 131. .. Coefficient data corresponding to 7) is loaded.
[0044]
That is, when 0 ≦ Q ≦ 1, the coefficient data corresponding to Q = 0, 1 is 1 <Q ≦ 2, and when 1 <Q ≦ 2, the coefficient data corresponding to Q = 1, 2 is 2 <Q ≦ 3. When the coefficient data corresponding to Q = 2, 3 is 3 <Q ≦ 4, the coefficient data corresponding to Q = 3, 4 is Q = 4,5 when 4 <Q ≦ 5. When the coefficient data corresponding to 5 <Q ≦ 6, the coefficient data corresponding to Q = 5, 6 is satisfied, and when 6 <Q ≦ 7, the coefficient data corresponding to Q = 6, 7 is 7 When <Q ≦ 8, coefficient data corresponding to Q = 7, 8 is loaded from the information memory bank 132 to the coefficient memory 131.
[0045]
In addition, the image signal processing unit 110 includes a coefficient selection circuit 133 that generates a coefficient selection signal SEL. The coefficient selection signal SEL is supplied to the coefficient memory 131 as read address information as described above, and is loaded into two discrete values of the parameter Q stored in the coefficient memory 131 after being loaded from the information memory bank 132. This is used to select one coefficient data among the corresponding coefficient data.
[0046]
FIG. 2 shows the configuration of the coefficient selection circuit 133. The coefficient selection circuit 133 includes a feature amount detection unit 141, a feature amount memory 142, a feature amount region determination unit 143, a region detection unit 144, and a coefficient selection signal generation unit 145.
[0047]
The feature amount detection unit 141 detects the feature amount CH for each SD pixel constituting the SD signal (525i signal) of each field temporarily stored in the buffer memory 109. In the present embodiment, the feature amount CH corresponding to a certain SD pixel (target pixel) is a value obtained by taking the square root of the product of the dynamic range DR and activity ACT in a block of a predetermined size centered on the SD pixel ( √ (DR × ACT) The block size is, for example, 5 × 5.
[0048]
As shown in FIG. 3, the dynamic range DR is data of 25 SD pixels included in a 5 × 5 block centered on the pixel of interest. _{i-2, j + 2} ~ X _{i + 2, j-2} In this case, when the maximum value is MAX and the minimum value is MIN, it is defined by equation (4). In FIG. 3, the coordinates of the pixel of interest are (i, j).
DR = MAX-MIN (4)
[0049]
In the activity ACT, as shown in FIG. 4, the coordinate of the pixel of interest is (i, j), and the data of 25 SD pixels included in a 5 × 5 block centered on the pixel of interest is x _{i-2, j + 2} ~ X _{i + 2, j-2} Is defined by equation (5). Where i ₁ = I-2, ..., i + 1, i ₂ = I-2, ..., i + 2, j ₁ = J-2,..., J + 2, j ₂ = J-2, ..., j + 1.
[0050]
[Equation 3]

[0051]
FIG. 5 shows a model of the detection part by the dynamic range DR and activity ACT. When the dynamic range DR is used, the outline of the image is detected as indicated by the bold line at the upper right in FIG. On the other hand, when the activity ACT is used, a high frequency region surrounded by a low frequency region of an image is detected as indicated by a thick line at the lower right in FIG. Since the feature amount CH is defined by √ (DR × ACT) as described above, when this feature amount CH is used, both the contour of the image and the high frequency region surrounded by the low frequency region of the image are detected. It will be.
[0052]
As described above, when a 525i signal is converted into a 1050i signal, in each of the odd and even fields, four pixels of the 1050i signal are obtained by an estimation equation corresponding to one pixel of the 525i signal. is there. Therefore, the feature amount detection unit 141 detects the feature amount CH corresponding to each pixel constituting the SD signal (525i signal) means that each of the four pixels (target pixel) constituting the HD signal (1050i signal). That is, the feature amount CH related to the high-frequency component amount in the vicinity of is detected.
[0053]
The feature amount detection unit 141 performs a feature amount CH detection process on an SD signal in a field stored in the buffer memory 109, for example, in a vertical blanking period. The feature amount memory 142 stores a feature amount CH corresponding to each SD pixel for one field detected in a certain vertical blanking period in the feature amount detection unit 141.
[0054]
In addition, the feature amount region determination unit 143 uses the feature amount CH corresponding to all SD pixels in a certain field stored in the feature amount memory 142 to set a range from the minimum value to the maximum value of the feature amount CH in four regions. The four feature amount regions are determined by dividing the image into four. The feature amount region determination unit 143 performs the feature amount region determination process in the vertical blanking period. In this case, four feature amount regions are determined so that the number of feature amount regions included in each feature amount region among feature amounts CH corresponding to all SD pixels is substantially equal.
[0055]
FIG. 6 shows a histogram model of the feature amount CH corresponding to all SD pixels. CHmin indicates the minimum value of the feature amount CH, and CHmax indicates the maximum value of the feature amount CH. Ra, Rb, Rc, and Rd are four feature amount regions, and Na, Nb, Nc, and Nd indicate the number included in each feature amount region among the feature amounts CH corresponding to all SD pixels. In this case, the feature amount regions Ra, Rb, Rc, and Rd are determined so that the numbers Na, Nb, Nc, and Nd are substantially equal.
[0056]
Here, the significance of the feature amount regions Ra, Rb, Rc, and Rd will be considered. Since the feature amount CH is large in the order of Ra, Rb, Rc, and Rd and the high frequency component amount is large, when generating HD pixel data from SD pixel data using coefficient data for obtaining the same resolution in the entire screen, A portion where the feature amount CH in the feature amount region on the Rd side is detected tends to have an inappropriate resolution. In FIG. 7, a, b, c, and d indicate locations on the screen where the feature amounts CH in the feature amount areas of Ra, Rb, Rc, and Rd are detected, respectively. If the degree of inappropriate resolution (failure degree) at each of these locations is pa, pb, pc, pd, the relationship is pa <pb <pc <pd.
[0057]
The region detection unit 144 sequentially extracts the feature amount CH corresponding to each SD pixel detected in the vertical blanking period in the feature amount detection unit 141 and stored in the feature amount memory 142 in the subsequent vertical effective scanning period. A feature amount CH corresponding to an SD pixel is detected as to which of the feature amount regions Ra, Rb, Rc, and Rd determined by the above-described feature amount region determining unit 143, and detection information DET is output. It is.
[0058]
The coefficient selection signal generation unit 145 generates a coefficient selection signal SEL from the detection information DET from the area detection unit 144 and the value of the parameter Q supplied from the system controller 101.
[0059]
The coefficient selection signal generation unit 145 includes a ROM (read only memory) 146 serving as a storage unit that stores the resolution selection information RES corresponding to each value of the parameter Q in the above-described feature amount regions Ra, Rb, Rc, and Rd. have.
[0060]
FIG. 8 schematically shows the resolution selection information RES stored in the ROM 146.
In this figure, in the range (first range) in which “a” is described, RES = 1 when the feature amount CH is included in the feature amount region Ra, and the feature amount CH is the feature amount region Rb, Rc, Rd. Means that RES = 0, and in the range in which “a, b” is described (second range), RES = 1 when the feature amount CH is included in the feature amount regions Ra, Rb. Yes, this means that RES = 0 when the feature amount CH is included in the feature amount regions Rc and Rd, and in the range where “a, b, c” is described (third range), the feature amount CH is RES = 1 when included in the feature amount region Ra, Rb, Rc, and RES = 0 when the feature amount CH is included in the feature amount region Rd, and “a, b, c, d” In the described range (fourth range), the feature amount CH is the feature amount region Ra, Rb, Rc. Even when included in any of Rd means that a RES = 1.
[0061]
In this figure, i <Q ≦ (i + 0.25) corresponds to the first range, (i + 0.25) <Q ≦ (i + 0.5) corresponds to the second range, and (i + 0.5). ) <Q ≦ (i + 0.75) corresponds to the third range, and (i + 0.75) <Q ≦ (i + 1) corresponds to the fourth range. Here, i = 0, 1,... When Q = 0, RES = 0 even when the feature amount CH is included in any of the feature amount regions Ra, Rb, Rc, Rd.
[0062]
The coefficient selection signal generation unit 145 retrieves the detection information DET from the region detection unit 144 and the resolution selection information RES corresponding to the value of the parameter Q supplied from the system controller 101 from the ROM 146, and selects the resolution selection information RES as a coefficient. Output as signal SEL. For example, when the value of the parameter Q is 0.4 and the detection information DET indicates that the feature amount CH is included in the feature amount region Ra, SEL = 1 is extracted from the ROM 146 and is used as the coefficient selection signal SEL. 1 is output.
[0063]
The coefficient selection signal SEL output from the coefficient selection signal generation unit 145 also serves as the output of the coefficient selection circuit 133. As described above, the coefficient selection signal SEL output from the coefficient selection circuit 133 is supplied to the coefficient memory 131 as read address information as described above. The coefficient memory 131 (see FIG. 1) corresponds to two discrete values m, m + 1 (m = 0, 1,..., 7) located near the value of the parameter Q from the information memory bank 132 as described above. The coefficient data corresponding to the discrete value m is read when SEL = 0, and the coefficient data corresponding to the discrete value m + 1 is read when SEL = 1.
[0064]
Returning to FIG. 1, the image signal processing unit 110 also includes prediction tap data (SD pixel data) xi selectively extracted by the first tap selection circuit 121 and coefficient data wi read from the coefficient memory 131. Therefore, an estimated prediction calculation circuit 127 that calculates pixel data (pixel data of the target position) y of the HD signal to be generated is included.
[0065]
As described above, when the SD signal (525i signal) is converted to the HD signal (1050i signal), it is necessary to obtain four pixels of the HD signal for one pixel of the SD signal. In the circuit 127, HD pixel data is generated for each 2 × 2 unit pixel block constituting the HD signal.
[0066]
That is, the estimated prediction calculation circuit 127 includes the prediction tap data xi corresponding to the data of the four pixels in the unit pixel block (pixel data at the target position) from the first tap selection circuit 121, and the coefficient memory 131. The coefficient data wi corresponding to the four pixels constituting the unit pixel block is supplied, and the data y of the four pixels constituting the unit pixel block ₁ ~ Y _Four Are individually calculated by the estimation equation (6).
[0067]
[Expression 4]

[0068]
In addition, the image signal processing unit 110 outputs the data y of four pixels constituting the unit pixel block that is sequentially output from the estimated prediction calculation circuit 127. ₁ ~ Y _Four Are processed in a line sequential manner and output in a 1050i signal format.
[0069]
Next, the operation of the image signal processing unit 110 will be described.
From the SD signal (525i signal) stored in the buffer memory 109, the second tap selection circuit 122 uses the four pixels in the unit pixel block constituting the HD signal (1050i signal) to be created (the pixel at the target position). The data of space class taps (SD pixel data) located in the vicinity of is selectively extracted. The space class tap data (SD pixel data) selectively extracted by the second tap selection circuit 122 is supplied to the space class detection circuit 124. In this space class detection circuit 124, each of the SD pixel data as space class tap data is subjected to ADRC processing and re-used as class information of the space class (mainly class classification for waveform expression in space). A quantization code qi is obtained (see equation (1)).
[0070]
In addition, from the SD signal (525i signal) stored in the buffer memory 109, the third tap selection circuit 123 uses the four pixels in the unit pixel block constituting the HD signal (1050i signal) to be created (at the target position). The motion class tap data (SD pixel data) located around the (pixel) is selectively extracted. The motion class tap data (SD pixel data) selectively extracted by the third tap selection circuit 123 is supplied to the motion class detection circuit 125. In this motion class detection circuit 125, class information MV of a motion class (mainly class classification for representing the degree of motion) is obtained from each SD pixel data as motion class tap data.
[0071]
The class information MV and the above-described requantization code qi are supplied to the class synthesis circuit 126. In this class synthesis circuit 126, for each unit pixel block constituting the HD signal (1050i signal) to be created from the class information MV and the requantization code qi, data of four pixels in the unit pixel block (attention) A class code CL indicating the class to which the pixel data at the position belongs is obtained (see equation (3)). The class code CL is supplied to the coefficient memory 131 as read address information.
[0072]
Further, from the SD signal (525i signal) stored in the buffer memory 109, the coefficient selection circuit 133 uses four pixels (in the unit pixel block) for each unit pixel block constituting the HD signal (1050i signal) to be created. A coefficient selection signal SEL corresponding to the pixel at the target position is generated.
[0073]
That is, as shown in FIG. 2, the SD signal (525i signal) stored in the buffer memory 109 is supplied to the feature amount detection unit 141 of the coefficient selection circuit 133, and the feature amount detection unit 141 converts the SD signal of each field. A feature amount CH = √ (DR × ACT) is detected for each SD pixel constituting the same. The feature quantity CH corresponding to the SD signal for one field detected in the vertical blanking period by the feature quantity detection unit 141 is stored in the feature quantity memory 142.
[0074]
As described above, when a 525i signal is converted into a 1050i signal, in each of the odd and even fields, four pixels of the 1050i signal are obtained by an estimation equation corresponding to one pixel of the 525i signal. is there. Therefore, the feature amount detection unit 141 detects the feature amount CH corresponding to each pixel constituting the SD signal (525i signal) means that each of the four pixels (target pixel) constituting the HD signal (1050i signal). Therefore, the feature amount CH corresponding to is detected.
[0075]
Further, the feature amount region determination unit 143 uses the feature amount CH corresponding to the SD signal for one field stored in the feature amount memory 142 in a certain vertical blanking period, and the feature amount CH corresponding to all SD pixels. A range from the minimum value CHmin to the maximum value CHmax is divided into four regions, and four feature amount regions Ra, Rb, Rc, and Rd are determined (see FIG. 6). In this case, the ranges of the four feature amount regions Ra, Rb, Rc, and Rd are determined so that the number included in each feature amount region among the feature amounts CH corresponding to all SD pixels is substantially equal.
[0076]
Then, the SD signal for one field stored in the feature amount memory 142 in a certain vertical blanking period is sequentially extracted in the subsequent vertical effective scanning period and supplied to the region detection unit 144, and the feature amount corresponding to each SD pixel. It is detected which of the above-described feature amount areas Ra, Rb, Rc, and Rd is CH. The detection information DET is supplied to the coefficient selection signal generation unit 145.
[0077]
The coefficient selection signal generator 145 is further supplied with a parameter Q from the system controller 101. As described above, the resolution selection information RES in the feature amount regions Ra, Rb, Rc, and Rd corresponding to each value of the parameter Q is stored in the ROM 146 that the coefficient selection signal generation unit 145 has. In the coefficient selection signal generation unit 145, detection information DET from the region detection unit 144 and resolution selection information RES corresponding to the value of the parameter Q supplied from the system controller 101 are extracted from the ROM 146.
[0078]
The extracted coefficient selection information RES becomes the output of the coefficient selection signal generation unit 145 and thus the coefficient selection circuit 133. Therefore, the coefficient selection circuit 133 outputs a coefficient selection signal SEL corresponding to four pixels (pixels at the target position) in the unit pixel block for each unit pixel block constituting the HD signal (1050i signal) to be created. The Rukoto. The coefficient selection signal SEL is supplied to the coefficient memory 131 as read address information.
[0079]
The coefficient memory 131 stores coefficient data of each class corresponding to two discrete values m, m + 1 (m = 0, 1,..., 7) located in the vicinity of the value of the parameter Q from the information memory bank 132. Has been loaded. Such coefficient data loading operation is performed, for example, when the value of the parameter Q is changed and the coefficient data to be stored in the coefficient memory 131 needs to be changed.
[0080]
As described above, the class code CL and the coefficient selection signal CL are supplied to the coefficient memory 131 as read address information, so that the coefficient data wi corresponding to the class code CL from the coefficient memory 131 and corresponding to the coefficient selection signal SEL. Is read and supplied to the estimated prediction calculation circuit 127. In this case, coefficient data corresponding to the discrete value m is read when SEL = 0, and coefficient data corresponding to the discrete value m + 1 is read when SEL = 1.
[0081]
Further, in the first tap selection circuit 121, four pixels (units of the target position) in the unit pixel block constituting the HD signal (1050i signal) to be created are generated from the SD signal (525i signal) stored in the buffer memory 109. Prediction tap data (SD pixel data) located around the (pixel) is selectively extracted. The prediction tap data (SD pixel data) xi selectively extracted by the first tap selection circuit 121 is supplied to the estimated prediction calculation circuit 127.
[0082]
In the estimated prediction calculation circuit 127, four pixels in a unit pixel block constituting an HD signal to be created from prediction tap data (SD pixel data) xi and coefficient data wi for four pixels read from the coefficient memory 131. Data y ₁ ~ Y _Four Are calculated individually (see equation (6)). Then, 4-pixel data y sequentially output from the estimated prediction calculation circuit 127. ₁ ~ Y _Four Is supplied to the post-processing circuit 128. The post-processing circuit 128 outputs 4-pixel data y sequentially output from the estimated prediction calculation circuit 127. ₁ ~ Y _Four Are line-sequentially output in a 1050i signal format. That is, the post-processing circuit 128 outputs a 1050i signal as an HD signal.
[0083]
As described above, each coefficient memory 131 corresponds to two discrete values m, m + 1 (m = 0, 1,..., 7) located in the vicinity of the value of the parameter Q supplied from the system controller 101. Class coefficient data is loaded from the information memory bank 132. Therefore, when the user operates the remote control transmitter 200 to change the value of the parameter Q, the coefficient data stored in the coefficient memory 131 is changed accordingly, and the estimated prediction calculation circuit 127 converts the pixel data of the HD signal into the parameter Q. It is generated corresponding to the value of. Therefore, the user can arbitrarily adjust the resolution of the image by the HD signal to a desired value as in the conventional adjustment of contrast and sharpness by changing the value of the parameter Q.
[0084]
Further, of the coefficient data of each class corresponding to two discrete values m, m + 1 (m = 0, 1,..., 7) located in the vicinity of the value of the parameter Q stored in the coefficient memory 131, the estimation is performed. Coefficient data used when the prediction calculation circuit 127 actually generates the pixel data of the HD signal is determined based on the coefficient selection signal SEL generated by the coefficient selection circuit 133. In other words, in which feature quantity region the degree (destruction level) of the feature quantity CH around the four pixels (the pixel at the target position) in the unit pixel block constituting the HD signal to be created has an inappropriate resolution (destruction level) is included. Depending on whether the value of the parameter Q is from m to m + 1, it is determined whether to use coefficient data corresponding to the discrete value m or coefficient data corresponding to the discrete value m + 1. Incidentally, the coefficient data corresponding to the discrete value m + 1 is for obtaining a higher resolution than the coefficient data corresponding to the discrete value m.
[0085]
For example, the coefficient data corresponding to the discrete value m + 1 is used only when the value of the parameter Q is closer to m and the feature value CH is included in the feature value region where the degree of inappropriate resolution (failure degree) is low. (See FIG. 8). As a result, it is possible to prevent a portion where the feature amount CH is included in the feature amount region having a high degree of inappropriate resolution (destructive degree) from being inappropriate resolution, and to improve the image quality of the HD signal. be able to.
[0086]
FIG. 9 shows a case where each of the locations a to d in the screen is in the same state as described with reference to FIG. 7, and when the value of the parameter Q changes from m to m + 1, the discrete value m or discrete at each location. This indicates which of the value m + 1 corresponds to which coefficient data is used.
[0087]
When Q = m, as shown in FIG. 9A, coefficient data wm corresponding to the discrete value m is used at all points a to d. When m <Q ≦ m + 0.25, as shown in FIG. 9B, coefficient data wm + 1 corresponding to the discrete value m + 1 is used at the location a, and the discrete value at locations b to d. Coefficient data wm corresponding to m is used. When m + 0.25 <Q ≦ m + 0.5, as shown in FIG. 9C, coefficient data wm + 1 corresponding to the discrete value m + 1 is used at points a and b, and c and d The coefficient data wm corresponding to the discrete value m is used at the location. When m + 0.5 <Q ≦ m + 0.75, as shown in FIG. 9D, coefficient data wm + 1 corresponding to the discrete value m + 1 is used at the positions a to c, and at the position d. Coefficient data wm corresponding to the discrete value m is used. Furthermore, when m + 0.75 <Q ≦ m + 1, as shown in FIG. 9E, coefficient data wm + 1 corresponding to the discrete value m + 1 is used at all points a to d.
[0088]
In the above-described embodiment, the feature amount CH related to the high-frequency component amount around the pixel of interest is represented by √ (DR × ACT), but is not limited to this. Absent. The feature amount CH only needs to be capable of classifying the degree of inappropriate resolution (failure degree) in stages when obtaining HD signals using coefficient data for obtaining the same resolution.
[0089]
In the above-described embodiment, for simplicity of explanation, the range from the minimum value CHmin to the maximum value CHmax of the feature amount CH is divided into four regions to determine four feature amount regions Ra to Rd (see FIG. 6), and correspondingly, each of the discrete values of the parameter Q is divided into four ranges (see FIG. 8). However, these numbers are actually increased, for example, 10. The
[0090]
In the above-described embodiment, the number Na, Nb, Nc, Nd included in each feature amount region among the feature amounts CH corresponding to all SD pixels is made substantially equal, but it is not always necessary to make them equal. . However, by making the numbers Na, Nb, Nc, and Nd substantially equal, it is possible to expect a change in the resolution of the HD image in proportion to the change in the value of the parameter Q.
[0091]
Next, a method for generating coefficient data corresponding to nine resolutions corresponding to discrete values 0, 1,..., 8 of the parameter Q stored in the information memory bank 132 will be described. This coefficient data is generated in advance by learning.
[0092]
First, this learning method will be described. An example in which coefficient data wi (i = 1 to n) based on the estimation formula (6) is obtained by the method of least squares will be shown. As a generalized example, consider the observation equation (7), where X is input data, W is coefficient data, and Y is a predicted value. In this equation (7), m represents the number of learning data, and n represents the number of prediction taps.
[0093]
[Equation 5]

[0094]
The least square method is applied to data collected by the observation equation (7). Consider the residual equation (8) based on the observation equation (7).
[0095]
[Formula 6]

[0096]
From the residual equation of equation (8), the most probable value of each w i is e in equation (9). ² It is considered that the condition for minimizing is satisfied. That is, the condition of equation (10) should be considered.
[0097]
[Expression 7]

[0098]
That is, w conditions satisfying n conditions based on i in equation (10) are considered. ₁ , W ₂ , ..., w _n May be calculated. Therefore, Equation (11) is obtained from the residual equation of Equation (8). Furthermore, the equation (12) is obtained from the equations (11) and (7).
[0099]
[Equation 8]

[0100]
And the normal equation of (13) Formula is obtained from (8) Formula and (12) Formula.
[0101]
[Equation 9]

[0102]
Since the number of equations equal to the number n of unknowns can be established as the normal equation of equation (13), the most probable value of each wi can be obtained. In this case, simultaneous equations are solved using a sweeping method (Gauss-Jordan elimination method) or the like.
[0103]
FIG. 10 shows a coefficient data generation device 150 that generates coefficient data based on the concept described above. The coefficient data generation apparatus 150 performs an horizontal thinning process and a vertical thinning process on an input terminal 151 to which an HD signal (1050i signal) as a teacher signal is input, and an SD signal as a student signal. And an SD signal generation circuit 152 to be obtained.
[0104]
The SD signal generation circuit 152 is supplied with a parameter Q as a control signal. This parameter Q corresponds to the parameter Q output from the system controller 101 by the user's operation of the remote control transmitter 200 in the television receiver 100 shown in FIG. However, here, only nine discrete values of 0, 1,.
[0105]
In the SD signal generation circuit 152, the horizontal and vertical bands of the filter used when generating the SD signal from the HD signal are varied according to the value of the parameter Q. This filter includes, for example, a one-dimensional Gaussian filter that limits the horizontal band and a one-dimensional Gaussian filter that limits the vertical band. This one-dimensional Gaussian filter is expressed by equation (14).
[0106]
[Expression 10]

[0107]
In this case, a one-dimensional Gaussian filter having a frequency characteristic corresponding to the discrete value of Q can be obtained by stepwise changing the value of the standard deviation σ corresponding to the discrete value of Q. In this case, the horizontal and vertical bands are narrowed as the value of the parameter Q increases. As a result, the larger the value of the parameter Q, the more the coefficient data for obtaining a high-resolution HD signal can be generated.
[0108]
Further, the coefficient data generation device 150 selectively selects data of a plurality of SD pixels located around the target position in the HD signal (1050i signal) from the SD signal (525i signal) output from the SD signal generation circuit 152. First to third tap selection circuits 153 to 155 for taking out and outputting are provided. These first to third tap selection circuits 153 to 155 are configured similarly to the first to third tap selection circuits 121 to 123 of the image signal processing unit 110 described above.
[0109]
Further, the coefficient data generation device 150 detects a level distribution pattern of space class tap data (SD pixel data) selectively extracted by the second tap selection circuit 154, and determines a space class based on the level distribution pattern. It has a space class detection circuit 157 that detects and outputs the class information. The space class detection circuit 157 is configured in the same manner as the space class detection circuit 124 of the image signal processing unit 110 described above. From this space class detection circuit 157, a requantization code qi for each SD pixel data as space class tap data is output as class information indicating a space class.
[0110]
The coefficient data generation device 150 detects a motion class mainly representing the degree of motion from the motion class tap data (SD pixel data) selectively extracted by the third tap selection circuit 155, and A motion class detection circuit 158 that outputs class information MV is provided. The motion class detection circuit 158 is configured in the same manner as the motion class detection circuit 125 of the image signal processing unit 110 described above. In this motion class detection circuit 158, the inter-frame difference is calculated from the motion class tap data (SD pixel data) selectively extracted by the third tap selection circuit 155, and the difference between the absolute values of the absolute values of the difference is calculated. Then, threshold processing is performed to detect a motion class that is an index of motion.
[0111]
Also, the coefficient data generation device 150 is based on the requantization code qi as the class information of the space class output from the space class detection circuit 157 and the motion class class information MV output from the motion class detection circuit 158. A class synthesis circuit 159 for obtaining a class code CL indicating a class to which pixel data of the target position in the HD signal (1050i signal) belongs is provided. The class synthesis circuit 159 is also configured similarly to the class synthesis circuit 126 of the image signal processing unit 110 described above.
[0112]
Further, the coefficient data generation device 150 includes each HD pixel data y as pixel data of the target position obtained from the HD signal supplied to the input terminal 151, and a first tap corresponding to each HD pixel data y. From the prediction tap data (SD pixel data) xi selectively extracted by the selection circuit 153 and the class code CL output from the class synthesis circuit 159 corresponding to each HD pixel data y, n A normal equation generation unit 160 that generates a normal equation (see equation (13)) for obtaining the coefficient data wi is provided.
[0113]
In this case, the above-described learning data is generated by a combination of one HD pixel data y and n prediction tap pixel data corresponding to the HD pixel data y. Accordingly, the normal equation generating unit 160 has a normal equation in which a lot of learning data is registered. Is generated. Although not shown in the figure, SD pixel data supplied from the first tap selection circuit 153 to the normal equation generation unit 160 by arranging a delay circuit for time adjustment in the preceding stage of the first tap selection circuit 153. Timing adjustment of xi is performed.
[0114]
The coefficient data generation device 150 is supplied with the data of the normal equation generated for each class by the normal equation generation unit 160, solves the normal equation generated for each class, and obtains coefficient data wi for each class. A data determination unit 161 and a coefficient memory 162 that stores the obtained coefficient data wi are provided. In the coefficient data determination unit 161, the normal equation is solved by, for example, a sweeping method, and the coefficient data wi is obtained.
[0115]
The operation of the coefficient data generation device 150 shown in FIG. 10 will be described. An HD signal (1050i signal) as a teacher signal is supplied to the input terminal 151, and the HD signal is subjected to horizontal and vertical thinning processing by the SD signal generation circuit 152, and an SD signal (525i) as a student signal. Signal) is generated. In this case, the SD signal generation circuit 152 is supplied with the parameter Q as a control signal, and sequentially generates a plurality of SD signals whose horizontal and vertical bands are changed stepwise corresponding to the discrete values of the parameter Q. It will be done.
[0116]
From this SD signal (525i signal), the second tap selection circuit 154 selectively extracts data (SD pixel data) of the space class tap located around the position of interest in the HD signal (1050i signal). The space class tap data (SD pixel data) selectively extracted by the second tap selection circuit 154 is supplied to the space class detection circuit 157. In this space class detection circuit 157, each SD pixel data as space class tap data is subjected to ADRC processing to be re-used as class information of a space class (mainly class classification for waveform expression in space). A quantization code qi is obtained (see equation (1)).
[0117]
Further, from the SD signal generated by the SD signal generation circuit 152, the third tap selection circuit 155 selectively extracts data of the motion class tap (SD pixel data) located around the target position in the HD signal. . The motion class tap data (SD pixel data) selectively extracted by the third tap selection circuit 155 is supplied to the motion class detection circuit 158. In this motion class detection circuit 158, class information MV of a motion class (mainly class classification for representing the degree of motion) is obtained from each SD pixel data as motion class tap data.
[0118]
The class information MV and the above-described requantization code qi are supplied to the class synthesis circuit 159. The class synthesis circuit 159 obtains a class code CL indicating the class to which the pixel data at the position of interest in the HD signal (1050i signal) belongs from the class information MV and the requantization code qi (see equation (3)). .
[0119]
Further, from the SD signal generated by the SD signal generation circuit 152, the first tap selection circuit 153 selectively extracts data of prediction taps (SD pixel data) located around the target pixel related to the HD signal. . Then, each HD pixel data y as pixel data of the target position obtained from the HD signal supplied to the input terminal 151 and the first tap selection circuit 121 corresponding to each HD pixel data y are selectively selected. From the prediction tap data (SD pixel data) xi taken out and the class code CL output from the class synthesis circuit 159 corresponding to each HD pixel data y, the normal equation generation unit 160 sets n for each class. A normal equation for generating the coefficient data wi is generated.
[0120]
Then, the coefficient data determination unit 161 solves the normal equation to obtain the coefficient data wi of each class, and the coefficient data wi is stored in the coefficient memory 162 that is divided into addresses for each class.
[0121]
As described above, the coefficient data generation device 150 shown in FIG. 10 can generate the coefficient data wi of each class stored in the information memory bank 132 of the image signal processing unit 110 of FIG. In this case, the horizontal and vertical bands of the SD signal generated by the SD signal generation circuit 152 can be changed stepwise according to the value of the parameter Q. Therefore, by sequentially changing the value of the parameter Q to 0, 1,..., 8 and determining the coefficient data wi for each class, the discrete values of the parameters Q of 0, 1,. It is possible to generate coefficient data wi for each class corresponding to various values.
[0122]
Note that the processing in the image signal processing unit 110 in FIG. 1 can be realized by software, for example, by an image signal processing apparatus 300 as shown in FIG.
[0123]
First, the image signal processing apparatus 300 shown in FIG. 11 will be described. The image signal processing apparatus 300 includes a CPU 301 that controls the operation of the entire apparatus, a ROM (read only memory) 302 that stores an operation program of the CPU 301, coefficient data, and the like, and a RAM (random) that forms a work area of the CPU 301. access memory) 303. These CPU 301, ROM 302, and RAM 303 are each connected to a bus 304.
[0124]
The image signal processing apparatus 300 also includes a hard disk drive (HDD) 305 as an external storage device and a floppy (R) disk drive (FDD) 307 that drives a floppy (R) disk 306. These drives 305 and 307 are each connected to a bus 304.
[0125]
In addition, the image signal processing apparatus 300 includes a communication unit 308 that is connected to a communication network 400 such as the Internet by wire or wirelessly. The communication unit 308 is connected to the bus 304 via the interface 309.
[0126]
In addition, the image signal processing device 300 includes a user interface unit. The user interface unit includes a remote control signal receiving circuit 310 that receives a remote control signal RM from the remote control transmitter 200, and a display 311 that includes an LCD (liquid crystal display) or the like. The receiving circuit 310 is connected to the bus 304 via the interface 312, and similarly the display 311 is connected to the bus 304 via the interface 313.
[0127]
Further, the image signal processing apparatus 300 includes an input terminal 314 for inputting an SD signal and an output terminal 315 for outputting an HD signal. The input terminal 314 is connected to the bus 304 via the interface 316, and similarly, the output terminal 315 is connected to the bus 304 via the interface 317.
[0128]
Here, instead of storing the processing program, coefficient data, and the like in advance in the ROM 302 as described above, for example, they are downloaded from the communication network 400 such as the Internet via the communication unit 308 and stored in the hard disk or RAM 303 for use. You can also. Further, these processing programs, coefficient data, and the like may be provided on the floppy (R) disk 306.
[0129]
Further, instead of inputting the SD signal to be processed from the input terminal 314, it may be recorded in advance on a hard disk or downloaded from the communication network 400 such as the Internet via the communication unit 308. Also, instead of outputting the processed HD signal to the output terminal 315 or in parallel therewith, it is supplied to the display 311 to display an image, further stored in a hard disk, or via the communication unit 308 such as the Internet. It may be sent to the communication network 400.
[0130]
A processing procedure for obtaining an HD signal from an SD signal in the image signal processing apparatus 300 shown in FIG. 11 will be described with reference to the flowchart of FIG.
First, in step ST1, processing is started, and in step ST2, SD pixel data is input in field units. When the SD pixel data is input from the input terminal 314, the SD pixel data is temporarily stored in the RAM 303. When this SD pixel data is recorded on the hard disk, this SD pixel data is read by the hard disk drive 307 and temporarily stored in the RAM 303. In step ST3, it is determined whether or not the processing of all fields of the input SD pixel data has been completed. When the process is finished, the process ends in step ST4. On the other hand, when the process is not finished, the process proceeds to step ST5.
[0131]
In step ST5, the value of the parameter Q input by the user operating the remote control transmitter 200 is read from the RAM 303, for example. In step ST6, coefficient data of each class corresponding to two discrete values m, m + 1 (m = 0, 1,..., 7) located in the vicinity of the read parameter Q value is read out and stored in the RAM 303. Store temporarily.
[0132]
Next, in step ST7, the feature amount CH (√ (DR × ACT)) of each SD pixel is obtained from the SD pixel data for one field input in step ST2, and the feature amount CH of each SD pixel is used. Thus, four feature amount regions Ra to Rd are determined (see FIG. 6). Note that the feature amount CH of each SD pixel is stored in the RAM 303 for further use in a later step.
[0133]
Next, in step ST8, the pixel data of the class tap and the prediction tap are acquired from the SD pixel data input in step ST2 corresponding to each HD pixel data (target pixel data) to be generated. In step ST9, it is determined whether or not the processing for obtaining HD pixel data has been completed in all areas of the input SD pixel data. If the process has not ended, the process proceeds to step ST10.
[0134]
In this step ST10, it is detected which of the above-described four feature amount regions Ra to Rd the feature amount CH of the SD pixel corresponding to each HD pixel data to be generated (pixel data of the target position) is detected. In step ST11, a coefficient selection signal SEL is generated from the detection information DET and the value of the parameter Q to determine which coefficient data corresponding to the discrete value m or m + 1 is to be used.
[0135]
Next, in step ST12, a class code CL is generated from the SD pixel data of the class tap acquired in step ST8. In step 13, coefficient data corresponding to the discrete value indicated by the coefficient selection signal SEL generated in step ST11, the coefficient data of the class indicated by the class code CL generated in step ST12, and a prediction tap SD pixel data is used to generate HD pixel data corresponding to the value of the parameter Q using the estimation formula (see formula (6)), and then the process returns to step ST8 to repeat the same processing as described above. .
[0136]
If the process is completed in step ST9, the process returns to step ST2 and proceeds to the input process of SD pixel data in the next field.
[0137]
In this way, by performing processing according to the flowchart shown in FIG. 12, it is possible to process the SD pixel data constituting the input SD signal and obtain HD pixel data constituting the HD signal. As described above, the HD signal obtained by such processing is output to the output terminal 315, supplied to the display 311 to display an image, and further supplied to the hard disk drive 305 to be supplied to the hard disk. It is recorded.
[0138]
In the above-described embodiment, the linear equation is used as the estimation equation when generating the HD signal. However, the present invention is not limited to this, and for example, a higher-order equation is used as the estimation equation. It may be a thing.
[0139]
In the above-described embodiment, an example in which an SD signal (525i signal) is converted into an HD signal (1050i signal) has been described. However, the present invention is not limited to this, and the first equation is estimated using an estimation formula. Of course, the present invention can be similarly applied to other cases in which the image signal is converted into the second image signal.
[0140]
【The invention's effect】
According to the present invention, when converting the first information signal into the second information signal, the pixel data of the target position in the second image signal using the coefficient data corresponding to the parameter value indicating the resolution of the image. The user can arbitrarily adjust the resolution of the image to a desired value by changing the value of the parameter. Further, according to the present invention, one coefficient data is selected from a plurality of coefficient data candidates corresponding to the parameter value and used by the feature quantity related to the high-frequency component quantity around the target position in the second image signal. Therefore, it is possible to prevent occurrence of a portion having an inappropriate resolution in the image based on the second image signal, and to improve the image quality.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a television receiver as an embodiment.
FIG. 2 is a block diagram showing a configuration of a coefficient selection circuit.
FIG. 3 is a diagram for explaining a dynamic range DR constituting a feature amount;
FIG. 4 is a diagram for explaining an activity ACT constituting a feature amount;
FIG. 5 is a diagram showing a model of a dynamic range and activity detection part;
FIG. 6 is a diagram illustrating a histogram model of feature amounts corresponding to all SD pixels in one field.
FIG. 7 is a diagram illustrating an example of a location in each feature amount area in a screen and a degree of failure.
FIG. 8 is a diagram schematically illustrating resolution selection information in a ROM included in a coefficient selection signal generation unit.
FIG. 9 is a diagram for explaining a change in coefficient data used at each location in the screen with respect to a change in the value of a parameter Q indicating resolution.
FIG. 10 is a block diagram illustrating a configuration of a coefficient data generation apparatus.
FIG. 11 is a block diagram illustrating a configuration example of an image signal processing device to be realized by software.
FIG. 12 is a flowchart showing a procedure of image signal processing.
FIG. 13 is a diagram for explaining a pixel position relationship between a 525i signal and a 1050i signal.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Television receiver, 101 ... System controller, 102 ... Remote control signal receiving circuit, 105 ... Receiving antenna, 106 ... Tuner, 109 ... Buffer memory, 110 ... Image signal Processing unit 111 ... Display unit 121 ... First tap selection circuit 122 ... Second tap selection circuit 123 ... Third tap selection circuit 124 ... Spatial class detection Circuit 125... Motion class detection circuit 126... Class synthesis circuit 127... Estimation prediction calculation circuit 128 .. post-processing circuit 131 .. coefficient memory 132. ,..., Coefficient selection circuit, 141, feature amount detection unit, 142, feature amount memory, 143, feature amount region determination unit, 144, region detection unit, 145 .. Coefficient selection signal generation unit 150... Coefficient data generation device 151... Input terminal 152... SD signal generation circuit 153... First tap selection circuit 154. Tap selection circuit, 155 ... third tap selection circuit, 157 ... space class detection circuit, 158 ... motion class detection circuit, 159 ... class synthesis circuit, 160 ... normal equation generation unit 161 ... Coefficient data determining unit 162 ... Coefficient memory 200 ... Remote control transmitter 300 ... Image signal processing device 301 ... CPU 302 ... ROM 303 ... RAM, 304 ... bus, 305 ... hard disk drive, 307 ... floppy (R) disk drive, 308 ... communication unit, 309, 312, 313, 316, 317, Interface, 310 ... remote control signal reception circuit, 311 ... display, 314 ... input terminal, 315 ... output terminal, 400 ... communication network

Claims (23)

An image signal processing device that converts a first image signal composed of a plurality of pixel data into a second image signal composed of a plurality of pixel data,
First data selection means for selecting a plurality of first pixel data located around a target position in the second image signal based on the first image signal;
Feature amount detection means for detecting a feature amount related to the amount of high frequency components around the position of interest based on a plurality of first pixel data selected by the first data selection means;
Resolution parameter output means for outputting a parameter indicating the resolution of the image based on the second image signal;
Pixel data generating means for generating pixel data at a position of interest in the second image signal corresponding to the feature quantity detected by the feature quantity detection means and the parameter output from the resolution parameter output means; An image signal processing apparatus. The pixel data generation means includes
Coefficient data candidate generating means for generating coefficient data candidates of the estimation formula for a plurality of representative resolutions corresponding to the parameters output from the resolution parameter output means;
A resolution specifying unit for specifying one of the plurality of representative resolutions based on the feature amount detected by the feature amount detection unit and the parameter output from the resolution parameter output unit;
Coefficient data selecting means for selecting coefficient data corresponding to the resolution specified by the resolution specifying means from the coefficient data candidates generated by the coefficient data candidate generating means;
Second data selection means for selecting a plurality of second pixel data located around a target position in the second image signal based on the first image signal;
The pixel data of the target position is calculated based on the estimation formula using the plurality of second pixel data selected by the second data selection unit and the coefficient data selected by the coefficient data selection unit. The image signal processing apparatus according to claim 1, further comprising a calculation unit. Third data selection means for selecting a plurality of third pixel data located around the position of interest in the second image signal based on the first image signal;
Class detecting means for detecting a class to which the pixel data of the target position belongs based on a plurality of third pixel data selected by the third data selecting means;
The coefficient data candidate generating means generates the coefficient data candidates for each class,
The coefficient data selecting means selects coefficient data corresponding to the resolution specified by the resolution specifying means and the class detected by the class detecting means from the coefficient data candidates generated by the coefficient data candidate generating means. The image signal processing apparatus according to claim 2, wherein: The resolution specifying means is:
Detecting means for detecting a feature quantity region including a feature quantity detected by the feature quantity detection means among a plurality of feature quantity areas determined based on the feature quantity detected over the entire screen;
Storage means for storing resolution selection information in the plurality of feature amount regions corresponding to each value of the parameter;
The value of the parameter output from the resolution parameter output means and the resolution selection information corresponding to the feature amount area detected by the detection means are extracted from the storage means, and the one resolution is specified based on the resolution selection information. The image signal processing apparatus according to claim 2, further comprising a specifying unit. The feature amount detection means includes:
A feature amount related to the high-frequency component amount is obtained using an absolute value sum of adjacent pixels in the plurality of first pixel data and a dynamic range in the plurality of first pixel data. The image signal processing apparatus according to claim 1. The resolution parameter output means includes
The image signal processing apparatus according to claim 1, wherein a parameter indicating the resolution is generated by a key input operation. The resolution parameter output means includes
The image signal processing apparatus according to claim 1, wherein a parameter indicating the resolution is generated by rotating a knob. Image signal input means for inputting a first image signal composed of a plurality of pixel data;
Image signal processing means for converting the first image signal input from the image signal input means into a second image signal composed of a plurality of pixel data and outputting the second image signal;
Image display means for displaying an image based on the second image signal output from the image signal processing means on an image display element;
Resolution parameter output means for outputting a parameter indicating the resolution of the image by the second image signal,
The image signal processing means includes:
First data selection means for selecting a plurality of first pixel data located around a target position in the second image signal based on the first image signal;
Feature amount detection means for detecting a feature amount related to the amount of high frequency components around the position of interest based on a plurality of first pixel data selected by the first data selection means;
Pixel data generating means for generating pixel data of a target position in the second image signal corresponding to the feature amount detected by the feature amount detecting means and the parameter output from the resolution parameter output means; An image display device characterized by the above. The pixel data generation means includes
Coefficient data candidate generating means for generating coefficient data candidates of the estimation formula for a plurality of representative resolutions corresponding to the parameters output from the resolution parameter output means;
A resolution specifying unit for specifying one of the plurality of representative resolutions based on the feature amount detected by the feature amount detection unit and the parameter output from the resolution parameter output unit;
Coefficient data selecting means for selecting coefficient data corresponding to the resolution specified by the resolution specifying means from the coefficient data candidates generated by the coefficient data candidate generating means;
Second data selection means for selecting a plurality of second pixel data located around a target position in the second image signal based on the first image signal;
The pixel data of the target position is calculated based on the estimation formula using the plurality of second pixel data selected by the second data selection unit and the coefficient data selected by the coefficient data selection unit. The image display apparatus according to claim 8, further comprising a calculation unit. Third data selection means for selecting a plurality of third pixel data located around the position of interest in the second image signal based on the first image signal;
Class detecting means for detecting a class to which the pixel data of the target position belongs based on a plurality of third pixel data selected by the third data selecting means;
The coefficient data candidate generating means generates the coefficient data candidates for each class,
The coefficient data selecting means selects coefficient data corresponding to the resolution specified by the resolution specifying means and the class detected by the class detecting means from the coefficient data candidates generated by the coefficient data candidate generating means. The image display device according to claim 9. The resolution specifying means is:
Detecting means for detecting a feature quantity region including a feature quantity detected by the feature quantity detection means among a plurality of feature quantity areas determined based on the feature quantity detected over the entire screen;
Storage means for storing resolution selection information in the plurality of feature amount regions corresponding to each value of the parameter;
The value of the parameter output from the resolution parameter output means and the resolution selection information corresponding to the feature amount area detected by the detection means are extracted from the storage means, and the one resolution is specified based on the resolution selection information. The image display apparatus according to claim 9, further comprising a specifying unit. The feature amount detection means includes:
A feature amount related to the high-frequency component amount is obtained using an absolute value sum of adjacent pixels in the plurality of first pixel data and a dynamic range in the plurality of first pixel data. The image display device according to claim 8. The resolution parameter output means includes
9. The image display device according to claim 8, wherein a parameter indicating the resolution is generated by a key input operation. The resolution parameter output means includes
9. The image display device according to claim 8, wherein a parameter indicating the resolution is generated by rotating the knob. An image signal processing method for converting a first image signal composed of a plurality of pixel data into a second image signal composed of a plurality of pixel data,
A first step of selecting a plurality of first pixel data located around a target position in the second image signal based on the first image signal;
A second step of detecting a feature amount related to a high-frequency component amount around the position of interest based on the plurality of first pixel data selected in the first step;
A third step of outputting a parameter indicating the resolution of the image based on the second image signal;
A fourth step of generating pixel data of a target position in the second image signal corresponding to the feature amount detected in the second step and the parameter output in the third step. An image signal processing method characterized by the above. The fourth step is
Generating coefficient data candidates of the estimation formula for a plurality of representative resolutions corresponding to the parameters output in the third step;
Identifying one of the plurality of representative resolutions based on the feature amount detected in the second step and the parameter output in the third step;
Selecting coefficient data corresponding to the identified resolution from the generated coefficient data candidates;
Selecting a plurality of second pixel data located around a target position in the second image signal based on the first image signal;
16. The method of calculating pixel data of the target position based on the estimation formula using the selected plurality of second pixel data and the selected coefficient data. 2. An image signal processing method according to 1. A fifth step of selecting a plurality of third pixel data located around the position of interest in the second image signal based on the first image signal;
A sixth step of detecting a class to which the pixel data of the target position belongs based on the plurality of third pixel data selected in the fifth step;
In the step of generating the coefficient data candidates, the coefficient data candidates are generated for each class,
17. The image signal processing method according to claim 16, wherein, in the step of selecting the coefficient data, coefficient data corresponding to the identified resolution and the class detected in the sixth step is selected. In the step of specifying the resolution,
A feature amount region including the feature amount detected in the second step is detected from a plurality of feature amount regions determined based on the feature amount detected over the entire screen;
The value of the parameter output in the third step and the resolution selection information corresponding to the detected feature amount region from the memory storing the resolution selection information in the plurality of feature amount regions corresponding to each value of the parameter Take out
The image signal processing method according to claim 16, further comprising: specifying one of the plurality of representative resolutions based on the extracted resolution selection information. In the second step,
A feature amount related to the high-frequency component amount is obtained using an absolute value sum of adjacent pixels in the plurality of first pixel data and a dynamic range in the plurality of first pixel data. The image signal processing method according to claim 15. In the third step,
16. The image signal processing method according to claim 15, wherein a parameter indicating the resolution is generated by a key input operation. In the third step,
16. The image signal processing method according to claim 15, wherein a parameter indicating the resolution is generated by rotating the knob. In order to convert a first image signal composed of a plurality of pixel data into a second image signal composed of a plurality of pixel data,
A first step of selecting a plurality of first pixel data located around a target position in the second image signal based on the first image signal;
A second step of detecting a feature amount related to a high-frequency component amount around the position of interest based on the plurality of first pixel data selected in the first step;
A third step of outputting a parameter indicating the resolution of the image based on the second image signal;
An image having a fourth step of generating pixel data of a target position in the second image signal corresponding to the feature amount detected in the second step and the parameter output in the third step A computer-readable medium storing a program for causing a computer to execute a signal processing method. In order to convert a first image signal composed of a plurality of pixel data into a second image signal composed of a plurality of pixel data,
A first step of selecting a plurality of first pixel data located around a target position in the second image signal based on the first image signal;
A second step of detecting a feature amount related to a high-frequency component amount around the position of interest based on the plurality of first pixel data selected in the first step;
A third step of outputting a parameter indicating the resolution of the image based on the second image signal;
An image having a fourth step of generating pixel data of a pixel of interest in the second image signal corresponding to the feature amount detected in the second step and the parameter output in the third step A program for causing a computer to execute a signal processing method.

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