JPH0832060B2 - Color image processing method - Google Patents
Color image processing methodInfo
- Publication number
- JPH0832060B2 JPH0832060B2 JP60056630A JP5663085A JPH0832060B2 JP H0832060 B2 JPH0832060 B2 JP H0832060B2 JP 60056630 A JP60056630 A JP 60056630A JP 5663085 A JP5663085 A JP 5663085A JP H0832060 B2 JPH0832060 B2 JP H0832060B2
- Authority
- JP
- Japan
- Prior art keywords
- saturation
- color image
- saturation range
- output device
- color
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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- Facsimile Image Signal Circuits (AREA)
- Color Image Communication Systems (AREA)
- Dot-Matrix Printers And Others (AREA)
- Color, Gradation (AREA)
Description
【発明の詳細な説明】 〈技術分野〉 本発明は入力カラー画像が有する彩度範囲と出力装置
の再現彩度範囲が異なる場合のカラー画像処理方法に関
する。Description: TECHNICAL FIELD The present invention relates to a color image processing method in a case where a saturation range of an input color image and a reproduction saturation range of an output device are different from each other.
〈従来技術〉 従来のカラー画像処理方法では、入力カラー画像の彩
度範囲を出力装置、例えばプリンタの再現彩度範囲と合
わせる為に、再現彩度を超えた部分は再現彩度の最大値
に圧縮していた。<Prior Art> In the conventional color image processing method, in order to match the saturation range of the input color image with the reproduction saturation range of the output device, for example, the printer, the portion exceeding the reproduction saturation is set to the maximum value of the reproduction saturation. It was compressed.
その為入力画像の彩度の連続性が損なわれ、調子が変
化した出力画像が得られていた。Therefore, the continuity of the saturation of the input image is impaired, and an output image with a changed tone is obtained.
〈目的〉 本発明は上述の如き従来技術の欠点に鑑み、入力画像
の彩度分布に応じて最適なカラー処理を施こすことが可
能なカラー画像処理方法の提供を目的としている。<Purpose> In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a color image processing method capable of performing optimum color processing according to the saturation distribution of an input image.
〈実施例〉 本発明を入力R,G,Bカラー信号をハードコピーするカ
ラープリンタに適用した例について説明する。<Example> An example in which the present invention is applied to a color printer that hard copies input R, G, B color signals will be described.
第１図は本実施例のカラープリンタの信号処理ブロツ
ク図である。図において、11は入力R,G,B信号から輝度
信号Y,色差信号（Ｒ−Ｙ），（Ｂ−Ｙ）を得るエンコー
ダで次式の処理を行う。FIG. 1 is a signal processing block diagram of the color printer of this embodiment. In the figure, reference numeral 11 is an encoder for obtaining a luminance signal Y, color difference signals (RY), (BY) from input R, G, B signals, and performs the processing of the following equation.
12は色差信号（Ｒ−Ｙ），（Ｂ−Ｙ）から色相H,彩度
Ｃを得る演算回路で次式の処理を行う。 Reference numeral 12 is an arithmetic circuit for obtaining the hue H and the saturation C from the color difference signals (RY) and (BY), and performs the processing of the following equation.
13は各色相について彩度のヒストグラムをとる処理及
び彩度変換を行うCPUである。14はCPUの処理プログラム
を格納したROM、15はヒストグラムデータ及びその他CPU
13の処理に必要な値を記憶するRAMである。16は輝度信
号Y,色相H,変換された彩度Ｃ′からマスキング処理を行
い、イエローYe,マゼンタMa,シアンCyの各原色信号を得
るマスキング回路、18Ye,18Ma,18Cyは各原色を記録する
記録ヘツドである。 Reference numeral 13 denotes a CPU that performs processing for obtaining a histogram of saturation for each hue and saturation conversion. 14 is a ROM storing the CPU processing program, 15 is a histogram data and other CPU
It is a RAM that stores the values necessary for the processing of 13. Reference numeral 16 is a masking circuit that performs masking processing from the luminance signal Y, hue H, and the converted saturation C ′ to obtain each primary color signal of yellow Ye, magenta Ma, and cyan Cy, and 18Ye, 18Ma, and 18Cy record each primary color. It is a record head.
以下、第２図のフローチヤートに従い、CPU13の処理
動作について説明する。The processing operation of the CPU 13 will be described below with reference to the flow chart of FIG.
まずステツプS1で入力カラー信号の一画面を構成する
全画素を対象として、各色相Ｈについて彩度のヒストグ
ラム（頻度分布）をとる。次にステツプS2で各色相Ｈに
ついて最大彩度C(H)max，最小彩度C(H)minを検出する。
そしてS3でC(H)maxとC(H)minの差と予め測定したおいた
カラープリンタの各色相Ｈについての最大再現彩度C(H)
Lとを比較する。S3でC(H)max−C(H)min＞C(H)Lの場合に
はステツプS4で次式に従い、彩度の圧縮処理を行い出力
彩度Ｃ′（Ｈ）を得る。First, in step S1, a histogram (frequency distribution) of saturation is obtained for each hue H for all pixels constituting one screen of the input color signal. Then, in step S2, the maximum saturation C (H) max and the minimum saturation C (H) min are detected for each hue H.
Then, in S3, the difference between C (H) max and C (H) min and the maximum reproducible saturation C (H) for each hue H of the color printer measured in advance
Compare with L. If C (H) max- C (H) min > C (H) L in S3, the saturation is compressed according to the following equation in step S4 to obtain the output saturation C '(H).
この様にして第３図（１）に示す如き彩度の圧縮処理
が行われる。従って色調の連続性が損なわれることなく
彩度の圧縮が可能となる。特に第３図（１）に示す彩度
圧縮を行う場合には入力画像のうち、最低の彩度のレベ
ルはそのまま出力されるので、例えば鮮やかな彩度の高
い連続した色調の背景をバックに比較的彩度の低い人間
の顔が撮像される画像であっても、彩度圧縮処理により
人間の顔の彩度が低下し、顔色が悪くなってしまうこと
を未然に防止し、かつ彩度の高い背景の色調の連続性を
損なうこともない。 In this way, the saturation compression processing as shown in FIG. 3 (1) is performed. Therefore, the saturation can be compressed without impairing the continuity of the color tone. In particular, when the saturation compression shown in FIG. 3 (1) is performed, the lowest saturation level of the input image is output as it is, so that, for example, a background of a continuous tone having a bright saturation is used as a background. Even if an image of a relatively low-saturation human face is captured, it is possible to prevent the saturation of the human face from being reduced due to the saturation compression processing, and prevent the complexion from becoming worse. It does not impair the continuity of the color tone of high backgrounds.
次にC(H)max−C(H)min≦C(H)LとS3で判断され、S6でC
(H)L≧C(H)maxと判断された場合には、第３図（２）に
示す如く、入力画像の彩度範囲がプリンタの再現彩度範
囲に完全に含まれるので、彩度変換を行わずに、S7でＣ
（Ｈ）をそのままＣ（Ｈ′）として出力する。斯かる構
成により入力画像の特性をそのまま活かすことができ
る。Next, C (H) max −C (H) min ≤ C (H) L is judged in S3, and in S6 C
If (H) L ≧ C (H) max is determined, the saturation range of the input image is completely included in the reproduction saturation range of the printer as shown in FIG. C in S7 without conversion
(H) is output as it is as C (H '). With such a configuration, the characteristics of the input image can be used as they are.
最後にC(H)max−C(H)min≦C(H)Lで、C(H)L＜C(H)max
とS6で判断された場合には、第３図（３）に示す如く、
入力画像の最大彩度側が出力再現彩度の最大値を超えて
いる。この場合は彩度が大きい方に偏っているのを活か
してS9で次式に従い分布全体を移動させる。Finally, C (H) max −C (H) min ≦ C (H) L , and C (H) L <C (H) max
If it is determined in S6, as shown in FIG. 3 (3),
The maximum saturation side of the input image exceeds the maximum value of the output reproduction saturation. In this case, the entire distribution is moved according to the following equation in S9 by taking advantage of the bias toward the larger saturation.
Ｃ（Ｈ）−（C(H)max−C(H)L）→Ｃ′（Ｈ） 斯かる手法により彩度の偏りをそのまま出力画像の彩
度の偏りとして再現できると共に、彩度範囲の絶対値は
変化せず自然な印象を視覚に与える。C (H) − (C (H) max −C (H) L ) → C ′ (H) With such a method, the saturation deviation can be reproduced as it is as the saturation deviation of the output image, and the saturation range The absolute value does not change and gives a natural impression to the visual sense.
こうしてステツプS4,S7,S9で得られたＣ′（Ｈ）をマ
スキング回路16にステツプS5,S8,S10で出力する。C '(H) obtained in steps S4, S7, S9 in this way is output to the masking circuit 16 in steps S5, S8, S10.
尚、本実施例においては各色相について彩度の変換を
行ったが、色相と明度の両方について彩度の変換を行え
ばより正確であるが、処理が複雑となる。Although the saturation is converted for each hue in this embodiment, it is more accurate if the saturation is converted for both hue and lightness, but the process becomes complicated.
又、輝度，色相，彩度信号としてY,H,Cを用いたが、
それに類するものであればよく、Lab＊,Luv＊等を用い
ることもできる。Also, Y, H, C were used as the luminance, hue, and saturation signals,
Anything similar to that may be used, and Lab *, Luv * and the like can be used.
又，本例では色相すべてについて処理を行ったが、特
定の色相に代表させて変換処理を行ってもよい。Further, in this example, the processing is performed for all the hues, but the conversion processing may be performed by representing a specific hue.
効果 本発明に依れば入力カラー画像信号の所定色相の彩度
範囲が出力装置の再現彩度範囲に含まれるか否かを予め
判定し、前記入力カラー画像信号の彩度範囲が出力装置
の再現彩度範囲に含まれないと判定された場合には前記
入力カラー画像信号の彩度範囲を前記出力装置の再現彩
度範囲内に色調の連続性が損なわれない様に圧縮して前
記出力装置に出力し、前記入力カラー画像信号の彩度範
囲が前記出力装置の再現彩度範囲に含まれると判定され
た場合には前記入力カラー画像信号の彩度範囲を圧縮す
ることなく前記出力装置に出力しているので入力カラー
画像信号の特性、彩度の状態をなるべく保存し、かつ出
力装置の再現彩度範囲内で画像全体の彩度の階調を再現
することが可能になり、再現彩度範囲が制限されたカラ
ープリンタ、あるいはカラーディスプレイ装置に極めて
有用である。Effect According to the present invention, it is determined in advance whether or not the saturation range of the predetermined hue of the input color image signal is included in the reproduction saturation range of the output device, and the saturation range of the input color image signal of the output device is determined. When it is determined that the color saturation range is not included in the reproduction saturation range, the saturation range of the input color image signal is compressed within the reproduction saturation range of the output device so that the continuity of the color tone is not impaired, and the output is performed. Output to the device, and when it is determined that the saturation range of the input color image signal is included in the reproduction saturation range of the output device, the output device without compressing the saturation range of the input color image signal Since it is output to, it is possible to save the characteristics of the input color image signal and the state of saturation as much as possible, and to reproduce the gradation of saturation of the entire image within the reproduction saturation range of the output device. Color printers with limited saturation range It is extremely useful for color display devices.
第１図は本実施例のカラープリンタの信号処理ブロツク
図、第２図は第１図のCPU13の処理フローチヤート図、
第３図は彩度の入出力ヒストグラムを示す図である。FIG. 1 is a signal processing block diagram of the color printer of this embodiment, FIG. 2 is a processing flow chart of the CPU 13 of FIG.
FIG. 3 is a diagram showing an input / output histogram of saturation.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０４Ｎ 1/60 5/91 Ｈ０４Ｎ 1/40 Ｄ 5/91 Ｈ Ｂ４１Ｊ 3/00 Ｂ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Office reference number FI Technical display location H04N 1/60 5/91 H04N 1/40 D 5/91 H B41J 3/00 B
Claims (1)
が出力装置の再現彩度範囲に含まれるか否かを予め判定
し、前記入力カラー画像信号の彩度範囲が出力装置の再
現彩度範囲に含まれないと判定された場合には前記入力
カラー画像信号の彩度範囲を前記出力装置の再現彩度範
囲内に色調の連続性が損なわれない様に圧縮して前記出
力装置に出力し、前記入力カラー画像信号の彩度範囲が
前記出力装置の再現彩度範囲に含まれると判定された場
合には前記入力カラー画像信号の彩度範囲を圧縮するこ
となく前記出力装置に出力することを特徴とするカラー
画像処理方法。1. A method of determining in advance whether or not a saturation range of a predetermined hue of an input color image signal is included in a reproduction saturation range of an output device, and determining a saturation range of the input color image signal of the output device. If it is determined that the input color image signal is not included in the saturation range, the saturation range of the input color image signal is compressed within the reproduction saturation range of the output device so as not to impair the continuity of the color tone, and is output to the output device. And outputs to the output device without compressing the saturation range of the input color image signal when it is determined that the saturation range of the input color image signal is included in the reproduction saturation range of the output device. A color image processing method comprising:
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60056630A JPH0832060B2 (en) | 1985-03-21 | 1985-03-21 | Color image processing method |
| US06/838,785 US4731662A (en) | 1985-03-21 | 1986-03-12 | Image processing method for processing an image signal differently depending on the range of an image characteristic thereof relative to the range within which an output device can reproduce the image characteristic |
| DE3609049A DE3609049C3 (en) | 1985-03-21 | 1986-03-18 | Image editing process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60056630A JPH0832060B2 (en) | 1985-03-21 | 1985-03-21 | Color image processing method |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7067785A Division JP2567214B2 (en) | 1995-03-27 | 1995-03-27 | Image processing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61214893A JPS61214893A (en) | 1986-09-24 |
| JPH0832060B2 true JPH0832060B2 (en) | 1996-03-27 |
Family
ID=13032625
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60056630A Expired - Lifetime JPH0832060B2 (en) | 1985-03-21 | 1985-03-21 | Color image processing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0832060B2 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0669438B2 (en) * | 1987-04-24 | 1994-09-07 | 株式会社東芝 | Endoscope device |
| JPS6354144A (en) * | 1986-08-25 | 1988-03-08 | 株式会社東芝 | Electronic endoscope apparatus |
| JPH06101854B2 (en) * | 1987-11-17 | 1994-12-12 | 三菱電機株式会社 | Color reproduction processing method |
| JPH0241271A (en) * | 1988-08-01 | 1990-02-09 | Fuji Xerox Co Ltd | Color image forming apparatus |
| JP2714027B2 (en) * | 1988-08-31 | 1998-02-16 | キヤノン株式会社 | Color image processing apparatus and color image processing method |
| JP2698493B2 (en) * | 1991-09-20 | 1998-01-19 | 大日本印刷株式会社 | Saturation adjustment device |
| JP2598601B2 (en) * | 1992-04-06 | 1997-04-09 | ライノタイプ−ヘル アクチエンゲゼルシャフト | Analysis and correction method of image gradation of original image |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS51150335A (en) * | 1975-06-18 | 1976-12-23 | Dainippon Screen Mfg Co Ltd | Method for correcting spectral color density signals in image scanning recording device |
| JPS55116340A (en) * | 1979-02-28 | 1980-09-06 | Fuji Photo Film Co Ltd | Method and device for processing gradation of radiation picture |
| JPS55142345A (en) * | 1979-04-23 | 1980-11-06 | Dainippon Screen Mfg Co Ltd | Masking operation method in digital color tone control |
| JPS5633700A (en) * | 1979-08-28 | 1981-04-04 | Katsuragi Sangyo Kk | Speaker box |
| JPS56128947A (en) * | 1980-03-13 | 1981-10-08 | Dainippon Screen Mfg Co Ltd | Method of setting highlight and shadow point density value of original picture to picture scanning recorder |
| JPS57208768A (en) * | 1981-06-19 | 1982-12-21 | Hitachi Ltd | Digitizing system for video signal |
| JPS5897051A (en) * | 1981-12-05 | 1983-06-09 | Dainippon Printing Co Ltd | Gradation correction device in video image plate making equipment |
| JPS58178665A (en) * | 1982-04-12 | 1983-10-19 | Canon Inc | Picture copying device |
| DE3315616A1 (en) * | 1983-04-29 | 1984-10-31 | Agfa-Gevaert Ag, 5090 Leverkusen | METHOD FOR SETTING THE COLOR SATURATION OF COLOR SIGNALS |
| JPH06101807B2 (en) * | 1984-08-10 | 1994-12-12 | ソニー株式会社 | Image signal compression circuit |
-
1985
- 1985-03-21 JP JP60056630A patent/JPH0832060B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61214893A (en) | 1986-09-24 |
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| EXPY | Cancellation because of completion of term |