JP4015010B2 - Image processing apparatus, image forming apparatus, image processing method, program for realizing the image processing method, and recording medium storing the program - Google Patents

Description

この映像信号ＮＳＴＣを復調するに際し、Ｃ信号からＩＱ成分を分離する必要がある。ＮＴＳＣ方式では、カラーサブキャリア周波数ｆscの整数倍のサンプリング周波数でＣ信号をサンプリングすることにより、Ｃ信号をＩＱ成分に復調している。カラーサブキャリア周波数ｆscの４倍のサンプリング周波数をＮＴＳＣ-４ｆscと称している。このサンプリング周波数ＮＴＳＣ-４ｆscでＣ信号をサンプリングすることにより、次の関係式（２）に示す様なＩ、Ｑ、−Ｉ、−Ｑを復調することができる。
【００５８】
【数２】

従って、ＹＣ分離部２１によりフィールド内ライン相関に基づいてＹＣ分離されたＹ信号及びＣ信号には、サンプリング周波数に依存した周期でクロストークが発生する。そこで、図５に示す近傍４×１画素ブロックのＹ信号の和について、フレーム間差分値と第１及び第２フィールド間差分値を求めて、クロストークの影響を軽減する。
【００５９】
次に、図６のフローチャートに従って、フレーム間差分値と第１及び第２フィールド間差分値を求め、これらの差分値に基づいて画像の動きを検知するための処理手順を説明する。
【００６０】
まず、図７に示す様に画像から注目画素ブロックを抽出し、この注目画素ブロックのＹ信号の和について、フレーム間差分値と第１及び第２フィールド間差分値を求め、また該注目画素ブロックの左右の各画素ブロックのＹ信号の和についても、フレーム間差分値と第１及び第２フィールド間差分値を求める。そして、注目画素ブロックのフレーム間差分値と左右の各画素ブロックのフレーム間差分値の和を注目画素ブロックのフレーム間差分値として置き換えて設定し、かつ注目画素ブロックの第１及び第２フィールド間差分値と左右の各画素ブロックの第１及び第２フィールド間差分値のそれぞれの和を注目画素ブロックの第１及び第２フィールド間差分値として置き換えて設定する（ステップＳ１０１）。これにより、孤立した注目画素ブロックの動き検知精度の劣化を低減させることができる。
【００６１】
こうして設定された注目画素ブロックのフレーム間差分値と第１及び第２フィールド間差分値を比較して、フレーム間差分値が第１及び第２フィールド間差分値のいずれよりも大きいか否かを判定する（ステップＳ１０２）。そして、フレーム間差分値が第１及び第２フィールド間差分値の少なくとも一方よりも小さければ（ステップＳ１０２で「Ｙｅｓ」）、各フレーム間の相関が高いことから、注目画素ブロックを静止画素ブロックであると判定する（ステップＳ１０３）。また、フレーム間差分値が第１及び第２フィールド間差分値のいずれよりも大きければ（ステップＳ１０２で「Ｎｏ」）、フィールド間相関（垂直相関）がフレーム間相関よりも高いことから、注目画素ブロックを動画素ブロックであると判定する（ステップＳ１０４）。
【００６２】
この図６の処理は、画像の全ての各画素ブロック毎に行われ、該各画素ブロックが静止画素ブロック及び動画素ブロックのいずれであるかが判定される。
【００６３】
シーン変化判定部２４は、図８のフローチャートに従って、各フレーム間にシーン変化があるか否かを判定する。
【００６４】
まず、フラッグＦ＝０と初期化し（ステップＳ２０１）、走査線の各画素ブロックのうちの半数以上が動画素ブロックであるか否かを判定する（ステップＳ２０２）。そして、半数以上が動画素ブロックであれば（ステップＳ２０２で「Ｙｅｓ」）、シーンの変化があるものとして（ステップＳ２０３）、フラッグＦ＝ａに更新する（ステップＳ２０４）。また、半数以上が動画素ブロックでなければ（ステップＳ２０２で「Ｎｏ」）、シーンの変化がないものとして（ステップＳ２０５）、フラッグＦを更新しない。
【００６５】
そして、フラッグＦ＝ａとなったときには、フレーム間相関が殆どないため、判定の対象となった走査線のＹ信号及びＣ信号をＹＣ分離部２１から出力された状態のままで出力する。また、フラッグＦ＝０のときには、フレーム間相関があるため、判定の対象となった走査線のＹ信号及びＣ信号を補正部２３へと出力する。
【００６６】
この図８の処理は、画像の全ての各走査線毎に行われ、シーンの変化があるときには、走査線のＹ信号及びＣ信号がそのまま出力され、シーンの変化がないときには、走査線のＹ信号及びＣ信号が補正部２３に出力される。
【００６７】
補正部２３は、シーンの変化がないと判定された走査線のＹ信号及びＣ信号を入力すると、該走査線の各画素ブロックを順次処理する。例えば、画素ブロックが動き検知部２２により静止画素ブロックと判定されていれば、連続する各フレームにおける該画素ブロックのＹ信号及びＣ信号の平均値を求めて出力する。つまり、画素ブロックのＹ信号及びＣ信号を補正して出力する。また、画素ブロックが動き検知部２２により動画素ブロックと判定されていれば、該画素ブロックのＹ信号及びＣ信号をＹＣ分離部２１から出力された状態のままで出力する。
【００６８】
次に、図９のフローチャートに従って、ＹＣ分離手段１２Ａによる一連の処理を説明する。
【００６９】
まず、コンポジットカラーテレビジョン信号をＹＣ分離部２１によりＹ信号及びＣ信号に分離し（ステップＳ３０１）、１走査線の各画素ブロック別に、フィールド間相関及びフレーム間相関を用いて画像の動きを動き検知部２２により検知し（ステップＳ３０２）、１走査線についての処理が終了するまで（ステップＳ３０３で「Ｙｅｓ」）、各ステップＳ３０１，Ｓ３０２を繰り返し、この後に、シーン変化判定部２４による処理に移って（ステップＳ３０４）、１走査線について、連続する各フレーム間にシーン変化があるか否かを判定する（ステップＳ３０５）。そして、１走査線についてシーン変化がなければ（ステップＳ３０５で「Ｎｏ」）、１走査線の各画素ブロック別に、画素ブロックが動画素ブロックであるか否かを判定し（ステップＳ３０６）、画素ブロックが動画素ブロックでなければ（ステップＳ３０６で「Ｎｏ」）、該画素ブロックのＹ信号及びＣ信号を補正部２３により補正して出力し（ステップＳ３０７）、また画素ブロックが動画素ブロックであれば（ステップＳ３０６で「Ｙｅｓ」）、ＹＣ分離部２１によりフィールド内走査線間相関を用いて分離された該画素ブロックのＹ信号及びＣ信号をそのまま出力する（ステップＳ３０８）。また、１走査線についてシーン変化があれば（ステップＳ３０５で「Ｙｅｓ」）、ＹＣ分離部２１によりフィールド内走査線間相関を用いて分離された該走査線のＹ信号及びＣ信号をそのまま出力する（ステップＳ３０８）。
【００７０】
これらのステップＳ３０１〜Ｓ３０８は、画像の全ての走査線並びに全ての画素ブロックについての処理が終了するまで繰れ返される（ステップＳ３０９）。
【００７１】
尚、図２のＹＣ分離手段１２による処理過程は、図９のフローチャートの各ステップＳ３０４，Ｓ３０５を省略したものである。
【００７２】
この様に本実施形態では、コンポジットカラーテレビジョン信号をＹＣ分離部２１によりＹ信号及びＣ信号に分離し、フィールド間相関及びフレーム間相関を用いて画像の動きを動き検知部２２により検知し、この画像の動きに基づいてフレーム間にシーン変化があるか否かをシーン変化判定部２４により判定し、画像の動きがなく、かつシーン変化がなければ、Ｙ信号及びＣ信号を補正部２３により補正して出力し、シーン変化があったり、画像の動きがあれば、ＹＣ分離部２１により分離されたＹ信号及びＣ信号をそのまま出力し、これによりＹ信号及びＣ信号の分離精度を向上させている。また、２フレーム分の映像信号を記憶するメモリ容量だけで、一連の処理が可能であり、メモリの大容量化を招かずに済む。
【００７３】
尚、Ｙ信号と同様に、Ｃ信号を用いることによっても動き検知を行うことができ、この動き検知結果に基づいてＹ信号及びＣ信号を補正しても良い。あるいは、Ｙ信号及びＣ信号を共に用いて動き検知を行い、この動き検知結果に基づいてＹ信号及びＣ信号を補正しても構わない。また、各演算値に適宜の重み付け等を行ったり、各値の和の代わりに、該各値の平均値を用いても良い。
【００７４】
図１０は、本発明の画像処理装置の第２実施形態におけるＹＣ分離手段を示すブロック図である。本実施形態の画像処理装置は、図２のＹＣ分離手段１２又は図３のＹＣ分離手段１２Ａの代わりに、図１０のＹＣ分離手段１２Ｂを適用したものである。
【００７５】
本実施形態のＹＣ分離手段１２Ｂでは、図３の動き検知部２２の代わりに、第１動き検知部３１及び第２動き検知部３２をシーン変化判定部２４の前後に挿入している。
【００７６】
ＹＣ分離部２１は、コンポジットカラーテレビジョン信号に対してフィールド内走査線間相関（垂直相関）を用いたＹＣ分離処理を行うことにより、コンポジットカラーテレビジョン信号をＹ信号及びＣ信号に分離する。
【００７７】
第１動き検知部３１は、ＹＣ分離部２１によって分離されたＹ信号を１フレーム分遅延させ、この遅延された１フレーム分のＹ信号及び該フレームに引き続く次の１フレーム分のＹ信号を用いて、Ｙ信号についてのフレーム間相関を求め、このフレーム間相関に基づいて画像の動きを検知する。
【００７８】
ここでは、Ｙ信号について、第１フレームにおける偶数フィールドと第２フレームにおける偶数フィールドの差の絶対値、第１フレームにおける奇数フィールドと第２フレームにおける奇数フィールドの差の絶対値、及び第１フレームにおける偶数フィールド及び第２フレームにおける奇数フィールドの和と第１フレームにおける奇数フィールド及び第２フレームにおける偶数フィールドの和との差の絶対値を求め、更に該各絶対値の和を求めて、この和をフレーム間相関を示すフレーム間差分値として用い、このフレーム間差分値に基づいて画像の動きを検知している。
【００７９】
図１１のフローチャートにしたがって、第１動き検知部３１のより具体的な処理過程を説明する。
【００８０】
まず、４×１の注目画素ブロックを抽出し、この注目画素ブロックのＹ信号の和について、フレーム間差分値を求め、また該注目画素ブロックの左右の各画素ブロックのＹ信号の和についても、フレーム間差分値を求める。そして、注目画素ブロックのフレーム間差分値と左右の各画素ブロックのフレーム間差分値の和を注目画素ブロックのフレーム間差分値として置き換えて設定する（ステップＳ４０１）。
【００８１】
次に、注目画素ブロックのフレーム間差分値と予め設定された閾値（例えば４８）を比較して、フレーム間差分値が閾値よりも小さいか否かを判定する（ステップＳ４０２）。そして、フレーム間差分値が閾値よりも小さければ（ステップＳ４０２で「Ｙｅｓ」）、各フレーム間の相関が高いことから、注目画素ブロックを静止画素ブロックであると判定する（ステップＳ４０３）。また、フレーム間差分値が閾値よりも小さくなければ（ステップＳ４０２で「Ｎｏ」）、各フレーム間の相関が低いことから、注目画素ブロックを動画素ブロックであると判定する（ステップＳ４０４）。
【００８２】
この図１１の処理は、画像の全ての各画素ブロック毎に行われ、該各画素ブロックが静止画素ブロック及び動画素ブロックのいずれであるかが判定される。
【００８３】
シーン変化判定部２４は、第１動き検知部３１の検知結果に基づいて、走査線の各画素ブロックのうちの半数以上が動画素ブロックであるか否かを判定する。そして、半数以上が動画素ブロックであれば、シーンの変化があり、フレーム間相関が殆どないため、判定の対象となった走査線のＹ信号及びＣ信号をＹＣ分離部２１から出力された状態のままで出力する。また、半数以上が動画素ブロックでなければ、シーンの変化がなく、フレーム間相関があるため、走査線のＹ信号及びＣ信号を第２動き検知部３２に出力する。
【００８４】
第２動き検知部３２は、ＹＣ分離部２１によって分離された連続する２フレーム分のＹ信号を用いて、フィールド間相関を求め、このフィールド間相関及び第１動き検知部３１により求められたフレーム間相関に基づいて、各画素ブロック別に動きを検知する。
【００８５】
フィールド間相関に関しては、Ｙ信号について、第１フレームにおける各フィールド間の差の絶対値にオフセット値（例えば１６）を加えた値を求めて、この値を第１フィールド間差分値として用い、第２フレームにおける各フィールド間の差の絶対値にオフセット値（例えば１６）を加えた値を求めて、この値を第２フィールド間差分値として用いる。
【００８６】
ここでは、画像から注目画素ブロックを抽出し、この注目画素ブロックのＹ信号の和について、第１及び第２フィールド間差分値を求め、また該注目画素ブロックの左右の各画素ブロックのＹ信号の和についても、第１及び第２フィールド間差分値を求める。そして、注目画素ブロックの第１及び第２フィールド間差分値と左右の各画素ブロックの第１及び第２フィールド間差分値のそれぞれの和を注目画素ブロックの第１及び第２フィールド間差分値として置き換えて設定する。
【００８７】
そして、第１動き検知部３１により求められた注目画素ブロックのフレーム間差分値と該注目画素ブロックの第１及び第２フィールド間差分値とを比較し、フレーム間差分値が第１及び第２フィールド間差分値の少なくとも一方よりも小さければ、各フレーム間の相関が高いことから、注目画素ブロックを静止画素ブロックであると判定する。また、フレーム間差分値が第１及び第２フィールド間差分値のいずれよりも大きければ、フィールド間相関（垂直相関）がフレーム間相関よりも高いことから、注目画素ブロックを動画素ブロックであると判定する。
【００８８】
この様な処理を画像の全ての各画素ブロック毎に行い、該各画素ブロックが静止画素ブロック及び動画素ブロックのいずれであるかを判定する。
【００８９】
補正部２３は、画素ブロックが第２動き検知部３２により静止画素ブロックと判定されていれば、連続する各フレームにおける該画素ブロックのＹ信号及びＣ信号の平均値を求めて出力する。つまり、画素ブロックのＹ信号及びＣ信号を補正して出力する。また、画素ブロックが第２動き検知部３２により動画素ブロックと判定されていれば、該画素ブロックのＹ信号及びＣ信号をＹＣ分離部２１から出力された状態のままで出力する。
【００９０】
次に、図１２のフローチャートに従って、ＹＣ分離手段１２Ｂによる一連の処理を説明する。
【００９１】
まず、コンポジットカラーテレビジョン信号をＹＣ分離部２１によりＹ信号及びＣ信号に分離し（ステップＳ５０１）、１走査線の各画素ブロック別に、フレーム間相関を用いて画像の動きを第１動き検知部３１により検知し（ステップＳ５０２）、１走査線についての処理が終了するまで（ステップＳ５０３で「Ｙｅｓ」）、各ステップＳ５０１，Ｓ５０２を繰り返し、この後に、シーン変化判定部２４による処理に移って（ステップＳ５０４）、１走査線について、連続する各フレーム間にシーン変化があるか否かを判定する（ステップＳ５０５）。そして、１走査線についてシーン変化がなければ（ステップＳ５０５で「Ｎｏ」）、１走査線の各画素ブロック別に、フィールド間相関及びフレーム間相関を用いて画像の動きを第２動き検知部３２により検知し（ステップＳ５０６）、動画素ブロックでなければ（ステップＳ５０７で「Ｎｏ」）、該画素ブロックのＹ信号及びＣ信号を補正部２３により補正して出力し（ステップＳ５０８）、また動画素ブロックであれば（ステップＳ５０７で「Ｙｅｓ」）、ＹＣ分離部２１によりフィールド内走査線間相関を用いて分離された該画素ブロックのＹ信号及びＣ信号をそのまま出力する（ステップＳ５０９）。また、１走査線についてシーン変化があれば（ステップＳ５０５で「Ｙｅｓ」）、ＹＣ分離部２１によりフィールド内走査線間相関を用いて分離された該走査線のＹ信号及びＣ信号をそのまま出力する（ステップ５０９）。
【００９２】
これらのステップＳ５０１〜Ｓ５０９は、画像の全ての走査線並びに全ての画素ブロックについての処理が終了するまで繰れ返される（ステップＳ５１０）。
【００９３】
この様に本実施形態では、コンポジットカラーテレビジョン信号をＹ信号及びＣ信号に分離し、フレーム間相関を用いて画像の動きを第１動き検知部３１により検知し、この画像の動きに基づいてフレーム間にシーン変化があるか否かを判定し、シーン変化があれば、ＹＣ分離部２１により分離されたＹ信号及びＣ信号をそのまま出力している。また、シーン変化がなければ、フィールド間相関及びフレーム間相関を用いて画像の動きを第２動き検知部３２により再び検知し、画像の動きがあれば、ＹＣ分離部２１により分離されたＹ信号及びＣ信号をそのまま出力し、また画像の動きがなければ、Ｙ信号及びＣ信号を補正部２３により補正して出力し、これによりＹ信号及びＣ信号の分離精度を向上させている。
【００９４】
従って、常に、第１動き検知部３１による動きの検知が行われ、シーン変化がないときにだけ、第２動き検知部３２による動きの検知が行われる。これにより、一連の動きの検知処理速度を向上させることができる。更に、シーン変化がなく、画像の動きもないときにだけ、補正部２３による補正を行っているので、この補正処理を簡単化することができる。
【００９５】
また、２フレーム分の映像信号を記憶するメモリ容量だけで、一連の処理が可能であり、メモリの大容量化を招かずに済む。
【００９６】
尚、Ｙ信号と同様に、Ｃ信号を用いることによっても動き検知を行うことができ、この動き検知結果に基づいてＹ信号及びＣ信号を補正しても良い。あるいは、Ｙ信号及びＣ信号を共に用いて動き検知を行い、この動き検知結果に基づいてＹ信号及びＣ信号を補正しても構わない。また、各演算値に適宜の重み付け等を行ったり、各値の和の代わりに、該各値の平均値を用いても良い。
【００９７】
また、本発明は、画像処理方法を実現するためのプログラムをＣＰＵ等のハードウェアあるいはコンピュータ等により実行することによりなされる。従って、本発明は、画像処理装置だけではなく、画像処理方法、その方法を実施するためのプログラム、及びそのプログラムを記憶した記録媒体を包含する。また、本発明は、画像処理装置を適用した画像形成装置をも包含する。画像形成装置としては、ＣＲＴ、液晶ディスプレイ、プリンタ等がある。
【００９８】
プログラムは、磁気ディスク、光ディスク、コンピュータに内蔵のハードディスク等の記録媒体に記録されたり、通信ネットワークを通じて送受される。コンピュータやマイクロプロセッサ内蔵の端末装置等は、プログラムを記録媒体から読み出したり、プログラムをインターネット等の通信ネットワークを通じて受信し、このプログラムを実行して、本発明を実施することができる。プログラムをインターネット等の通信ネットワークを通じて受信する場合は、ダウンロード用のプログラムが必要になる。このダウンロード用のプログラムも、磁気ディスク、光ディスク、コンピュータに内蔵のハードディスク等の記録媒体に記録されたり、通信ネットワークを通じて送受される。また、これらのプログラムをインターネットを通じて定期的に端末装置にダウンロードすることもできる。
【００９９】
更に、コンピュータ等の端末装置及びネットワーク等からなるシステムにおいては、複数の処理をコンピュータ等の端末装置に分散して行い得る。従って、プログラムは、コンピュータ等の単一の端末装置だけではなく、システムにも適用し得る。このシステムは、テレビジョン、ビデオカメラ、パーソナルコンピュータ、ＣＲＴ、液晶ディスプレイ、プリンタ、サーバ等をネットワークを通じて接続したものである。ネットワークとしては、インターネット、ＬＡＮ等がある。
【０１００】
記録媒体としては、マスクＲＯＭ、ＥＰＲＯＭ、ＥＥＰＲＯＭ、フラッシュＲＯＭといった半導体記憶素子、ＩＣカード、ハードディスク、フレキシブルディスク、あるいはＭＯ、ＣＤ、ＭＤ、ＤＶＤ等の光ディスク、磁気テープ等を挙げることができ、プログラムを記録することが可能であれば他の種類の記録媒体であっても良い。
【０１０１】
【発明の効果】
以上説明した様に本発明によれば、コンポジットカラーテレビジョン信号を輝度コンポーネント信号及び色コンポーネント信号に分離し、分離された輝度コンポーネント信号及び色コンポーネント信号のうちの少なくとも一方の２フレーム分を用いて、画像の動きを検知し、画像の動きがなければ、輝度コンポーネント信号及び色コンポーネント信号を補正して出力し、画像の動きがあれば、Ｙ信号及びＣ信号をそのまま出力し、これにより輝度コンポーネント信号及び色コンポーネント信号の分離精度を向上させている。また、２フレーム分の映像信号を記憶するメモリ容量だけで、一連の処理が可能であり、メモリの大容量化を招かずに済む。
【０１０２】
また、画素ブロック単位で相関を求めているので、演算処理を簡略化したり、クロストークの影響を軽減することができる。あるいは、注目画素ブロックに隣接する他の画素ブロックの相関を参照して、注目画素ブロックの相関を設定しているので、孤立した注目画素ブロックの動き検知精度の劣化を低減させることができる。
【０１０３】
更に、シーンの変化があると判定されたときには、輝度コンポーネント信号及び色コンポーネント信号を補正部を介さずにそのまま出力しているので、補正部の処理を軽減することができ、処理速度が向上する。あるいは、シーン変化がなく、画像の動きもないときにだけ、補正処理を行っているので、この補正処理を簡単化することができる。また、走査線上の各画素ブロックに含まれる動画素ブロックの割合に応じて、走査線にシーンの変化があるか否かを判定しているので、この判定を容易に行うことができ、判定処理が簡単化される。
【図面の簡単な説明】
【図１】本発明の画像処理装置の第１実施形態を示すブロック図である。
【図２】図１の画像処理装置におけるＹＣ分離手段の構成を示すブロック図である。
【図３】図１の画像処理装置におけるＹＣ分離手段の他の構成例を示すブロック図である。
【図４】色コンポーネント信号についての第１及び第２フレーム間の相関を示す図である。
【図５】近傍４×１画素ブロックを模式的に示す図である。
【図６】図２及び図３のＹＣ分離手段における動き検知部による動き検知のための処理手順を示すフローチャートである。
【図７】注目画素ブロック、及び該注目画素ブロックに隣接する他の各画素ブロックを示す図である。
【図８】図３のＹＣ分離手段におけるシーン変化判定部によるシーン変化判定のための処理手順を示すフローチャートである。
【図９】図３のＹＣ分離手段によるコンポジットカラーテレビジョン信号分離のための処理手順を示すフローチャートである。
【図１０】本発明の画像処理装置の第２実施形態におけるＹＣ分離手段を示すブロック図である。
【図１１】図１０のＹＣ分離手段における第１動き検知部による処理手順を示すフローチャートである。
【図１２】図１０のＹＣ分離手段によるコンポジットカラーテレビジョン信号分離のための処理手順を示すフローチャートである。
【符号の説明】
１０ 画像処理装置
１１ 入力手段
１２，１２Ａ，１２Ｂ ＹＣ分離手段
１３ 色差復調手段
１４ フィルタ処理手段
１５ 解像度変換処理手段
１６ 色変換手段
１７ ハーフトーン手段
１８ プリンタ部
２１ ＹＣ分離部
２２ 動き検知部
２３ 補正部
２４ シーン変化判定部
３１ 第１動き検知部
３２ 第２動き検知部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus, an image forming apparatus, an image processing method, a program for realizing the image processing method, and a program for realizing the image processing method for separating and processing a composite color television signal into a luminance component signal and a color component signal The present invention relates to a stored recording medium.
[0002]
[Prior art]
In recent years, color television signals have been processed in various ways in order to improve the quality of color television images. A composite color television signal such as a general NTSC (National Television System Committee) system and a PAL (Phase Alternating Line) system is a luminance component signal (hereinafter referred to as Y signal) or a color component signal (hereinafter referred to as C signal). Multiplexed signals are transmitted and received in a multiplexed state. For this reason, on the receiving side, it is necessary to separate the composite color television signal into a Y signal and a C signal.
[0003]
The composite color television signal is constructed by multiplexing the C signal in the high frequency region of the Y signal, and in order to separate the low frequency component Y signal and the high frequency component C signal, a horizontal bandpass. Filters are widely used. However, when a horizontal band-pass filter is used, a decrease in horizontal resolution occurs, or color bleeding called crosstalk occurs due to a part of the Y signal being erroneously treated as a C signal. It was easy.
[0004]
For this reason, recently, comb filters are often used which do not cause a decrease in horizontal resolution. However, when this comb filter is used, the correlation in the vertical direction of the C signal becomes low, and if a high-frequency component in the vertical direction exists, this leaks into the Y signal and causes crosstalk.
[0005]
Therefore, instead of separating the Y signal and the C signal by such a filter, the Y signal and the C signal are obtained by utilizing the intra-field scanning line correlation and the inter-frame correlation inherent in the Y signal and the C signal (video signal). A method of separating the two has been proposed.
[0006]
In the composite color television signal, in both the odd field and the even field, if attention is paid to the phase of the video signal between adjacent scanning lines in the field, the Y signal has the same phase and the C signal has the opposite phase. ing. If attention is paid to the amplitude of the video signal between adjacent scanning lines in the field, both the Y signal and the C signal have a correlation. Therefore, when the sum of the video signals between adjacent scanning lines is obtained, the amplitude of the Y signal is doubled and the C signal is substantially canceled. Further, when the difference between the video signals between the adjacent scanning lines is obtained, the Y signal is substantially canceled and the amplitude of the C signal is doubled. Therefore, 1/2 of these sums and differences can be obtained as Y signal and C signal.
[0007]
Also, between the odd fields of each successive frame and between the even fields of each frame, the Y signal has the same phase, the C signal has the opposite phase, the Y signal has a correlation, and the C signal has a correlation. . For this reason, when the sum of the video signals is obtained for each odd-numbered field and even-numbered field of each successive frame, the amplitude of the Y signal is doubled, the C signal is substantially canceled, and the difference between the video signals is obtained. As a result, the Y signal is substantially canceled, and the amplitude of the C signal is doubled. Therefore, 1/2 of these sums and differences can be obtained as Y signal and C signal.
[0008]
In this way, the Y signal and the C signal can be separated by using either the correlation between adjacent scanning lines in the field or the correlation between consecutive frames.
[0009]
However, regardless of which correlation is used, if the degree of correlation is high, the Y signal and the C signal can be reliably separated, but if the degree of correlation is low, the separation accuracy of the Y signal and the C signal decreases. To do. For example, for a scanning line located in the horizontal contour portion of the screen, the degree of correlation between the scanning lines including the scanning line is low, and the separation accuracy of the Y signal and the C signal is lowered. In addition, when the motion of the image between successive frames is intense, the degree of correlation between the frames decreases, so that the separation accuracy of the Y signal and the C signal decreases.
[0010]
For this reason, there is also a method in which the correlation between adjacent scanning lines in the field and the correlation between successive frames are properly used. This method weights the Y signal and C signal obtained by the correlation between the scanning lines and the Y signal and C signal obtained by the correlation between the frames, respectively. The weighting of the Y signal and C signal obtained by the correlation is increased, and when the motion of the image is large, the weighting of the Y signal and C signal obtained by the correlation between the scanning lines is increased. This is to prevent a reduction in the separation accuracy of the C signal.
[0011]
For example, in the technique described in Patent Document 1, the detection output from the inter-frame motion detection circuit, the inter-field motion detection circuit, and the detection output from the inter-frame motion detection circuit and the detection output from the inter-field motion detection circuit are fetched and detected. It is equipped with a motion signal mixing circuit that mixes the output and a motion detection control circuit that determines the mixing condition by the motion signal mixing circuit, and detects motion by mixing motion between frames and motion between fields Using the difference between the output of one scanning line of the motion signal mixing circuit and the output of one scanning line delayed by one field to improve the accuracy, the mixing condition by the motion signal mixing circuit is determined. The separation accuracy of the Y signal and the C signal is improved.
[0012]
[Patent Document 1]
Japanese Patent No. 3040251
[0013]
[Problems to be solved by the invention]
However, in the technique disclosed in the above publication, in order to determine the mixing condition on the top, it is necessary to provide a memory for storing the video signal for two frames in order to detect the motion between the frames. In addition, since a memory for delaying the output of the motion signal mixing circuit by one field is required, there is a problem that the capacity of the memory increases.
[0014]
Accordingly, the present invention has been made in view of the above-described conventional problems, and provides an image processing apparatus capable of improving the separation accuracy of a Y signal and a C signal without increasing the capacity of a memory. The purpose is to do.
[0015]
Further, the present invention provides not only an image processing apparatus, but also an image forming apparatus including the image processing apparatus, an image processing method, a program for realizing the image processing method, and a recording medium storing the program. With the goal.
[0016]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides an image processing apparatus including a YC separation processing unit that inputs a composite color television signal indicating an image and separates the composite color television signal into a luminance component signal and a color component signal. The YC separation processing means uses the intra-field scanning line correlation to separate the composite color television signal into the luminance component signal and the color component signal, and the separated luminance component signal and color component signal. Using at least one of the two frames, a motion detection unit that detects the motion of the image, and whether to perform correction processing of the luminance component signal or the color component signal based on the detected motion of the image And decided to perform correction processing If outputs from the corrected luminance component signal and the chrominance component signals, when it is determined that no correction processing, and a correcting section that outputs the luminance component signal and the chrominance component signals.
[0017]
According to the present invention having such a configuration, a composite color television signal is separated into a luminance component signal and a color component signal, and at least two frames of the separated luminance component signal and color component signal are used. If the image motion is detected, if there is no image motion, the luminance component signal and the color component signal are corrected and output. If there is an image motion, the Y signal and the C signal are output as they are. The separation accuracy of the component signal and the color component signal is improved. In addition, a series of processing is possible only with the memory capacity for storing the video signals for two frames, and it is not necessary to increase the memory capacity.
[0018]
Further, in the present invention, the motion detection unit, for at least one of the luminance component signal and the color component signal, adds the even field in the first frame and the odd field in the second frame and the odd field and the first frame in the first frame. The absolute value of the difference between the sum of the even fields in the two frames, the absolute value of the difference between the even fields in the first frame and the even fields in the second frame, and the difference between the odd fields in the first frame and the odd fields in the second frame. Absolute values are obtained, and these absolute values are used as inter-frame correlations to detect image motion.
[0019]
Here, in particular, the absolute value of the difference between the sum of the even field in the first frame and the odd field in the second frame and the sum of the odd field in the first frame and the even field in the second frame is used as part of the interframe correlation. Since the movement of the image is detected, it is possible to accurately detect the movement of the image even if the color component signal leaks into the luminance component signal (even if crosstalk occurs).
[0020]
Furthermore, in the present invention, the motion detection unit obtains the sum or average value of the pixel blocks for each pixel block composed of a plurality of pixels for at least one of the luminance component signal and the color component signal, and Using the average value, the inter-frame correlation is obtained for each pixel block.
[0021]
If the inter-frame correlation is obtained for each pixel block in this way, the arithmetic processing can be simplified and the influence of crosstalk can be reduced.
[0022]
In the present invention, the motion detection unit obtains the sum or average value of the inter-frame correlation of the pixel block of interest and the inter-frame correlation of other pixel blocks adjacent to the pixel block of interest, and pays attention to this sum or average value. It is replaced as the inter-frame correlation of the pixel block.
[0023]
As a result, it is possible to reduce deterioration in motion detection accuracy of the isolated pixel block of interest.
[0024]
Furthermore, in the present invention, the motion detection unit obtains an absolute value of a difference between fields in a frame for at least one of a luminance component signal and a color component signal, and uses the absolute value as a correlation between fields to obtain an image. Detecting movement.
[0025]
The motion of the image can be detected also by such inter-field correlation.
[0026]
In the present invention, the motion detection unit obtains the sum or average value of the pixel blocks for each pixel block including a plurality of pixels for at least one of the luminance component signal and the color component signal, and The inter-field correlation is obtained for each pixel block using the average value.
[0027]
Thus, if the correlation between fields is calculated | required per pixel block, a calculation process can be simplified or the influence of crosstalk can be reduced.
[0028]
Further, in the present invention, the motion detection unit obtains the sum or average value of the inter-field correlation of the pixel block of interest and the inter-field correlation of other pixel blocks adjacent to the pixel block of interest, and pays attention to this sum or average value. It is replaced as the inter-field correlation of the pixel block.
[0029]
As a result, it is possible to reduce deterioration in motion detection accuracy of the isolated pixel block of interest.
[0030]
The present invention further includes a scene change determination unit that determines whether or not there is a change in the scene of the image based on the motion of the image detected by the motion detection unit, and the scene change determination unit detects a change in the scene. When it is determined that there is a scene, the luminance component signal and the color component signal are output without passing through the correction unit, and when the scene change determination unit determines that there is no scene change, the luminance component signal and the color component signal are corrected. The output is via the part.
[0031]
By further providing the scene change determination unit in this way, the processing of the correction unit can be reduced and the processing speed is improved. Alternatively, since the correction process is performed only when there is no scene change and no image motion, this correction process can be simplified.
[0032]
Furthermore, in the present invention, the motion detection unit obtains the sum or average value of the pixel blocks for each pixel block composed of a plurality of pixels for at least one of the luminance component signal and the color component signal, and The average value is used to determine whether the pixel block is a still pixel block or a moving pixel block, and the scene change determination unit determines whether the moving pixel block is included in each pixel block on the scanning line for each scanning line of the image. It is determined whether or not there is a scene change in the scanning line in accordance with the ratio.
[0033]
Thus, if it is determined whether there is a scene change in the scanning line according to the ratio of the moving pixel block included in each pixel block on the scanning line, this determination can be easily performed, and the determination process Simplified.
[0034]
On the other hand, the present invention provides an image processing apparatus comprising YC separation processing means for inputting a composite color television signal indicating an image and separating the composite color television signal into a luminance component signal and a color component signal. Uses the intra-field scanning line correlation to separate the composite color television signal into a luminance component signal and a color component signal, and a frame for at least one of the separated luminance component signal and color component signal. A first motion detection unit that obtains an inter-correlation and detects the motion of the image using the inter-frame correlation, and whether there is a change in the scene of the image based on the motion of the image detected by the first motion detection unit A scene change determination unit that determines whether or not A second motion detection unit that obtains a correlation between fields for at least one of the degree component signal and the color component signal, and detects a motion of the image using the correlation between the fields and the inter-frame correlation obtained by the first motion detection unit And determining whether or not to correct the luminance component signal or the color component signal based on the motion of the image detected by the second motion detection unit. And a correction component that outputs the luminance component signal and the color component signal as they are, and outputs a luminance component signal and a color component signal as they are. When it is determined that the luminance component signal and the color component Signal as it is output without passing through the correcting section, when it is determined that there is no change in the scene by the scene change determination unit has a luminance component signal and the chrominance component signals output through the correction unit.
[0035]
Also according to the present invention having such a configuration, the separation accuracy of the luminance component signal and the color component signal can be improved. In addition, since the motion detection is always performed by the first motion detection unit, and the motion detection by the second motion detection unit is performed only when there is no scene change, a series of motion detection processing speed is improved. . Furthermore, a series of processing is possible only with a memory capacity for storing video signals for two frames, and it is not necessary to increase the capacity of the memory.
[0036]
The present invention includes not only an image processing apparatus but also an image forming apparatus such as a display device or a printer, an image processing method, a program for executing the method, and a recording medium storing the program.
[0037]
The program is recorded on a recording medium such as a magnetic disk, an optical disk, or a hard disk built in a computer, or transmitted and received through a communication network. A terminal device or the like with a computer or a microprocessor can implement the present invention by reading a program from a recording medium or receiving the program through a communication network and executing the program. In a system including a terminal device such as a computer and a network, a plurality of processes can be distributed to terminal devices such as a computer. Therefore, the program can be applied not only to a single terminal device such as a computer but also to a system.
[0038]
Examples of the recording medium include semiconductor storage elements such as mask ROM, EPROM, EEPROM, and flash ROM, IC cards, hard disks, flexible disks, optical disks such as MO, CD, MD, and DVD, and magnetic tapes. Other types of recording media may be used as long as they can be recorded.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0040]
FIG. 1 is a block diagram showing a first embodiment of the image processing apparatus of the present invention. In the image processing apparatus 10 of the present embodiment, a composite color television signal is input, and the composite color television signal is separated into a luminance component signal (hereinafter referred to as a Y signal) and a color component signal (hereinafter referred to as a C signal). Furthermore, these Y signal and C signal are processed, and an image indicated by these Y signal and C signal is printed out.
[0041]
The image processing apparatus 10 includes an input unit (tuner) 11 for inputting a composite color television signal, a YC separation unit 12 for separating the composite color television signal into a Y signal and a C signal, and a C signal as a Cb component signal. And a color difference demodulating means 13 for demodulating the signal into a Cr component signal, a filter processing means 14 for sharpening the Y signal, the Cb component signal, and the Cr component signal, and a resolution for performing an enlargement / reduction process on each signal. A conversion processing unit 15; a color conversion unit 16 that converts the signals into cyan, magenta, yellow, and black signals, for example, and conforms to a device color space such as a printer; and cyan, magenta, and yellow signals. And halftone means 17 for performing halftone processing. When outputting an image indicated by the Y signal and the C signal to the display device, the color conversion means converts the signal into an RGB (R: red, G: green, B: blue) signal for the display device, and displays it. A γ correction process is performed according to the γ characteristic of the apparatus, and is output as image output data. Each of the units 11 to 17 handles a digital signal and is controlled by a CPU (Central Processing Unit) or the like.
[0042]
The printer unit 18 is of an electrophotographic system or an inkjet system, and inputs cyan, magenta, yellow, and black signals from the halftone means 17 and prints an image indicated by the signals on a recording sheet. The printer unit 18 may be connected via a network, or may be a multi-function machine having a copy function. Further, instead of the printer unit 18, an image display device, a storage device, or the like may be connected.
[0043]
In the present embodiment, the YC separation means 12 is configured as shown in FIG. 2, thereby improving the separation accuracy of the Y signal and the C signal. The YC separation means 12 performs a YC separation process using the intra-field scanning line correlation (vertical correlation) on the digitized composite color television signal of each successive frame, whereby a composite color television signal is obtained. A YC separation unit 21 that separates the signal into a Y signal and a C signal, and a motion for detecting a motion of an image based on the correlation between fields and frames of the Y signal separated and extracted by the YC separation unit 21 Based on the detection unit 22 and the detected movement of the image, it is determined whether or not to correct the Y signal or the C signal. If it is determined that the correction process is to be performed, the Y signal and the C signal are corrected. And a correction unit 23 that outputs the Y signal and the C signal as they are.
[0044]
FIG. 3 shows a configuration of the YC separation unit 12A to which the scene change determination unit 24 is added.
[0045]
The scene change determination unit 24 determines whether or not there is a scene change between successive frames based on the motion of the image detected by the motion detection unit 22, and if there is no scene change, the Y signal and the C signal Is output to the correction unit 23, and if there is a scene change, the Y signal and the C signal are output as they are. Therefore, when there is no scene change, the Y signal and C signal are output through the correction unit 23, and when there is a scene change, the Y signal and C signal separated by the YC separation unit 21 using the intra-field scanning line correlation. Will be output as is.
[0046]
Next, the YC separation unit 21, the motion detection unit 22, the scene change determination unit 24, and the correction unit 23 will be described in more detail.
[0047]
The YC separation unit 21 performs YC separation processing based on the intra-field scanning line correlation. If the composite color television signal is focused on the phase of the video signal (Y signal and C signal) between adjacent scanning lines in the odd field and even field, the Y signal has the same phase, The C signal has an opposite phase. If attention is paid to the amplitude of the video signal between adjacent scanning lines in the field, both the Y signal and the C signal have a correlation. Therefore, when the sum of video signals between adjacent scanning lines is obtained, the amplitude of the Y signal is doubled and the C signal is substantially canceled. Further, when the difference between the video signals between the adjacent scanning lines is obtained, the Y signal is substantially canceled and the amplitude of the C signal is doubled. Therefore, 1/2 of these sums and differences can be obtained as Y signal and C signal.
[0048]
The motion detection unit 22 delays the Y signal separated by the YC separation unit 21 by one frame, and uses the delayed Y signal for one frame and the Y signal for the next one frame following the frame, An inter-field correlation and an inter-frame correlation for the Y signal are obtained, and image motion is detected based on the inter-field correlation and the inter-frame correlation.
[0049]
Here, regarding the inter-frame correlation, the Y signal has the same phase between the odd fields of the first and second frames and between the even fields of the first and second frames. A method is conceivable in which the difference between the Y signals is obtained for each of the odd and even fields of the two frames, and this difference is used as the inter-frame correlation.
[0050]
However, when an error occurs in the processing by the YC separation unit 21 and a part of the C signal leaks into the Y signal (when crosstalk occurs), even if the correlation between the first and second frames is high. The difference of the Y signal between the fields of the first and second frames does not become 0, and the Y signal is not completely canceled. For this reason, it is determined that the interframe correlation between the first and second frames is low, and there is motion between the first and second frames.
[0051]
Therefore, in the motion detection unit 22, with respect to the Y signal, the absolute value of the difference between the even field in the first frame and the even field in the second frame, and the absolute value of the difference between the odd field in the first frame and the odd field in the second frame. In addition, the absolute value of the difference between the sum of the even field in the first frame and the odd field in the second frame and the sum of the odd field in the first frame and the even field in the second frame is obtained. A sum of values is obtained, and this sum is used as an inter-frame difference value indicating an inter-frame correlation, and an image motion is detected based on the inter-frame difference value. As a result, even if a part of the C signal leaks into the Y signal (crosstalk occurs), it is possible to accurately detect the motion of the image.
[0052]
FIG. 4 shows the correlation between the first and second frames for the C signal. As shown in FIG. 4, the 264th scan line (even field) and the second scan line (odd field) in the first frame N, and the 264th scan line (even field) in the second frame (N + 1) and When attention is paid to the second scanning line (odd field), the C signal is in the opposite phase between the even field in the first frame N and the odd field in the second frame (N + 1), and the odd field and the second frame in the first frame N. The C signal has an opposite phase even between even fields in (N + 1). Therefore, even if a part of the C signal is mixed in the Y signal, if the sum of the even field in the first frame and the odd field in the second frame is obtained for the Y signal, the Y signal is only doubled. Rather, the mixed C signal is canceled, and if the sum of the odd field in the first frame and the even field in the second frame is calculated, the Y signal is not only doubled, but the mixed C signal is also canceled. The Therefore, the absolute value of the difference between these sums does not reflect crosstalk and indicates the correlation between the first and second frames. Of course, the 265th and subsequent scanning lines in the first frame N and the 265th and subsequent scanning lines and the third and subsequent scanning lines in the second frame (N + 1) are also processed in the same manner. The correlation between the first and second frames can be accurately obtained.
[0053]
On the other hand, regarding the inter-field correlation, a value obtained by adding an offset value (for example, 16) to the absolute value of the difference between each field in the first frame is obtained for the Y signal, and this value is used as the first inter-field difference value. Then, a value obtained by adding an offset value (for example, 16) to the absolute value of the difference between the fields in the second frame is obtained, and this value is used as the difference value between the second fields.
[0054]
Since the inter-frame difference value is the sum of three absolute values as described above, the inter-frame difference value tends to be larger than the first and second field difference values when there is a moving image. . Therefore, it can be said that the inter-field correlation is used as a feature representing the vertical correlation in the case of a still image. Further, the offset value is set so that the inter-frame difference value does not exceed the first and second field difference values and the inter-frame correlation is determined to be high if the inter-frame difference value is slightly increased. belongs to. As a result, opportunities for correction by the correction unit 23 are increased, and crosstalk is reduced.
[0055]
Furthermore, since the Y signal that has been YC separated based on the intra-field line correlation by the YC separation unit 21 includes the C signal (there is crosstalk), in order to prevent a decrease in motion detection accuracy due to the crosstalk, FIG. For the sum of Y signals of neighboring 4 × 1 pixel blocks as shown in FIG. 5, the inter-frame difference value and the first and second inter-field difference values are obtained.
[0056]
Here, assuming that the NTSC video signal is NTSC, the red, green, and blue signals are R, G, B, and the color subcarrier frequency is fsc, the Y signal and the C signal are expressed by the following relational expression (1). Can be derived from.
[0057]
[Expression 1]

When demodulating the video signal NSTC, it is necessary to separate the IQ component from the C signal. In the NTSC system, the C signal is demodulated into an IQ component by sampling the C signal at a sampling frequency that is an integral multiple of the color subcarrier frequency fsc. A sampling frequency four times the color subcarrier frequency fsc is referred to as NTSC-4fsc. By sampling the C signal at the sampling frequency NTSC-4fsc, I, Q, -I, and -Q as shown in the following relational expression (2) can be demodulated.
[0058]
[Expression 2]

Therefore, crosstalk occurs in the Y signal and the C signal YC separated by the YC separation unit 21 based on the intra-field line correlation at a cycle depending on the sampling frequency. Therefore, the inter-frame difference value and the first and second field difference values are obtained for the sum of the Y signals of the neighboring 4 × 1 pixel blocks shown in FIG. 5 to reduce the influence of crosstalk.
[0059]
Next, a processing procedure for obtaining the inter-frame difference value and the first and second field difference values and detecting the motion of the image based on these difference values will be described with reference to the flowchart of FIG.
[0060]
First, as shown in FIG. 7, the target pixel block is extracted from the image, and the inter-frame difference value and the first and second field difference values are obtained for the sum of the Y signals of the target pixel block. As for the sum of the Y signals of the left and right pixel blocks, the inter-frame difference value and the first and second field difference values are obtained. Then, the sum of the inter-frame difference value of the pixel block of interest and the inter-frame difference value of each pixel block on the left and right is replaced and set as the inter-frame difference value of the pixel block of interest, and between the first and second fields of the pixel block of interest The sum of the difference value and the first and second field difference values of the left and right pixel blocks is replaced and set as the difference value between the first and second fields of the pixel block of interest (step S101). As a result, it is possible to reduce deterioration in motion detection accuracy of the isolated pixel block of interest.
[0061]
By comparing the inter-frame difference value of the pixel block of interest thus set and the first and second field difference values, it is determined whether or not the inter-frame difference value is larger than any of the first and second field difference values. Determination is made (step S102). If the inter-frame difference value is smaller than at least one of the first and second field difference values (“Yes” in step S102), the correlation between the frames is high. It is determined that there is (step S103). In addition, if the inter-frame difference value is larger than any of the first and second field difference values (“No” in step S102), the inter-field correlation (vertical correlation) is higher than the inter-frame correlation, so that the target pixel It is determined that the block is a moving pixel block (step S104).
[0062]
The processing in FIG. 6 is performed for every pixel block of the image, and it is determined whether each pixel block is a still pixel block or a moving pixel block.
[0063]
The scene change determination unit 24 determines whether there is a scene change between the frames according to the flowchart of FIG.
[0064]
First, the flag F is initialized to 0 (step S201), and it is determined whether or not half or more of the pixel blocks on the scanning line are moving pixel blocks (step S202). If more than half are moving pixel blocks (“Yes” in step S202), the scene is changed (step S203), and the flag F is updated to “a” (step S204). If more than half are not moving pixel blocks (“No” in step S202), it is assumed that there is no scene change (step S205), and the flag F is not updated.
[0065]
When the flag F = a, since there is almost no correlation between frames, the Y signal and C signal of the scanning line that is the object of determination are output as they are output from the YC separation unit 21. Further, when the flag F = 0, since there is an inter-frame correlation, the Y signal and C signal of the scanning line that is the object of determination are output to the correction unit 23.
[0066]
The processing of FIG. 8 is performed for every scanning line of the image. When there is a scene change, the Y signal and C signal of the scanning line are output as they are, and when there is no scene change, the Y of the scanning line is output. The signal and the C signal are output to the correction unit 23.
[0067]
When the correction unit 23 inputs the Y signal and C signal of the scanning line determined to have no scene change, the correction unit 23 sequentially processes each pixel block of the scanning line. For example, if the pixel block is determined to be a still pixel block by the motion detection unit 22, the average value of the Y signal and C signal of the pixel block in each successive frame is obtained and output. That is, the Y signal and C signal of the pixel block are corrected and output. If the pixel block is determined to be a moving pixel block by the motion detection unit 22, the Y signal and C signal of the pixel block are output as they are output from the YC separation unit 21.
[0068]
Next, a series of processing by the YC separation unit 12A will be described according to the flowchart of FIG.
[0069]
First, the composite color television signal is separated into a Y signal and a C signal by the YC separation unit 21 (step S301), and the motion of the image is moved using inter-field correlation and inter-frame correlation for each pixel block of one scanning line. Detection is performed by the detection unit 22 (step S302), and steps S301 and S302 are repeated until processing for one scanning line is completed (“Yes” in step S303), and thereafter, the process proceeds to processing by the scene change determination unit 24. (Step S304) With respect to one scanning line, it is determined whether or not there is a scene change between consecutive frames (Step S305). If there is no scene change for one scanning line (“No” in step S305), it is determined for each pixel block of one scanning line whether or not the pixel block is a moving pixel block (step S306). Is not a moving pixel block (“No” in step S306), the Y signal and C signal of the pixel block are corrected and output by the correction unit 23 (step S307), and if the pixel block is a moving pixel block (“Yes” in step S306), the Y signal and C signal of the pixel block separated by the YC separation unit 21 using the intra-field scanning line correlation are output as they are (step S308). If there is a scene change for one scanning line (“Yes” in step S305), the Y and C signals of the scanning line separated by the YC separation unit 21 using the intra-field scanning line correlation are output as they are. (Step S308).
[0070]
These steps S301 to S308 are repeated until the processing for all the scanning lines and all the pixel blocks of the image is completed (step S309).
[0071]
2 is obtained by omitting the steps S304 and S305 in the flowchart of FIG.
[0072]
As described above, in this embodiment, the composite color television signal is separated into the Y signal and the C signal by the YC separation unit 21, and the motion detection unit 22 detects the motion of the image using the inter-field correlation and the inter-frame correlation. Based on this image motion, the scene change determination unit 24 determines whether or not there is a scene change between frames. If there is no image motion and there is no scene change, the Y signal and the C signal are corrected by the correction unit 23. If the scene is changed or the image moves, the Y signal and the C signal separated by the YC separation unit 21 are outputted as they are, thereby improving the separation accuracy of the Y signal and the C signal. ing. In addition, a series of processing is possible only with the memory capacity for storing the video signals for two frames, and it is not necessary to increase the memory capacity.
[0073]
Similarly to the Y signal, motion detection can be performed by using the C signal, and the Y signal and the C signal may be corrected based on the motion detection result. Alternatively, motion detection may be performed using both the Y signal and the C signal, and the Y signal and the C signal may be corrected based on the motion detection result. Further, appropriate weighting or the like may be performed on each calculated value, or an average value of each value may be used instead of the sum of the values.
[0074]
FIG. 10 is a block diagram showing YC separation means in the second embodiment of the image processing apparatus of the present invention. The image processing apparatus according to the present embodiment applies the YC separation unit 12B of FIG. 10 instead of the YC separation unit 12 of FIG. 2 or the YC separation unit 12A of FIG.
[0075]
In the YC separation unit 12B of the present embodiment, a first motion detection unit 31 and a second motion detection unit 32 are inserted before and after the scene change determination unit 24 instead of the motion detection unit 22 of FIG.
[0076]
The YC separation unit 21 separates the composite color television signal into a Y signal and a C signal by performing a YC separation process using intra-field scanning line correlation (vertical correlation) on the composite color television signal.
[0077]
The first motion detection unit 31 delays the Y signal separated by the YC separation unit 21 by one frame, and uses the delayed Y signal for one frame and the Y signal for the next one frame following the frame. Thus, the inter-frame correlation for the Y signal is obtained, and the motion of the image is detected based on the inter-frame correlation.
[0078]
Here, for the Y signal, the absolute value of the difference between the even field in the first frame and the even field in the second frame, the absolute value of the difference between the odd field in the first frame and the odd field in the second frame, and the The absolute value of the difference between the sum of the odd field in the even field and the second frame and the sum of the odd field in the first frame and the even field in the second frame is obtained, and the sum of the absolute values is further obtained. It is used as an inter-frame difference value indicating inter-frame correlation, and image motion is detected based on the inter-frame difference value.
[0079]
A more specific process of the first motion detection unit 31 will be described with reference to the flowchart of FIG.
[0080]
First, a 4 × 1 pixel block of interest is extracted, an inter-frame difference value is obtained for the Y signal sum of the pixel block of interest, and the Y signal sum of the left and right pixel blocks of the pixel block of interest is also calculated. The inter-frame difference value is obtained. Then, the sum of the inter-frame difference value of the target pixel block and the inter-frame difference value of the left and right pixel blocks is set as the inter-frame difference value of the target pixel block (step S401).
[0081]
Next, the inter-frame difference value of the pixel block of interest is compared with a preset threshold value (eg, 48) to determine whether the inter-frame difference value is smaller than the threshold value (step S402). If the inter-frame difference value is smaller than the threshold (“Yes” in step S402), since the correlation between the frames is high, it is determined that the pixel block of interest is a still pixel block (step S403). If the inter-frame difference value is not smaller than the threshold value (“No” in step S402), since the correlation between the frames is low, it is determined that the pixel block of interest is a moving pixel block (step S404).
[0082]
The processing in FIG. 11 is performed for every pixel block of the image, and it is determined whether each pixel block is a still pixel block or a moving pixel block.
[0083]
The scene change determination unit 24 determines whether or not half or more of the pixel blocks of the scanning line are moving pixel blocks based on the detection result of the first motion detection unit 31. If more than half of them are moving pixel blocks, there is a change in the scene and there is almost no correlation between frames, so that the Y signal and C signal of the scanning line subjected to determination are output from the YC separation unit 21 Output as is. If more than half are not moving pixel blocks, there is no scene change and there is a correlation between frames, so the Y signal and C signal of the scanning line are output to the second motion detector 32.
[0084]
The second motion detection unit 32 uses the Y signals for two consecutive frames separated by the YC separation unit 21 to obtain an inter-field correlation, and the inter-field correlation and the frame obtained by the first motion detection unit 31. Based on the inter-correlation, motion is detected for each pixel block.
[0085]
Regarding the inter-field correlation, a value obtained by adding an offset value (for example, 16) to the absolute value of the difference between each field in the first frame is obtained for the Y signal, and this value is used as the first inter-field difference value. A value obtained by adding an offset value (for example, 16) to the absolute value of the difference between the fields in the two frames is obtained, and this value is used as the second inter-field difference value.
[0086]
Here, the target pixel block is extracted from the image, the difference value between the first and second fields is obtained for the sum of the Y signals of the target pixel block, and the Y signal of each pixel block on the left and right of the target pixel block is obtained. Also for the sum, a difference value between the first and second fields is obtained. Then, the sum of the first and second field difference values of the pixel block of interest and the first and second field difference values of the left and right pixel blocks is used as the first and second field difference values of the pixel block of interest. Replace and set.
[0087]
Then, the inter-frame difference value of the target pixel block obtained by the first motion detection unit 31 is compared with the first and second inter-field difference values of the target pixel block, and the inter-frame difference value is the first and second inter-frame difference values. If it is smaller than at least one of the inter-field difference values, the correlation between the frames is high, so that the target pixel block is determined to be a still pixel block. Further, if the inter-frame difference value is larger than both the first and second inter-field difference values, the inter-field correlation (vertical correlation) is higher than the inter-frame correlation, so that the target pixel block is a moving pixel block. judge.
[0088]
Such processing is performed for every pixel block of the image, and it is determined whether each pixel block is a still pixel block or a moving pixel block.
[0089]
If the pixel block is determined to be a stationary pixel block by the second motion detection unit 32, the correction unit 23 calculates and outputs the average value of the Y signal and C signal of the pixel block in each successive frame. That is, the Y signal and C signal of the pixel block are corrected and output. If the second motion detection unit 32 determines that the pixel block is a moving pixel block, the Y signal and C signal of the pixel block are output as they are output from the YC separation unit 21.
[0090]
Next, a series of processing by the YC separation unit 12B will be described according to the flowchart of FIG.
[0091]
First, the composite color television signal is separated into a Y signal and a C signal by the YC separation unit 21 (step S501), and the first motion detection unit uses the inter-frame correlation for each pixel block of one scanning line. 31 (step S502), until the process for one scanning line is completed (“Yes” in step S503), steps S501 and S502 are repeated, and thereafter, the process proceeds to the process by the scene change determination unit 24 ( Step S504) It is determined whether or not there is a scene change between consecutive frames for one scanning line (step S505). If there is no scene change for one scanning line (“No” in step S505), the second motion detection unit 32 uses the inter-field correlation and the inter-frame correlation for each pixel block of the one scanning line. If it is detected (step S506) and is not a moving pixel block (“No” in step S507), the Y signal and C signal of the pixel block are corrected and output by the correction unit 23 (step S508). If so (“Yes” in step S507), the Y and C signals of the pixel block separated by the YC separation unit 21 using the intra-field scanning line correlation are output as they are (step S509). If there is a scene change for one scanning line (“Yes” in step S505), the Y and C signals of the scanning line separated by the YC separation unit 21 using the intra-field scanning line correlation are output as they are. (Step 509).
[0092]
These steps S501 to S509 are repeated until the processing for all the scanning lines and all the pixel blocks of the image is completed (step S510).
[0093]
As described above, in the present embodiment, the composite color television signal is separated into the Y signal and the C signal, and the motion of the image is detected by the first motion detection unit 31 using the inter-frame correlation, and based on the motion of the image. It is determined whether there is a scene change between frames. If there is a scene change, the Y signal and C signal separated by the YC separation unit 21 are output as they are. If there is no scene change, the image motion is detected again by the second motion detector 32 using inter-field correlation and inter-frame correlation. If there is image motion, the Y signal separated by the YC separator 21 is detected. The C signal and the C signal are output as they are, and if there is no movement of the image, the Y signal and the C signal are corrected and output by the correction unit 23, thereby improving the separation accuracy of the Y signal and the C signal.
[0094]
Therefore, the motion detection by the first motion detection unit 31 is always performed, and the motion detection by the second motion detection unit 32 is performed only when there is no scene change. Thereby, a series of motion detection processing speed can be improved. Furthermore, since the correction by the correction unit 23 is performed only when there is no scene change and no image motion, this correction process can be simplified.
[0095]
In addition, a series of processing is possible only with the memory capacity for storing the video signals for two frames, and it is not necessary to increase the memory capacity.
[0096]
Similarly to the Y signal, motion detection can be performed by using the C signal, and the Y signal and the C signal may be corrected based on the motion detection result. Alternatively, motion detection may be performed using both the Y signal and the C signal, and the Y signal and the C signal may be corrected based on the motion detection result. Further, appropriate weighting or the like may be performed on each calculated value, or an average value of each value may be used instead of the sum of the values.
[0097]
In addition, the present invention is achieved by executing a program for realizing the image processing method by hardware such as a CPU or a computer. Therefore, the present invention includes not only an image processing apparatus but also an image processing method, a program for executing the method, and a recording medium storing the program. The present invention also includes an image forming apparatus to which the image processing apparatus is applied. Examples of the image forming apparatus include a CRT, a liquid crystal display, and a printer.
[0098]
The program is recorded on a recording medium such as a magnetic disk, an optical disk, or a hard disk built in a computer, or transmitted and received through a communication network. A terminal device or the like with a computer or a microprocessor can implement the present invention by reading a program from a recording medium or receiving the program through a communication network such as the Internet and executing the program. When the program is received through a communication network such as the Internet, a download program is required. The download program is also recorded on a recording medium such as a magnetic disk, an optical disk, or a hard disk built in the computer, or transmitted and received through a communication network. Also, these programs can be periodically downloaded to the terminal device via the Internet.
[0099]
Furthermore, in a system including a terminal device such as a computer and a network, a plurality of processes can be distributed to the terminal devices such as a computer. Therefore, the program can be applied not only to a single terminal device such as a computer but also to a system. In this system, a television, a video camera, a personal computer, a CRT, a liquid crystal display, a printer, a server, and the like are connected through a network. Examples of the network include the Internet and a LAN.
[0100]
Examples of the recording medium include semiconductor storage elements such as mask ROM, EPROM, EEPROM, and flash ROM, IC cards, hard disks, flexible disks, optical disks such as MO, CD, MD, and DVD, and magnetic tapes. Other types of recording media may be used as long as they can be recorded.
[0101]
【The invention's effect】
As described above, according to the present invention, a composite color television signal is separated into a luminance component signal and a color component signal, and at least two frames of the separated luminance component signal and color component signal are used. If the image motion is detected and there is no image motion, the luminance component signal and the color component signal are corrected and output. If there is an image motion, the Y signal and the C signal are output as they are, and thereby the luminance component signal is output. The separation accuracy of the signal and the color component signal is improved. In addition, a series of processing is possible only with the memory capacity for storing the video signals for two frames, and it is not necessary to increase the memory capacity.
[0102]
In addition, since the correlation is obtained for each pixel block, it is possible to simplify the arithmetic processing and reduce the influence of crosstalk. Alternatively, since the correlation of the pixel block of interest is set with reference to the correlation of other pixel blocks adjacent to the pixel block of interest, it is possible to reduce the deterioration of the motion detection accuracy of the isolated pixel block of interest.
[0103]
Furthermore, when it is determined that there is a scene change, the luminance component signal and the color component signal are output as they are without passing through the correction unit, so that the processing of the correction unit can be reduced and the processing speed is improved. . Alternatively, since the correction process is performed only when there is no scene change and no image motion, this correction process can be simplified. Further, since it is determined whether or not there is a scene change in the scanning line according to the ratio of the moving pixel block included in each pixel block on the scanning line, this determination can be easily performed, and the determination process Is simplified.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a first embodiment of an image processing apparatus according to the present invention.
2 is a block diagram showing a configuration of YC separation means in the image processing apparatus of FIG. 1. FIG.
3 is a block diagram showing another example of the configuration of YC separation means in the image processing apparatus of FIG. 1;
FIG. 4 is a diagram illustrating a correlation between first and second frames for a color component signal.
FIG. 5 is a diagram schematically showing a neighboring 4 × 1 pixel block.
6 is a flowchart showing a processing procedure for motion detection by a motion detection unit in the YC separation unit of FIGS. 2 and 3. FIG.
FIG. 7 is a diagram illustrating a target pixel block and other pixel blocks adjacent to the target pixel block.
FIG. 8 is a flowchart showing a processing procedure for scene change determination by a scene change determination unit in the YC separation unit of FIG. 3;
9 is a flowchart showing a processing procedure for composite color television signal separation by the YC separation means of FIG. 3;
FIG. 10 is a block diagram showing YC separation means in the second embodiment of the image processing apparatus of the present invention.
11 is a flowchart showing a processing procedure by a first motion detection unit in the YC separation unit of FIG.
12 is a flowchart showing a processing procedure for composite color television signal separation by the YC separation means of FIG. 10; FIG.
[Explanation of symbols]
10 Image processing device
11 Input means
12, 12A, 12B YC separation means
13 Color difference demodulation means
14 Filter processing means
15 Resolution conversion processing means
16 color conversion means
17 Halftone means
18 Printer section
21 YC separator
22 Motion detector
23 Correction part
24 Scene change determination unit
31 1st motion detection part
32 Second motion detector

Claims (15)

In an image processing apparatus comprising YC separation processing means for inputting a composite color television signal representing an image and separating the composite color television signal into a luminance component signal and a color component signal,
YC separation processing means
A YC separation unit for separating a composite color television signal into a luminance component signal and a color component signal using intra-field scanning line correlation;
A motion detection unit that detects a motion of an image using two frames of at least one of the separated luminance component signal and color component signal;
Based on the detected movement of the image, it is determined whether or not to perform the correction process of the luminance component signal or the color component signal. If it is determined that the correction process is to be performed, the luminance component signal and the color component signal are corrected. And a correction unit that outputs the luminance component signal and the color component signal as they are when it is determined that the correction processing is not performed. The motion detection unit, for at least one of the luminance component signal and the color component signal, sums the even field in the first frame and the odd field in the second frame and the sum of the odd field in the first frame and the even field in the second frame. And the absolute value of the difference between the even field in the first frame and the even field in the second frame, and the absolute value of the difference between the odd field in the first frame and the odd field in the second frame. The image processing apparatus according to claim 1, wherein an image motion is detected using an absolute value as a correlation between frames. The motion detection unit obtains the sum or average value of the pixel blocks for each pixel block composed of a plurality of pixels for at least one of the luminance component signal and the color component signal, and uses the sum or average value of the pixel blocks to The image processing apparatus according to claim 2, wherein an inter-frame correlation is obtained for each block. The motion detection unit obtains the sum or average value of the inter-frame correlation of the pixel block of interest and the inter-frame correlation of other pixel blocks adjacent to the pixel block of interest, and uses this sum or average value as the inter-frame correlation of the pixel block of interest. The image processing apparatus according to claim 3, wherein the image processing apparatus is replaced. The motion detection unit obtains an absolute value of a difference between each field in the frame for at least one of the luminance component signal and the color component signal, and detects the motion of the image using the absolute value as a correlation between fields. The image processing apparatus according to claim 1, wherein: The motion detection unit obtains the sum or average value of the pixel blocks for each pixel block composed of a plurality of pixels for at least one of the luminance component signal and the color component signal, and uses the sum or average value of the pixel blocks to The image processing apparatus according to claim 2, wherein an inter-field correlation is obtained for each block. The motion detection unit obtains the sum or average value of the inter-field correlation of the target pixel block and the inter-field correlation of other pixel blocks adjacent to the target pixel block, and uses this sum or average value as the inter-field correlation of the target pixel block. The image processing apparatus according to claim 6, wherein the image processing apparatus is replaced. A scene change determination unit that determines whether there is a change in the scene of the image based on the movement of the image detected by the motion detection unit;
When the scene change determination unit determines that there is a scene change, the luminance component signal and the color component signal are output as they are without the correction unit, and when the scene change determination unit determines that there is no scene change, The image processing apparatus according to claim 1, wherein the luminance component signal and the color component signal are output via a correction unit. The motion detection unit obtains the sum or average value of the pixel blocks for each pixel block composed of a plurality of pixels for at least one of the luminance component signal and the color component signal, and uses the sum or average value of the pixel blocks to Determine whether the block is a static pixel block or a moving pixel block,
The scene change determination unit is configured to determine, for each scanning line of an image, whether there is a scene change in the scanning line according to a ratio of moving pixel blocks included in each pixel block on the scanning line. The image processing apparatus according to claim 8. In an image processing apparatus comprising YC separation processing means for inputting a composite color television signal representing an image and separating the composite color television signal into a luminance component signal and a color component signal,
YC separation processing means
A YC separation unit for separating a composite color television signal into a luminance component signal and a color component signal using intra-field scanning line correlation;
A first motion detection unit for obtaining an inter-frame correlation for at least one of the separated luminance component signal and color component signal, and detecting a motion of the image using the inter-frame correlation;
A scene change determination unit that determines whether there is a change in the scene of the image based on the motion of the image detected by the first motion detection unit;
A second inter-field correlation is obtained for at least one of the separated luminance component signal and color component signal, and the motion of the image is detected using the inter-field correlation and the inter-frame correlation obtained by the first motion detector. A motion detector,
Based on the motion of the image detected by the second motion detection unit, it is determined whether or not to perform correction processing of the luminance component signal or the color component signal. When the component signal is corrected and then output, and when it is determined not to perform the correction process, a correction unit that outputs the luminance component signal and the color component signal as they are,
When the scene change determination unit determines that there is a scene change, the luminance component signal and the color component signal are output as they are without the correction unit, and when the scene change determination unit determines that there is no scene change, An image processing apparatus that outputs a luminance component signal and a color component signal via a correction unit. An image forming apparatus comprising the image processing apparatus according to claim 1. In an image processing method for inputting a composite color television signal representing an image and separating the composite color television signal into a luminance component signal and a color component signal,
A YC separation step of separating the composite color television signal into a luminance component signal and a color component signal using intra-field scanline correlation;
A motion detection step of detecting a motion of an image using two frames of at least one of the separated luminance component signal and color component signal;
Based on the detected movement of the image, it is determined whether or not to perform the correction process of the luminance component signal or the color component signal. If it is determined that the correction process is to be performed, the luminance component signal and the color component signal are corrected. And a correction step of outputting the luminance component signal and the color component signal as they are when it is determined that the correction processing is not performed. In an image processing method for inputting a composite color television signal representing an image and separating the composite color television signal into a luminance component signal and a color component signal,
A YC separation step of separating the composite color television signal into a luminance component signal and a color component signal using intra-field scanline correlation;
A first motion detection step of obtaining an inter-frame correlation for at least one of the separated luminance component signal and color component signal and detecting a motion of the image using the inter-frame correlation;
A scene change determination step for determining whether there is a change in the scene of the image based on the motion of the image detected in the first motion detection step;
A second inter-field correlation is obtained for at least one of the separated luminance component signal and color component signal, and a motion of the image is detected using the inter-field correlation and the inter-frame correlation obtained in the first motion detection step. A motion detection step;
Based on the motion of the image detected in the second motion detection step, it is determined whether or not to correct the luminance component signal or the color component signal. If it is determined that the correction processing is to be performed, the luminance component signal and the color When it is determined that the component signal is corrected and then output, and the correction process is not performed, the luminance component signal and the color component signal are output as they are,
When it is determined that there is a scene change in the scene change determination step, the luminance component signal and the color component signal are output as they are without being processed in the correction step, and when it is determined that there is no scene change in the scene change determination step An image processing method comprising: outputting a luminance component signal and a color component signal after processing in a correction step. A program for realizing the image processing method according to claim 12 or 13. A recording medium storing the program according to claim 14.

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