JP2004215069A - Retention preview method and apparatus, and compressibility prediction method in lossy compression - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To regulate a quality (compression) parameter at very high speed while previewing a picture quality and a compression size before retention. <P>SOLUTION: In the retention preview method for retaining an image in a Lossy compression form and displaying the image, only a partial area predetermined or designated by a user in an original image storage part (a) is segmented by a segmentation control part (b), a segmented image of a display portion is stored in a storage part (c), and a sampling segmentation image is stored in a storage part (d). Only a portion of a displayed image is then compressed and extended by a compression/extension control part (g), the compressed and extended image is displayed on a screen by a display control part (k), and the compression size of an entire image is estimated based upon the compression size of only a portion of the image displayed by the segmentation control part (b). The estimated compression size is simultaneously displayed on the display screen to confirm the picture quality and compressibility. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

となり、サンプリングしない場合にくらべて、０．００４＝０．４％しか違いがなく、本処理で処理性能を低下させることなく、より精度の高い圧縮サイズを予測することが可能であることがわかる。
【００２７】
（３）サンプリング結果のキャッシュ（請求項３に対応）
圧縮パラメータを変更することなく、ユーザーが表示部分のスクロールまたは表示倍率の変更などを行う場合において、前述（２）のサンプリング画像を表示画像として採用する、また一度表示およびサンプリング用に処理された圧縮／伸張データは破棄せずに保持しておくことにより、効率化を図る。そのために切出し表示画像記憶部ｃ、圧縮データ格納部ｉおよび伸張画像記憶部ｊは、表示部分の画像を８＊８ｐｉｘｅｌに分割した状態で管理する。切出し制御部ｂは、表示画像を８＊８ｐｉｘｅｌ単位に分割して切出す。圧縮・伸張処理は、分割領域単位で行われ、伸張画像記憶部ｊにそれぞれ保管される。表示制御部ｋは、これら分割処理された画像を領域単位で表示出力処理する。
【００２８】
例えば、スクロール操作された場合を考える。通常ならば、スクロールにより生じた新たな表示位置にあわせて、表示領域すべてを切出し・圧縮・伸張をすべて行う必要がある。しかし、既にサンプリング画像が存在する場合には、領域すべてを処理する必要がなく、存在しない画素のみを新たに切出し・圧縮・伸張処理する。サンプリング画像が存在する場合には、サンプリング画像の圧縮データ格納部ｈより伸張処理部ｇ−２を経由して、伸張画像記憶部ｊに伸張画像が準備され、表示画像として利用される。圧縮データ格納部ｈ，ｉまたは伸張画像記憶部ｊのデータを保持することにより、スクロール・倍率変更などにより表示領域が変更されたとしても、再処理することなく、高速に効率よく表示プレビューが行える。また、圧縮データが蓄積されることにより、次第に予想圧縮サイズも精度を高めていくことになる。
【００２９】
（４）画質劣化が大きい／小さい場所を自動的に表示（請求項４に対応）
圧縮の一般的な傾向として、複雑なデータ（画像）は圧縮率が低く、単純なデータ（画像）は圧縮率が高くなる。ＪＰＥＧ圧縮では、人間が感知しにくい高周波成分をカットすることにより、高い圧縮率を得るという特徴をもち、この高周波成分のカットが画質の劣化となって表れる。したがって、複雑なデータほど変化が激しく、高周波成分が多く、画質の劣化も多くなる傾向にある。そこで、圧縮率の低い物ほど画質の劣化が激しいと予測することができる。
また、サンプリング圧縮データを伸張して、元画像と画素単位の差分を求めることにより、画質劣化の度合いを直接求めることもできる。
【００３０】
品質差分値（％）＝Σ（元画像の画素値−伸張画素の値）＊１００／（画素数＊画素ＭＡＸ値）
０ならば画質劣化なし、値が大きいほど劣化が激しい
前述（２）の処理において、サンプリングされた圧縮データから、最も圧縮率が低くなる位置、高くなる位置を検出する。または、品質差分値が最も大きくなる位置、小さくなる位置を検出する。それらの検出された位置を自動的に表示することにより、ユーザーが画質（圧縮）パラメータを設定する際に、効率よい作業が行えるようにする。
【００３１】
図３，６，８、９が、その実施例を示す画面図である。
最初に、図３に示すように画像左上端が表示されていた場合、サンプリング圧縮データより最も画質劣化が激しいと判断され自動表示されたのが、図６である。
より詳細に画質調整を行なうためには、図８および図９に示すように、最も画質劣化が激しいと判断された部分を自動的に拡大表示して画質を調整する画面が示されている。
自動表示方法の一つとして、上記判定方法により想定される画質が最も悪いと思われる部分、最も良いと思われる部分を両方同時に表示することにより、ユーザーはそのバランスを見ながら画質決定できる方法もある。
【００３２】
（５）正確な圧縮サイズ（請求項５に対応）
本発明の請求項２に対応する実施例において、サンプリング数を増やすことや、請求項３に対応する実施例において、画像全体をスクロール表示させることにより、より正確な圧縮サイズを推定できるようになるが、次のような場合には請求項１の方法とは別に画像全体を圧縮処理する方法が有効である。
【００３３】
・元画像サイズが小さく、画像全体の圧縮処理時間が少ないもの（画面サイズと比べて大幅に大きくないもの）、
・全体の処理を簡素化したい場合（請求項２，３の方法を使用しない場合）、
・マルチタスク処理が可能なＣＰＵの空時間を有効活用できるシステムで、ユーザー操作待ちなどＣＰＵの空時間が多いと予測される場合、
・正確な圧縮サイズが必要になる場合（例えば、１．４４ＭＢのフレキシブルディスクに収めようとした場合に、入りきるかどうかを検証したい場合）。
【００３４】
このような場合には、バックグラウンドで自動的に、もしくはユーザー操作により、画像全体を圧縮し、正確な圧縮サイズを得る。また、この状態（現状の圧縮パラメータ）でファイル保存が指定された場合は、圧縮処理することなく、既に生成されている圧縮データをそのままファイルに書き出すことにより処理時間の短縮ができる。
【００３５】
（６）精度の高い圧縮サイズの推測（請求項６に対応）
図１０は、ＪＰＥＧ圧縮における圧縮パラメータと圧縮サイズの関係を示す図である。また、図１１〜図１９は、圧縮パラメータと圧縮サイズの関係を示す特性曲線図である。
圧縮パラメータｑＦａｃｔｏｒは、ＪＰＥＧ圧縮における量子化テーブルを定める値であり、ｑＦａｃｔｏｒ＝１００で標準的な量子化テーブルとなる。各図における全体とは、画像全体を圧縮したものを表わす。領域Ａ，Ｂは、その中の一部領域のみを抜き出して圧縮した結果を表わす。
【００３６】
すなわち、領域Ａ，Ｂは、請求項１における表示部分のみを抜き出して圧縮したものと同じ状態を表す。サブサンプリングは、横方向および縦方向の輝度成分、色差成分のサブサンプリング比を表す。２＊２は明暗の情報と色の情報を同じ１／２ずつにした場合、４＊２は、それぞれ１／４と１／２にした場合である。
明暗は人間の目に敏感であり、色は人間の目に鈍感であるため、明暗の情報は１／２、色の情報を１／４にしている。
図１１，図１２のグラフは、全体と全体（４＊２）との比較および領域Ａ，Ｂとの比較を示す図である。図１１，図１２より、画像全体または画像の一部にかかわらず、およびサブサンプリングなどの要因にもかかわらず、どの場合も同じ傾向になることがわかる。
【００３７】
図１３のグラフは、横軸に画像全体を圧縮したサイズ、縦軸に領域Ａ，Ｂのみを圧縮したサイズをとってグラフ３にしたものである。図１３のグラフ３より、両者は比例関係にあることがわかり、２点の座標がわかれば近似直線式を求めることができる。
さらに厳密に近似すると、ｑＦａｃｔｏｒ＝１００（標準値）を境として、多少直線の傾きが変化している。これを図１４、図１５のグラフ４，５に示す。グラフ４，５では、Ｒ２乗値＝０．９９８７〜０．９９９９とかなり精度の良い近似式が得られることがわかる（Ｒ２乗値とは近似合のばらつき度合いを表す。１の場合ばらつきなしとなり、０に近づくにつれてばらつきが大きくなり近似の精度が悪くなることを表す）。この傾向は、サブサンプリング比＝４：２になっても変わらず。図１７および図１８のグラフ７．８でも、Ｒ２乗値＝０．９９９５〜１．００００となり、ほぼ完全に近似できることがわかる。
【００３８】
したがって、画像全体および表示部分の圧縮サイズを、ｑＦａｃｔｏｒ＝１００をはさんで合計３箇所測定することができれば、後は表示部分の圧縮サイズから全体画像の圧縮サイズを予測できるようになる。
また、図１９におけるグラフ９に示すように、領域ごとの圧縮データも同様に直線近似の関係になる。したがって、請求項２，３の処理において、サンプリングされた領域からおおよその全体圧縮サイズを、同様にｑＦａｃｔｏｒ＝１００をはさんで合計３箇所測定することができれば、後は表示部分の圧縮サイズからおおよその全体圧縮サイズを予測できるようになる。
【００３９】
（７）撮影後の画質調整（請求項７に対応）
デジタルスチルカメラなど撮影直後に圧縮および保存する機器において、品質（圧縮）パラメータはあらかじめ設定しておいた値で撮影、圧縮および保存される。また、通常は、残り撮影枚数を確実に制御するために、どの画像でも同じ圧縮サイズになるまで圧縮リトライ処理し、適切な品質パラメータを探し出してようやく保存されるため処理の無駄も発生している。
【００４０】
しかし、本発明を適用することにより、ユーザーは撮影後に画質と残り撮影枚数を確認しながら、最適な圧縮パラメータで保存できる。
図２０に、デジタルカメラ画面の実施例を示す。図２０は、撮影後に請求項４の方法に基づき、最も画質が悪いと思われる部分を拡大表示した状態である。
図２０の画面では、画質はよいが圧縮サイズが大きくなりすぎるため、残り撮影枚数が１枚になってしまう。
【００４１】
そこで、図２１に示すように、圧縮パラメータを下げると残り撮影可能枚数は１０枚まで増やすことができるが、これでは画質が悪すぎる。そこで、図２２に示すように、圧縮パラメータを多少上げ、画質をほどほどに確保しつつ残り撮影枚数８枚を確保した。このように、ユーザーの意思により、画質や残り撮影枚数を調整しながら、品質（圧縮）パラメータを設定できるようになる。通常、どの画像も同じ圧縮サイズにするということは、緻密な画像ほど品質パラメータを下げ、画質が悪くなり、緻密でない画像は品質パラメータを上げ、画質が良いという矛盾した傾向になりがちであるが、ユーザーが画質をみながら調整できるようにすることにより、ユーザーの目的にあった撮影、圧縮および保存が可能になる。
【００４２】
（８）簡易表示モード（請求項８に対応）
前記請求項１の方法では、表示対象領域を切り出して圧縮処理するため、画像全体が表示されるような全体表示モードなど縮小倍率が大きい場合には、結局画像全体または画像の大部分を圧縮処理することになり、処理の効率化、高速化が図れないことになる。また、ＪＰＥＧなどのＬｏｓｓｙ圧縮における画像劣化に伴うノイズなどは微細なものが多く、縮小表示では、その画質をチェックすることはできない。そこで本実施例の方法では、縮小表示されている場合は、その縮小画像を作成し、縮小画像を圧縮および伸張したものを１００％で表示させる。
これにより、本来の画質を正確に表現することにはならないが、少ない処理で高速に画質調整の指標となる画像を表示することができるようになる。
【００４３】
（９）比較表示、品質差分値（請求項９に対応）
図２３は、本発明の請求項９に対応する実施例の図である。
図２３では、画質調整がより適切に行えるように、本発明の方法を用いて元画像とＪＰＥＧ圧縮画像を比較表示させている。また、客観的な評価もできるように、品質差分値として画質劣化の度合いを数値で表示する。品質差分値とは、次の式で求められる。０の場合、差分なし＝画質の劣化なしとなる。
品質差分値（％）＝Σ（元画像の各画素値−ＪＰＥＧ圧縮画像の各画素値）＊１００／（画素数＊画素ＭＡＸ値）
【００４４】
（１０）一部領域のプレビュー（請求項１０に対応）
図２４は、本発明の請求項１０に対応する実施例の図である。
一部領域のみを選択し、請求項１の方法により圧縮および伸張した結果を表示させている。画像全体の中で必要な部分のみをＪＰＥＧ保存でき、そのときの画質をプレビューしながら品質（圧縮）パラメータを調整できる。
【００４５】
（１１）その他の実施例（請求項１１，１２に対応）
なお、本発明の他の実施例としては、プレビューしないで、単に本発明の処理を用いて圧縮サイズ（率）の予測のみを行う方法がある。
また、画質を変更しないで、トリミング、リサイズ等によりデータ自体を縮小しながら、画像および残容量をプレビューする方法も本発明に含まれる。
【００４６】
【発明の効果】
以上説明したように、本発明によれば、以下のような効果を奏する。
（ａ）請求項１に対応する実施例では、Ｌｏｓｓｙ圧縮により発生する画質劣化の状態を高速にプレビューできる。例えば、Ａ３−４００ｄｐｉ（データサイズ約９２ＭＢ）など大容量の画像でも、表示サイズ分の処理量ですむため、処理が高速である。プレビューと同時に圧縮保存した場合のおおよそのデータサイズを知ることができる。
【００４７】
（ｂ）請求項２に対応する実施例では、上記（ａ）の作用効果において、プレビューと同時に知ることができる圧縮データサイズの誤差精度を処理速度を低下させることなく向上させることができる。
（ｃ）請求項３に対応する実施例では、表示スクロールまたは表示倍率変更するたびに細切れの圧縮データがキャッシュされていくため、次第に処理速度が向上するとともに、圧縮データサイズの誤差精度が向上していく。
【００４８】
（ｄ）請求項４に対応する実施例では、Ｌｏｓｓｙ圧縮による画質劣化が最も激しいと思われる部分、または画質劣化が最も少ないと思われる部分を、自動的に表示あるいは拡大表示することにより、ユーザーの画質判定および圧縮パラメータの設定をより効率的に補助することができる。
（ｅ）請求項５に対応する実施例では、正確な圧縮サイズを求めるために画像全体を圧縮処理した場合は、再度圧縮処理することなく、（つまり、待ち時間なく）データ保存できる。
【００４９】
（ｆ）請求項６に対応する実施例では、正確な圧縮データサイズを毎回複雑な処理をしなくても、簡単に算出できるようになる。
（ｇ）請求項７に対応する実施例では、デジタルカメラなどの撮影後直接Ｌｏｓｓｙ圧縮される入力装置において、ユーザーは撮影後に画質と残り撮影可能枚数を照らし合わせながら、品質（圧縮）パラメータを指定できる。
【００５０】
（ｈ）請求項８に対応する実施例では、簡易モードにより、正確な画質ではないが、高速な処理速度を保持しながら、圧縮パラメータ設定の尺度を得ることが可能となる。ＪＰＥＧ圧縮における画質劣化はモスキートノイズやブロックノイズなど微細なノイズであるため、縮小表示では請求項１の方法で確認できないが、簡易モード（本発明）では確認できるようになる。
【００５１】
（ｉ）請求項９に対応する実施例では、比較表示により、画質劣化の状況をユーザーは視覚的に確認でき、また品質差分値により劣化量を定量的に知ることができるため、効率よく圧縮パラメータを設定することが可能になる。
（ｊ）請求項１０に対応する実施例では、画像の一部領域のみを保存する場合、またはパンフレット画像の写真部分・グラフ図形部分、文字部分など領域ごとに異なる特性に合わせて、圧縮率・画質を変更させて保存する場合などにおいて、領域ごとのプレビューが可能になる。
【図面の簡単な説明】
【図１】本発明の一実施例を示す圧縮伸張処理システムの全体構成図である。
【図２】図１における各処理部の詳細配置図である。
【図３】本発明の一実施例を示すＪＰＥＧ保存プレビュー画面の図である。
【図４】圧縮サイズは小さいが、画質が悪い場合の画面図である。
【図５】画質と、圧縮サイズのバランスを調整した画面図である。
【図６】圧縮率の悪い領域を自動表示する画面図である。
【図７】同じ圧縮パラメータで異なる領域の圧縮サイズを比較した場合の画面図である。
【図８】画質が悪い部分を自動拡大表示した画面図である。
【図９】自動拡大表示後に画質調整した画面図である。
【図１０】ＪＰＥＧ圧縮サイズの関係を示す図である。
【図１１】圧縮パラメータと圧縮サイズの関係（全体画像）を示すグラフ１である。
【図１２】圧縮パラメータと圧縮サイズの関係（領域）を示すグラフ２である。
【図１３】全体圧縮サイズと領域圧縮サイズの関係を示すグラフ３である。
【図１４】全体と領域圧縮サイズの関係を示すグラフ４である。
【図１５】全体と領域圧縮サイズの関係を示すグラフ５である。
【図１６】圧縮サイズの関係を示すグラフ６である。
【図１７】圧縮サイズの関係を示すグラフ７である。
【図１８】圧縮サイズの関係を示すグラフ８である。
【図１９】領域圧縮サイズ同士の関係を示すグラフ９である。
【図２０】本発明におけるデジタルカメラ画面の例を示す図である。
【図２１】本発明におけるデジタルカメラ画面の例（残り枚数多いが、画質悪い）を示す図である。
【図２２】同じくデジタルカメラ画面の例（残り枚数の確保をしながら画質向上）を示す図である。
【図２３】本発明における比較表示および差分値の表示例を示す図である。
【図２４】本発明における一部領域のみの品質プレビュー例を示す図である。
【符号の説明】
ａ…元画像記憶部、ｂ…切出し制御部、ｃ…表示部分の切出し画像記憶部、
ｄ…サンプリング切出し画像記憶部、ｅ…入力制御部、ｆ…主制御部、
ｇ…圧縮／伸張制御部、ｈ…サンプリング画像の圧縮データ格納部、
ｉ…表示画像の圧縮データ格納部、ｊ…伸張画像記憶部、ｋ…表示制御部、
ｌ…入出力装置、ｂ−１…表示サイズ倍率取得部、
ｂ−２…切出し位置演算部、ｂ−３…切出し処理部、
ｅ−１…スクロール＆倍率操作検知部、ｅ−２…圧縮パラメータ入力検知部、
ｇ−１…圧縮処理部、ｇ−２…伸張処理部、
ｇ−３…圧縮サイズ（率）取得部、ｋ−１…表示位置検出部、
ｋ−２…変倍処理部、ｋ−３…描画制御部、Ａ…全体画像ビュー、
Ｂ…メインビュー、Ｃ…現在表示されている領域、
Ｄ…圧縮パラメータ指定コントロール、Ｅ…予想サイズ＆圧縮率の表示領域、
Ｆ…正確なサイズ算出ボタン、Ｇ…確定ボタン、
Ｈ…表示倍率変更コントロール、Ｉ…メインビュー、Ｊ…圧縮パラメータ、
Ｋ…圧縮サイズの表示、Ｌ…元画像ビュー、Ｍ…ＪＰＥＧ画像プレビュー、
Ｎ…品質差分値の表示、Ｏ…領域の指定、Ｐ…領域のサイズ表示。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a storage / display control technique of lossy compression such as JPEG and MPEG of an image, and for example, a storage preview method and apparatus in Lossy compression for compressing, storing and displaying an image of a scanner utility, filing software, digital camera, etc. And a compression ratio prediction method.
[0002]
[Prior art]
For efficient storage of color images, Lossy (degraded image quality) compression such as JPEG is an effective means. Generally, when the compression ratio is increased in order to reduce the file size as much as possible, the lossy compression tends to cause a significant deterioration in image quality. The user needs to adjust the compression (or quality) parameters according to the content of the document and the purpose of use while balancing the compression ratio and the image quality degradation.
However, in general, the compression size and image quality cannot be confirmed unless the image is compressed and stored once and then reopened (decompressed).
[0003]
Therefore, there is a problem that trial and error are required to obtain the optimum value, and it takes time and effort. To solve this, there are some that allow you to adjust the quality parameter while checking the preview display at the time of saving, but since the entire target image is actually compressed and decompressed, the image is displayed in a relatively small size Is effective, but when the image size becomes large, such as A4-400 dpi (about 46 MB) or A3-400 dpi (about 92 MB), the processing speed becomes extremely slow, and it takes time to reach the desired image quality. There is a problem that it is not practical.
[0004]
In some digital cameras and the like, the JPEG compression parameter can be adjusted in several steps such as Economy / Normal / Fine, but the parameter (image quality) cannot be adjusted after checking the image quality after the image is stored with the parameters set before shooting.
[0005]
As a technique proposed in the related art, there is, for example, an image processing apparatus and method described in JP-A-2001-223921. This is a method that allows the user to confirm the compressed image data by displaying the expanded image after compression encoding before recording the image data on the recording medium.
However, this method has a preview function, but as described above, when the image size is large, the processing speed becomes extremely slow, and there is a problem that it takes time and effort.
[0006]
Further, for example, there is a camera system, an image encoding device, and an image decoding device described in Japanese Patent Application Laid-Open No. 2002-112086, which generates thinned-out data in a photographing unit, converts this data into a digital signal, This is a device that displays on a monitor via an A / D converter after being compressed by an image compression circuit, calculates a code amount, predicts a coded data amount of a full image, and determines a quantization table.
However, although this device can predict the compression size, as described above, it can only be adjusted in several steps, and cannot see the image before shooting, making predictions before shooting or making fine adjustments. No adjustments can be made.
[0007]
Also, for example, there is an image processing apparatus and method described in JP-A-2002-330293, which compresses and stores a block unit obtained by dividing image data into a predetermined size, and stores an encoded image according to a compression process. In this method, a new compression parameter is set based on the amount of data, and a data compression process corresponding to a predetermined file size is performed.
Even in this method, the amount of compressed data can be predicted, but as described above, when the image size is large, the processing speed becomes extremely slow, it takes time and effort, and it is not practical. is there.
[0008]
[Patent Document 1]
JP 2001-223921 A
[Patent Document 2]
JP 2002-112086 A
[Patent Document 3]
JP-A-2002-330293
[0009]
[Problems to be solved by the invention]
As described above, in the conventional technique, generally, the compression size and image quality cannot be confirmed unless the image is once compressed and stored and further decompressed. Therefore, there is a problem that trial and error is required to obtain the optimum values of the compression size and the image quality, and it takes time and effort. As a solution to this, there is a method that can adjust the quality parameter while checking the preview display at the time of saving, but since the entire target image is actually compressed and expanded, it is displayed, so for images with relatively small size, Although effective, there is a problem in that when the image size is large, the processing speed becomes slow and it takes time to reach a desired image quality, which is not practical.
[0010]
(Purpose)
SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional problems and to provide a preview method, an apparatus, and a compression method for lossy compression that can adjust quality (compression) parameters at a very high speed while previewing image quality and compression size before storage. The purpose is to provide a rate prediction method.
[0011]
[Means for Solving the Problems]
According to the save preview method in Lossy compression of the present invention, when an image is saved in a Lossy compression format, the entire image is processed by compressing and expanding only a displayed portion (a part of the image) and displaying the image on a screen. Preview saved results (image quality) faster than
[0012]
Also, by estimating the compressed size of the entire image from the compressed size of only the display part and displaying the image at the same time, the user can preview while checking the image quality and the compression ratio.
[0013]
In addition, by processing only the display portion instead of processing the entire image, high-speed processing is performed, so that the user can quickly and accurately find the target parameter setting value.
When only the display portion is processed, an accurate compressed size cannot be obtained. However, in the present invention, random or arbitrary arbitrary portions other than the display portion are sampled, and a more accurate compressed size is obtained at high speed.
[0014]
In a digital camera or the like, the image quality (Normal / Fine, etc.) cannot normally be switched after photographing because photographing is first performed after setting the quality. Obtain an image according to
(1) Some parts are sampled and compressed, and the compression ratio for each area is measured. It is assumed that the portion having a poor compression ratio is a portion where the image quality is severely degraded, and the portion is enlarged and displayed.
(2) Optimum parameter adjustment is performed by the method described in the above [0013], and the desired image quality and size are stored / stored.
In the present invention, the quality difference value is a value obtained by calculating the sum of the difference between the original image and the compressed preview image for each pixel as a ratio from the data of the entire pixel.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
(overall structure)
FIG. 1 is a schematic diagram of the overall configuration of the present invention, and FIG. 2 is a detailed diagram of each processing unit in FIG.
As shown in FIG. 1, it is assumed that an image to be lossy-compressed is held in the original image storage unit a. In the input / output device 1, the input control unit e and the display control unit k display an image and display a compression size, and input a change in display magnification, designation of a display position scroll, designation of a compression parameter, and the like. I do.
[0016]
There is provided a cutout control unit b for cutting out only a portion to be displayed and a portion to be sampled from the original image storage unit a. Further, a compression / decompression control unit g for performing Lossy compression and decompression processing is provided. Further, the storage units c and d for the cut-out image of the display portion and the cut-out image of the sampling image, the storage units h and i for temporarily storing the compression results of the display image and the sampling image, and the data once compressed are expanded. That is, the temporary storage unit j is provided for storing the preview image whose image quality has deteriorated as a result of the lossy saving.
[0017]
As shown in FIG. 2, the configuration of the processing system mainly includes a main control unit f, an original image storage unit a, a cutout control unit b, a cutout image storage units c and d, a compression / decompression control unit g, and compressed data. The storage units h and i, the expanded image storage unit j, the display control unit k, the input / output device l, and the input control unit e are arranged. The cutout control unit b includes a display size magnification acquisition unit b-1, a cutout position calculation unit b-2, and a cutout processing unit b-3. The compression / expansion control unit g includes a compression processing unit g-1, an expansion processing unit g-2, and a compression size (rate) acquisition unit g-3. The display control unit k includes a display position detecting unit k-1, a scaling unit k-2, and a drawing control unit k-3. The input control unit e includes a scroll and magnification operation detection unit e-1 and a compression parameter input detection unit e-2 (corresponding to claim 13).
[0018]
(1) Lossy compression preview (corresponding to claim 1)
FIG. 3 is a diagram showing an example of a JPEG storage preview screen according to the present invention.
In FIG. 3, the original image is displayed in the entire display view A. In this example, the entire image of the image held in the original image holding unit a is displayed as a thumbnail. A part of the image is displayed in the main view B, and the displayed part can be scrolled by a scroll bar operation, a mouse trap operation, or the like. The display magnification can be changed by a display magnification change control H. The area displayed on the main view B is rectangularly displayed as the area C currently displayed on the entire display view A. The area C is an area automatically displayed in accordance with the display of the main view B by a scroll operation or a display magnification operation. When the parameter is changed in the compression parameter designation control D, a preview of the compression result is instantaneously displayed in the main view B, and the compression size and compression ratio are displayed in the display area E of the expected size and compression ratio. When the confirm button G is pressed, JPEG storage is performed using the parameters (image quality) at that time.
[0019]
The detailed operation will be described below with reference to FIGS.
The compression parameter input from the input / output device 1 is notified to each control unit via the compression parameter input detection unit e-2 and the main control unit f. The scroll specification operated on the main view B and the display magnification specified by the display magnification change control H are detected by the scroll & magnification operation detection unit e-1, and are output to the cutout control unit b via the main control unit f. The control unit k is notified. In the clipping control unit b, a clipping position required by the clipping position calculation unit b-2 is calculated from the current scroll position, display magnification, screen size, and the like.
[0020]
That is, the position and size of the portion displayed on the screen are calculated. Based on the result, the image is cut out by the cut-out processing unit b-3 and stored in the cut-out image storage unit c. The extracted image is compressed by the compression processing unit g-1, and is temporarily stored in the compressed data storage unit i. Immediately after the compression is completed, the data is decompressed by the decompression processing unit g-2 and written into the decompressed image storage unit j. In the display control unit k, the display position detection unit k-1 determines an area that requires drawing, and the drawing control unit k-3 draws the image while scaling the image in the scaling processing unit k-2 as necessary. You. At the same time, a compressed size (ratio) acquisition unit g-3 acquires the compressed data size stored in the compressed data storage unit i, calculates a compression ratio and an estimated compressed size when the entire image is compressed, and displays the compressed data. The screen is displayed via k.
[0021]
The compression ratio and the estimated compression size are calculated by the following formulas.
Original image size = W * H pixel,
Display image size (equivalent magnification) = dW * dH pixel
Display part compression size = C byte
Then, for example, in the case of 24-bit full color (1 pixel = 3 bytes)
Compression rate (%) = C * 100 / (dW * dH * 3)
Expected compression size (byte) = W * H * C / (dW * dH)
Processing performance is improved as follows as compared with the case of processing the entire image.
For example, when displaying an image of A4-400 dpi (3307 * 4677 pixel) on a screen of 1024 * 768 pixel,
Display pixel number / Total pixel number = 1024 * 768 / (3307 * 4677) = 0.051
The processing can be realized in about 5% of the processing time for the entire processing.
[0022]
In FIG. 3, the image quality is good, but the expected compression size is 651 KB. In FIG. 4, the size is reduced to 182 KB, but the image quality is poor. In FIG. 5, the image quality was almost satisfactory, and the size was 242 KB, which was a satisfactory result. In this way, the user can find the most balanced parameter values while checking the image quality and the compression size.
[0023]
(2) Improvement of accuracy of compression size (corresponding to claim 2)
3 and FIG. 7 are the same as the compression parameter = 100, but due to the difference in the display position, the estimated compressed size is about twice as large as 651 KB in FIG. 3 and 1545 KB in FIG. This is because the compactness and characteristics of the image differ depending on the display position, so the compressed size also fluctuates, which is manifested as a difference in the expected compressed size, and the exact compressed size of the entire image is determined only from the compression ratio of the display part. It turns out to be difficult to predict.
Therefore, as shown in the original image storage unit a of FIG. 1, sampling is performed at several places other than the display position from the original image, and a temporary compression process is performed. Expect a high compressed size. In the example of FIG. 1, the rectangle of the black frame shown in the original image storage unit a indicates the sampling position, and in this example, one large area for display and three small areas sampled are shown.
[0024]
The sampling position is calculated by the cutout position calculation unit b-2 based on the information of the display size / magnification acquisition unit b-1 shown in FIG. As the sampling position, random sampling or an arbitrary position determined in advance so as to have an equal interval is selected. In the case of JPEG compression, since processing is performed in units of 8 * 8 pixels, the size and position per sampling point are also set in units of 8 * 8 pixels so that there is no difference in processing the entire image. The 8 * 8 pixels per sampled and extracted image are stored in the sampled and extracted image storage unit d, and stored in the compressed data storage unit h of the sampled image via the compression processing unit g-1. Thereafter, the compressed size (ratio) obtaining unit g-3 obtains the total of the compressed sizes of the respective sampling data.
[0025]
The calculation formula is as follows.
Expected compression size = original image area * total sampling compression size / total sampling area
According to the present invention, it is possible to always calculate and display a more accurate compressed size regardless of the display position and the magnification, so that after confirming in the preview display, when actually saving, the compressed size is greatly different. Can be avoided.
[0026]
Another feature of the present invention is that the processing load is small. When the above-mentioned A4-400 dpi image is displayed on a screen of 1024 * 768 pixels, when 1000 other locations are sampled, if one sampling area is 8 * 8 pixels,

Thus, there is only a difference of 0.004 = 0.4% as compared with the case where no sampling is performed, and it can be seen that the compression size can be predicted with higher accuracy without lowering the processing performance in this processing. .
[0027]
(3) Sampling result cache (corresponding to claim 3)
In the case where the user scrolls the display portion or changes the display magnification without changing the compression parameter, the sampling image of (2) is adopted as the display image, and the compression once processed for display and sampling is performed. / Enhance efficiency by holding the decompressed data without discarding it. For this purpose, the cut-out display image storage unit c, the compressed data storage unit i, and the decompressed image storage unit j manage the image of the display part in a state of being divided into 8 * 8 pixels. The cutout control unit b cuts out the display image by dividing it into 8 * 8 pixels. The compression / decompression processing is performed for each divided area, and is stored in the decompressed image storage unit j. The display control unit k performs a display output process on these divided images on a region basis.
[0028]
For example, consider a case where a scroll operation is performed. Normally, it is necessary to cut out, compress, and expand the entire display area in accordance with a new display position generated by scrolling. However, if a sampling image already exists, it is not necessary to process the entire area, and only nonexistent pixels are newly extracted, compressed, and expanded. If a sampled image exists, the decompressed image is prepared in the decompressed image storage unit j via the decompression processing unit g-2 from the compressed data storage unit h of the sampled image, and is used as a display image. By holding the data in the compressed data storage units h and i or the decompressed image storage unit j, even if the display area is changed by scrolling or changing the magnification, the display preview can be performed quickly and efficiently without reprocessing. . In addition, the accumulation of the compressed data gradually increases the accuracy of the estimated compression size.
[0029]
(4) Automatically display places where image quality degradation is large / small (corresponding to claim 4)
As a general tendency of compression, complicated data (image) has a low compression ratio, and simple data (image) has a high compression ratio. The JPEG compression has a feature that a high compression ratio is obtained by cutting a high-frequency component that is hardly perceived by a human, and the cut of the high-frequency component appears as deterioration in image quality. Therefore, the more complicated the data, the more the change is severe, the more high frequency components, and the more the image quality tends to deteriorate. Therefore, it can be predicted that the lower the compression ratio, the more the image quality deteriorates.
In addition, the degree of image quality degradation can be directly obtained by decompressing the sampling compressed data and calculating the difference between the original image and the pixel unit.
[0030]
Quality difference value (%) = Σ (pixel value of original image−value of decompressed pixel) * 100 / (number of pixels * pixel MAX value)
If 0, there is no image quality degradation, and the larger the value, the more severe the degradation
In the process (2), a position where the compression ratio is the lowest and a position where the compression ratio is the highest are detected from the sampled compressed data. Alternatively, the position where the quality difference value is the largest and the position where the quality difference value is the smallest are detected. By automatically displaying those detected positions, the user can perform an efficient operation when setting image quality (compression) parameters.
[0031]
FIGS. 3, 6, 8, and 9 are screen diagrams showing the embodiment.
First, when the upper left end of the image is displayed as shown in FIG. 3, it is determined that the image quality deterioration is more severe than the sampling compression data, and the image is automatically displayed as shown in FIG.
In order to perform the image quality adjustment in more detail, as shown in FIGS. 8 and 9, there is shown a screen for automatically enlarging and displaying a portion determined to have the most severe image quality deterioration and adjusting the image quality.
As one of the automatic display methods, a method that allows the user to determine the image quality while viewing the balance by simultaneously displaying both the part where the image quality assumed by the above determination method is considered to be the worst and the part where the image quality is considered to be the best is considered. is there.
[0032]
(5) Accurate compressed size (corresponding to claim 5)
In the embodiment corresponding to the second aspect of the present invention, it is possible to estimate a more accurate compressed size by increasing the number of samplings, or in the embodiment corresponding to the third aspect, by scrolling and displaying the entire image. However, in the following case, a method of compressing the entire image is effective other than the method of the first aspect.
[0033]
-The original image size is small, the compression processing time of the entire image is short (not much larger than the screen size),
-To simplify the entire process (when not using the method of claims 2 and 3)
-In a system that can effectively utilize the idle time of the CPU that can perform multitasking, if it is predicted that the idle time of the CPU will be long, such as waiting for user operation
-When an accurate compressed size is required (for example, when trying to fit on a 1.44 MB flexible disk, if it is desired to verify whether it fits in).
[0034]
In such a case, the entire image is compressed automatically in the background or by a user operation to obtain an accurate compressed size. When file saving is designated in this state (current compression parameter), the processing time can be reduced by writing the already generated compressed data as it is without performing compression processing.
[0035]
(6) Accurate estimation of compressed size (corresponding to claim 6)
FIG. 10 is a diagram illustrating a relationship between a compression parameter and a compression size in JPEG compression. 11 to 19 are characteristic curve diagrams showing a relationship between a compression parameter and a compression size.
The compression parameter qFactor is a value that determines a quantization table in JPEG compression, and becomes a standard quantization table when qFactor = 100. The whole in each figure represents a compressed image of the entire image. The areas A and B represent the result of extracting and compressing only a part of the areas.
[0036]
In other words, the regions A and B represent the same state as that in which only the display portion in claim 1 is extracted and compressed. The sub-sampling represents a sub-sampling ratio of a luminance component and a chrominance component in the horizontal and vertical directions. 2 * 2 is the case where the brightness information and the color information are set to the same half, and 4 * 2 is the case where the information is set to 1/4 and 1/2 respectively.
Since light and dark are sensitive to human eyes and colors are insensitive to human eyes, light and dark information is １ ／ and color information is １ ／.
The graphs of FIG. 11 and FIG. 12 are diagrams showing a comparison between the whole and the whole (4 * 2) and a comparison between the regions A and B. From FIGS. 11 and 12, it can be seen that the same tendency is obtained regardless of the whole image or a part of the image and regardless of factors such as subsampling.
[0037]
The graph of FIG. 13 is a graph 3 in which the horizontal axis represents the size of the entire image compressed and the vertical axis represents the size of the compressed regions A and B only. From the graph 3 in FIG. 13, it can be seen that the two are in a proportional relationship, and if the coordinates of the two points are known, an approximate linear equation can be obtained.
More strictly, the slope of the straight line slightly changes from qFactor = 100 (standard value). This is shown in graphs 4 and 5 of FIGS. In the graphs 4 and 5, it can be seen that a highly accurate approximation formula of R square value = 0.9987 to 0.9999 can be obtained (R square value indicates the degree of variation of approximation. In the case of 1, there is no variation). , 0, the variation increases and the approximation accuracy decreases). This tendency does not change even when the sub-sampling ratio becomes 4: 2. The graph 7.8 in FIG. 17 and FIG. 18 also shows that the R-squared value is 0.9999 to 1.0000, and it can be seen that the R square value can be almost completely approximated.
[0038]
Therefore, if it is possible to measure the compressed size of the entire image and the display portion at a total of three places with qFactor = 100, the compressed size of the entire image can be predicted from the compressed size of the display portion.
Further, as shown in a graph 9 in FIG. 19, the compressed data for each area also has a linear approximation relationship. Therefore, in the processing according to claims 2 and 3, if the approximate overall compressed size can be measured from the sampled area in a total of three places in the same manner with qFactor = 100, then the approximate compressed size of the display part can be determined. Can predict the overall compression size of
[0039]
(7) Image quality adjustment after shooting (corresponding to claim 7)
In a device such as a digital still camera that compresses and saves immediately after shooting, the quality (compression) parameter is shot, compressed, and saved with a preset value. Usually, in order to reliably control the number of remaining shots, any image is subjected to a compression retry process until the same compression size is reached, and an appropriate quality parameter is searched for and finally saved, resulting in waste of processing. .
[0040]
However, by applying the present invention, the user can save the image with the optimal compression parameters while checking the image quality and the number of remaining images after shooting.
FIG. 20 shows an embodiment of the digital camera screen. FIG. 20 shows a state in which a portion considered to have the worst image quality is enlarged and displayed based on the method of claim 4 after photographing.
On the screen shown in FIG. 20, the image quality is good, but the compressed size is too large, so that the number of remaining shots is one.
[0041]
Therefore, as shown in FIG. 21, when the compression parameter is reduced, the number of remaining shootable images can be increased up to 10, but this results in too poor image quality. Therefore, as shown in FIG. 22, the compression parameters were slightly increased, and the remaining number of images to be photographed was secured at eight while the image quality was moderately secured. In this way, the quality (compression) parameter can be set while adjusting the image quality and the number of remaining shots according to the user's intention. Normally, the same compression size for all images tends to contradict that the finer the image, the lower the quality parameter and the lower the image quality, and the lower the quality, the higher the quality parameter and the higher the quality. By allowing the user to make adjustments while checking the image quality, shooting, compression, and storage that meet the user's purpose can be performed.
[0042]
(8) Simple display mode (corresponding to claim 8)
In the method according to claim 1, since the display target area is cut out and subjected to compression processing, when the reduction ratio is large such as in an entire display mode in which the entire image is displayed, the entire image or most of the image is eventually subjected to compression processing. As a result, processing efficiency and speed cannot be improved. In addition, many noises and the like due to image deterioration in Lossy compression such as JPEG are minute, and it is not possible to check the image quality in reduced display. Therefore, according to the method of the present embodiment, when a reduced image is displayed, the reduced image is created, and the reduced and compressed image is displayed at 100%.
As a result, the original image quality is not accurately represented, but an image serving as an index for image quality adjustment can be displayed at high speed with a small amount of processing.
[0043]
(9) Comparison display, quality difference value (corresponding to claim 9)
FIG. 23 is a diagram showing an embodiment according to claim 9 of the present invention.
In FIG. 23, the original image and the JPEG compressed image are compared and displayed using the method of the present invention so that the image quality can be adjusted more appropriately. In addition, the degree of image quality deterioration is numerically displayed as a quality difference value so that objective evaluation can be performed. The quality difference value is obtained by the following equation. In the case of 0, there is no difference = no image quality degradation.
Quality difference value (%) = Σ (each pixel value of original image−each pixel value of JPEG compressed image) * 100 / (number of pixels * max value of pixel)
[0044]
(10) Preview of a partial area (corresponding to claim 10)
FIG. 24 is a diagram showing an embodiment according to claim 10 of the present invention.
Only a partial area is selected, and the result of compression and expansion according to the method of claim 1 is displayed. Only necessary parts of the entire image can be saved in JPEG, and quality (compression) parameters can be adjusted while previewing the image quality at that time.
[0045]
(11) Other embodiments (corresponding to claims 11 and 12)
As another embodiment of the present invention, there is a method of simply performing prediction of the compression size (rate) using the processing of the present invention without previewing.
The present invention also includes a method of previewing the image and the remaining capacity while reducing the data itself by trimming, resizing, or the like without changing the image quality.
[0046]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(A) In the embodiment corresponding to the first aspect, the state of image quality deterioration caused by lossy compression can be previewed at high speed. For example, even a large-capacity image such as A3-400 dpi (data size of about 92 MB) requires only a processing amount corresponding to the display size, so that the processing speed is high. You can know the approximate data size when the data is compressed and saved at the same time as the preview.
[0047]
(B) In the embodiment corresponding to claim 2, in the operation and effect of the above (a), the error accuracy of the compressed data size that can be known at the same time as the preview can be improved without lowering the processing speed.
(C) In the embodiment according to the third aspect, the shredded compressed data is cached every time the display scrolling or the display magnification is changed, so that the processing speed is gradually improved and the error accuracy of the compressed data size is improved. To go.
[0048]
(D) In the embodiment corresponding to the fourth aspect, the user can automatically display or magnify the part where the image quality deterioration due to lossy compression is considered to be the most severe or the part where the image quality deterioration is considered to be the least. Image quality determination and compression parameter setting can be more efficiently assisted.
(E) In the embodiment according to the fifth aspect, when the entire image is compressed in order to obtain an accurate compressed size, data can be stored without performing compression processing again (that is, without waiting time).
[0049]
(F) In the embodiment according to the sixth aspect, the accurate compressed data size can be easily calculated without performing complicated processing every time.
(G) In an embodiment corresponding to claim 7, in an input device such as a digital camera which is directly lossy-compressed after photographing, a user designates a quality (compression) parameter while comparing image quality with remaining number of recordable images after photographing. it can.
[0050]
(H) In the embodiment corresponding to the eighth aspect, the simple mode makes it possible to obtain a measure of compression parameter setting while maintaining a high processing speed, although the image quality is not accurate. Since the image quality degradation in JPEG compression is minute noise such as mosquito noise and block noise, it cannot be confirmed by the method of claim 1 in reduced display, but can be confirmed in the simple mode (the present invention).
[0051]
(I) In the embodiment corresponding to the ninth aspect, the user can visually confirm the state of image quality deterioration by comparison display, and can quantitatively know the amount of deterioration by the quality difference value, so that compression is efficiently performed. It is possible to set parameters.
(J) In the embodiment corresponding to claim 10, when only a partial area of the image is stored, or when the compression ratio and the compression rate are adjusted in accordance with the different characteristics for each area such as a photograph part, a graph figure part, and a character part of the pamphlet image For example, when the image quality is changed and saved, the preview for each area can be performed.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a compression / decompression processing system according to an embodiment of the present invention.
FIG. 2 is a detailed layout diagram of each processing unit in FIG. 1;
FIG. 3 is a diagram of a JPEG storage preview screen showing an embodiment of the present invention.
FIG. 4 is a screen view when the compression size is small but the image quality is poor.
FIG. 5 is a screen diagram in which the balance between image quality and compression size is adjusted.
FIG. 6 is a screen view for automatically displaying an area having a low compression ratio.
FIG. 7 is a screen view when comparing the compression sizes of different areas with the same compression parameter.
FIG. 8 is a screen diagram in which a portion having poor image quality is automatically enlarged and displayed.
FIG. 9 is a screen diagram of image quality adjusted after automatic enlargement display.
FIG. 10 is a diagram showing a relationship between JPEG compression sizes.
FIG. 11 is a graph 1 showing a relationship between a compression parameter and a compression size (overall image).
FIG. 12 is a graph 2 showing a relationship (region) between a compression parameter and a compression size.
FIG. 13 is a graph 3 showing the relationship between the overall compression size and the region compression size.
FIG. 14 is a graph 4 showing the relationship between the whole and the area compression size.
FIG. 15 is a graph 5 showing the relationship between the whole and the area compression size.
FIG. 16 is a graph 6 showing a relationship between compressed sizes.
FIG. 17 is a graph 7 showing a relationship between compressed sizes.
FIG. 18 is a graph 8 showing a relationship between compressed sizes.
FIG. 19 is a graph 9 showing a relationship between region compression sizes.
FIG. 20 is a diagram illustrating an example of a digital camera screen according to the present invention.
FIG. 21 is a diagram illustrating an example of a digital camera screen (the number of remaining images is large, but the image quality is poor) according to the present invention.
FIG. 22 is a diagram showing an example of a digital camera screen (improving image quality while securing the remaining number).
FIG. 23 is a diagram illustrating a display example of a comparison display and a difference value according to the present invention.
FIG. 24 is a diagram showing an example of a quality preview of only a partial area in the present invention.
[Explanation of symbols]
a: original image storage unit, b: cut-out control unit, c: cut-out image storage unit of display part,
d: sampling cut-out image storage unit, e: input control unit, f: main control unit,
g: Compression / expansion control unit, h: Sampling image compressed data storage unit,
i: compressed data storage unit for display image, j: decompressed image storage unit, k: display control unit,
l: input / output device, b-1: display size magnification acquisition unit,
b-2: cutout position calculation unit, b-3: cutout processing unit,
e-1: scroll & magnification operation detecting unit, e-2: compression parameter input detecting unit,
g-1: compression processing unit, g-2: expansion processing unit,
g-3: compressed size (ratio) acquisition unit; k-1: display position detection unit;
k-2: scaling processing unit, k-3: drawing control unit, A: whole image view,
B: Main view, C: Currently displayed area,
D: Compression parameter designation control, E: Display area of expected size & compression ratio,
F: Accurate size calculation button, G: Confirm button,
H: display magnification change control, I: main view, J: compression parameter,
K: Compressed size display, L: Original image view, M: JPEG image preview,
N: display of quality difference value; O: designation of area; P: display of area size.

Claims (14)

In a save preview method for saving an image in a lossy compression format and displaying the image,
Compress and decompress only part of the displayed image,
Displaying the compressed and decompressed image on a screen;
And, based on the compressed size of all or only a part of the displayed image, estimate the compressed size of the entire image,
A storage preview method in Lossy compression, wherein an estimated compression size is displayed on a display screen to enable confirmation of image quality and a compression ratio. 2. The storage preview method according to claim 1, wherein:
In order to improve the accuracy of the estimated compressed size, a predetermined arbitrary position besides the display portion, or a plurality of small regions randomly extracted is compressed, and the entire image is compressed based on the compressed size. A storage preview method in Lossy compression, wherein a compression size is calculated, and a compression ratio of the entire image is calculated together with a compression ratio of a display image. 3. The storage preview method in Lossy compression according to claim 1 or 2,
When the image is processed in units of n * n pixels, and when there is no change in the lossy compression parameter, the compression result of each part of the displayed or scrolled display image is temporarily stored to display the display image, A saving preview method in Lossy compression, characterized in that the preview display becomes faster and a more accurate compression ratio is calculated sequentially each time scrolling or changing the display magnification is repeated. 3. The storage preview method according to claim 2, wherein:
The compression ratios of the extracted plurality of locations are measured, and a quality difference value expressing a difference in image quality at each coordinate of the plurality of locations by a numerical value is obtained.The position where the value of the compression ratio and the quality difference value is the worst, and Judging a good position, automatically displaying or enlarging the periphery of the position, and automatically displaying a position estimated to be most affected by image quality or a position estimated not to be affected in the entire image. A lossy compression storage preview method for facilitating user image quality determination. 3. The storage preview method in Lossy compression according to claim 1 or 2,
In order to accurately calculate the compressed size, the entire image is compressed according to an instruction from the user or automatically using the idle time of the CPU, an accurate size is obtained, and the information on the compressed size is temporarily stored. A method of saving preview in Lossy compression, characterized in that when temporarily saving and thereafter saving without changing compression parameters, the temporarily saved data is written as it is. 2. The storage preview method according to claim 1, wherein:
When the whole image processing is performed by the processing of claim 5 with two or more compression parameters, thereafter, an accurate compression size is calculated from only the compressed data of the display portion by an approximate expression, or
A substantially accurate compressed size is obtained in advance by the processing according to claim 2 or 3 using two or more compression parameters, and thereafter, an accurate compressed size is calculated only from the compressed data of the display portion by an approximate expression. Preview method in Lossy compression. 5. The storage preview method for lossy compression according to claim 1, wherein:
If the device to which the above processing is applied is an input device such as a digital camera that stores the image in lossy compression along with image capture, the data before compression is retained, and the image quality and remaining image capture after image capture by the user. A saving preview method in Lossy compression, wherein a compression parameter is specified so that the number of possible images can be confirmed. 2. The storage preview method according to claim 1, wherein:
In the case of a display magnification such that most areas are displayed, such as when the entire image is reduced and displayed on the display screen, a function of reducing the sampling to the display magnification when cutting out the display image is provided with a simple display mode, The reduced image is compressed / decompressed and previewed, or
A saving preview method in Lossy compression, wherein the mode is automatically switched to the simple mode when the display of the reduced magnification is displayed so that the standard of the image quality parameter setting can be obtained in the simple display mode. A storage preview method for lossy compression according to any one of claims 1 to 7,
On the display screen, the original image and the compressed preview image are displayed side by side to clarify the degree of deterioration of the image quality, and at the same time, display the quality difference value expressing the difference of the image quality by numerical values, and provide a guide for the user's image quality evaluation. A storage preview method in Lossy compression. 2. The storage preview method according to claim 1, wherein:
By specifying one or more ranges of an arbitrary region of the image and compressing and storing only the portion of the region, for example, in the case of compressing and storing only a photograph of a part of a pamphlet, a compressed preview of the region portion A storage preview method in Lossy compression, characterized by displaying. In a save preview method for saving an image in a lossy compression format and displaying the image,
The method according to any one of claims 1 to 3, wherein a compression size and a compression ratio of the entire image are estimated based on a compression size of only a part of the image, and the compression size and the compression ratio are determined regardless of the preview display of the image. Alternatively, a compression ratio predicting method in Lossy compression, characterized by displaying a remaining capacity of a storage device. The storage preview method for lossy compression according to claim 7,
In the image display, the lossy compression is characterized in that the data size itself is reduced by trimming or other unnecessary portion deletion or size reduction processing or the like in order to secure the remaining capacity without changing the image quality, and previewing is performed. Save preview method in. In a save preview device for saving an image in the Lossy compression format and displaying the image,
An input / output device for inputting / outputting an original image, an input control unit for detecting a scroll and a magnification operation of the input / output image, and detecting a compression parameter input; an original image storage unit for storing the original image; Of the extracted image, obtains the display size magnification, and calculates the extracted position, the extracted image storage unit that stores the extracted image, and compresses and expands the extracted image. A compression / decompression control unit for obtaining a compression ratio, a compressed data storage unit for storing compressed data, a decompressed image storage unit for storing decompressed images, and a display for detecting a display position, performing scaling processing, and drawing. A storage preview device for lossy compression, comprising: a control unit. In a digital camera device having a save preview function of saving an image in a lossy compression format and displaying the image,
A storage unit for storing data before compression, a cutout and compression / expansion control unit for executing the storage preview method according to any one of claims 1 to 4, and a user confirming image quality after shooting and the remaining number of shootable images. A digital camera device having a save preview function in lossy compression, wherein the digital camera device has means for causing a compression parameter to be specified.

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