JP2004128538A - Inspection system, inspection method, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection system enabling a user to easily confirm the difference between RGB data and CMYK data. <P>SOLUTION: The inspection system 1 applies Lab transformation to each of the RGB image data when received DTP data are confirmed and the CMYK image data obtained by applying RIP processing to the DIP data. When the difference ΔE between pixels obtained by applying the Lab transformation to them exceeds a set value, a display apparatus displays the corresponding pixel. It can be confirmed that the displayed area indicates the difference between the RGB data and the CMYK data. <P>COPYRIGHT: (C)2004,JPO

Description

【００４０】
尚、式（３）において、
ΔＬ＝Ｌ_１−Ｌ_２
Δａ＝ａ_１−ａ_２　　　　　　　　　　……（４）
Δｂ＝ｂ_１−ｂ_２
である。
【００４１】
ΔＥの許容値を１０．０に設定すると、算出されるΔＥが１０．０を超える画素が、Ｌａｂ差分画像１５として表示装置７に表示される（ステップ３０８）。即ち、図２に表示されるＬａｂ差分画像１５の領域５１は、ΔＥが許容値１０．０を越えた領域である。作業者は、表示装置７に表示されるＬａｂ差分画像１５により、ＲＧＢデータとＣＭＹＫデータとの差異を確認することができる。
【００４２】
また、ＲＩＰ処理により、コード番号と書体名等で指示された文字（フォント）データを、ＲＩＰ装置に保存、もしくはＤＴＰデータ内に保存してあるフォントデータにより、文字コードからビットマップデータに置き換える際、保存されているフォントデータの不備等（例えば該当する書体が保存されていない等）が原因で、異なる書体（明朝体、ゴシック体）で再現される等、ＤＴＰ制作側が意図したイメージと異なる文字（図形）になることがある。この違いを本装置でチェックすることができる。
【００４３】
このように、本実施の形態によれば、入稿されるＤＴＰデータの完成イメージをＤＴＰ制作側が確認した時のＲＧＢ表示データと、ＲＩＰ処理後のＣＭＹＫデータとを、それぞれＬａｂ変換して、同じＬａｂ色空間上で比較し、差異が許容値を超える領域を表示装置に表示するので、簡単にＲＧＢデータとＣＭＹＫデータとの差異を確認することができる。
【００４４】
また、従来の出力物とモニタ表示を目視して差異を確認する方法に比べると、作業負荷が少なく、また、差異を正確にチェックできる効果がある。
【００４５】
【発明の効果】
以上、詳細に説明したように本発明によれば、簡単にＲＧＢデータとＣＭＹＫデータとの差異を確認することのできる検査システムを提供することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る検査システム１の構成を示す図
【図２】表示装置７に表示される画像を示す図
【図３】Ｌａｂ対応テーブル作成の手順を示す図
【図４】検査システム１のフローチャート
【符号の説明】
１・・・　検査システム
２・・・　ＤＴＰ制作側
３・・・　演算装置
５・・・　記憶装置
７・・・　表示装置
９・・・　モニタ表示
１１・・・　ＲＧＢ画像
１３・・・　ＣＭＹＫ画像
１５・・・　Ｌａｂ差分画像
１７・・・　ＲＧＢ画像データ
１９・・・　ＣＭＹＫ画像データ
２１・・・　ＤＴＰデータ
２３・・・　ＲＩＰ処理
２５・・・　Ｌａｂ変換ａ、ｂ
２７・・・　ΔＥの算出
２９・・・　Ｌａｂ対応テーブルａ、ｂの作成
３１・・・　Ｌａｂ対応テーブルａ、ｂ
３３・・・　ΔＥ
４１、４３、４５、４７、４９、５１・・・　領域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inspection system for confirming a difference between RGB data for monitor display of DTP data and CMYK data for printing.
[0002]
[Prior art]
In the DTP data plate making process, character typesetting, and the like, an image on which the DTP data is displayed on a monitor may not match an output result obtained by converting the DTP data for printing. Conventionally, an operator visually confirms a difference between a printout and a monitor display.
[0003]
Further, for example, CMYK data for printing is converted into data such as TIFF and compared.
[0004]
[Problems to be solved by the invention]
However, the task of visually confirming the difference between the printed output and the monitor display is a burden on the operator, is inefficient, and sometimes the difference cannot be confirmed. In addition, in order to accurately confirm the difference, it is necessary to install the same dedicated device for data conversion on the DTP production side and on the printing data conversion department, which is costly and inefficient.
[0005]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an inspection system capable of easily confirming a difference between RGB data and CMYK data.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an inspection system for confirming a difference between RGB data and CMYK data, comprising: means for converting RGB data into CMYK data; Lab conversion means for performing Lab conversion on each of CMYK data, and display means for calculating a difference between the Lab-converted data and displaying an area corresponding to a difference exceeding a set value among the differences. Is an inspection system.
[0007]
The RGB data is data expressing the color tone by adding and mixing three primary colors of light of R (Red Red), G (Green Green), and B (Blue Blue), and is used for monitors, scanners, color televisions, and the like. I have.
The CMYK data is data expressing the color tone by subtractively mixing the primary colors of C (Cyan blue), M (Magenta red), Y (Yellow yellow), and B (Black black), and is used for color printing and the like. I have.
The Lab conversion is to convert RGB data and CMYK data into data in a Lab color space using respective Lab correspondence tables, and color tones can be compared. The Lab color space was proposed in 1976 by the International Commission on Illumination CIE (Commission Internationale de I'Eclairage), where L is lightness (brightness), a is color coordinates from red to green, and b is blue to yellow. Represents the color coordinates of. The Lab color space has a wide color gamut and a small difference in color tone between systems.
The Lab correspondence table is a CMYK image Lab correspondence table created by performing Lab conversion and interpolation processing of a CMYK chart image and an RGB image acquired by displaying a CMYK chart image on a screen by performing Lab conversion and interpolation processing. It is a Lab correspondence table for RGB images to be created.
The CMYK chart image is, for example, a standard chart (928 colors) of CMYK data determined by the ISO standard. The data of each color is subjected to Lab conversion, the data is interpolated according to the monitor or the output device, and a CMYK image Lab correspondence table is created.
Further, the CMYK chart image is displayed on the screen to obtain RGB image data, the data of each color is subjected to Lab conversion, and the data is interpolated in accordance with a monitor or an output device to create an RGB image Lab correspondence table.
Further, the RGB data is converted to CMYK data by performing a RIP process. RIP (Raster Image Processor) processing is processing for rasterizing (developing) vector data described by a mathematical expression into a bitmap (raster image). This is data processing when outputting to an output device such as an image setter or a printing device.
The inspection system of the first invention converts RGB data into CMYK data, performs Lab conversion on each of the RGB data and CMYK data, and displays an area corresponding to a difference exceeding a set value among the differences.
[0008]
A second invention is an inspection system for confirming a difference between RGB data and CMYK data. The inspection system acquires a CMYK chart image, displays the screen and acquires an RGB image, and performs Lab conversion of the CMYK image. , A Lab correspondence table, and a means for converting the RGB image into a Lab to create a Lab correspondence table.
[0009]
The inspection system of the second invention acquires a CMYK chart image, displays it on a screen, acquires an RGB image, performs Lab conversion on each of the CMYK image and the RGB image, and creates a respective Lab correspondence table.
[0010]
According to a third aspect, in an inspection system for confirming a difference between RGB data and CMYK data, a step of converting RGB data into CMYK data, and a Lab conversion step of performing Lab conversion on each of the RGB data and the CMYK data And a display step of calculating a difference between the Lab-converted data and displaying an area corresponding to a difference exceeding a set value among the differences.
[0011]
An inspection method according to a third invention is a method of the inspection system according to the first invention.
[0012]
According to a fourth aspect of the present invention, in the inspection system for confirming the difference between the RGB data and the CMYK data, a step of acquiring a CMYK chart image, displaying it on a screen and acquiring an RGB image, converting the CMYK image into a Lab, An inspection method comprising: a step of creating a correspondence table; and a step of converting the RGB image to Lab to create a Lab correspondence table.
[0013]
The inspection method of the fourth invention is a method of the inspection system of the second invention.
[0014]
A fifth invention is a program for realizing the inspection system according to the first or fourth aspect.
[0015]
A program according to a fifth invention causes the inspection system according to claim 1 or 4 to function, and the program can be distributed via a network.
[0016]
A sixth invention is a recording medium recording a program for realizing the inspection system according to the first or fourth aspect.
[0017]
A recording medium according to a sixth aspect of the present invention stores a program for causing the inspection system according to claim 1 or 4 to function. The recording medium can be distributed, and the program is distributed via a network. You can also.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of an inspection system 1 according to an embodiment of the present invention. The inspection system 1 includes a calculation device 3, a storage device 5, and a display device 7. The inspection system 1 receives the DTP data 21 created by the DTP production side 2 and the RGB image data 17 on the screen.
[0019]
Although details will be described later, the arithmetic unit 3 converts the acquired DTP data 21 into CMYK image data 19 by performing RIP processing 23. The RIP processing 23 may be performed by another device and the result may be obtained as a CMYK image. In addition, respective Lab conversion tables a and b for RGB data and CMYK data are created. Further, the obtained RGB image data 17 and the converted CMYK image data 19 are subjected to Lab conversion using the Lab conversion table. Further, a difference ΔE33 between the Lab-converted RGB image data 17 and the converted CMYK image data 19 is calculated, and an area corresponding to ΔE exceeding a set value (for example, ΔE is 10) is displayed on the display device.
[0020]
The storage device 5 stores the acquired RGB image data 17. Also, the CMYK image data 19 obtained by performing the RIP processing 23 on the DTP data 21 is stored. Further, the calculated difference ΔE33 is stored. In addition, the “Lab conversion tables a, b” 31 for the RGB data and the CMYK data to be created are stored.
[0021]
The display device 7 displays the RGB image 11, the CMYK image 13, the Lab difference image 15 (area image exceeding the set value among ΔE) and the like in the processing steps of the inspection system 1.
[0022]
FIG. 2 shows the images displayed on the display device 7 of FIG. 1 in detail. For example, the area 41 shown in the RGB image 11 and the area 45 shown in the CMYK image 13 are not displayed on the Lab difference image 15. That is, it can be seen that the difference ΔE33 in the Lab conversion between the region 41 and the region 45 is equal to or smaller than the set value. In addition, the area 47 of the CMYK image 13 is displayed as the area 51 on the Lab difference image 15 because the difference ΔE33 exceeds the set value when compared with the corresponding area of the RGB image 11. That is, the operator can recognize the area displayed in the Lab difference image 15 as the difference between the screen display and the time of printing.
[0023]
Next, a processing procedure of the inspection system 1 according to the present embodiment will be described with reference to FIGS.
[0024]
FIG. 3 is a diagram showing a procedure in which the arithmetic unit 3 creates the “Lab correspondence tables a, b” 31. The Lab correspondence table a is a conversion table used when converting CMYK data into Lab data, and is obtained by performing data interpolation processing according to a display device or a printing device to be used. The Lab correspondence table b is a conversion table used when converting RGB data into Lab data, and is obtained by performing data interpolation processing according to a display device or a printing device to be used.
[0025]
First, the inspection system 1 selects, for example, a standard chart (928 colors) of CMYK data determined by the ISO standard (Step 201).
[0026]
Next, Lab conversion processing is performed for each color of the chart (step 202). Furthermore, not only differences in models and manufacturers of output monitors, imagesetters and the like, but also differences in electron beam balance occur in the same model, so that interpolation processing is performed (step 203). That is, a Lab correspondence table a indicating the correspondence between each color and the Lab value is created (Step 204). The Lab correspondence table a is stored in the storage device 5.
[0027]
Therefore, assuming that a certain color of the CMYK chart is represented by CMYK data (c, m, y, k), the Lab value is obtained by dividing the elements L, a, and b as functions of c, m, y, and k, respectively, It is expressed as in equation (1).
_{(L, a, b) =} (f L 1 (c, m, y, k), f a1 (c, m, y, k), f b1 (c, m, y, k)) ...... (1 )
[0028]
On the other hand, a standard chart (928 colors) of the selected CMYK data is displayed on a monitor to obtain an RGB image (step 205). That is, the RGB values when each color of the CMYK chart is displayed on the monitor are acquired. Further, each RGB value is subjected to Lab conversion (step 206), and a unique interpolation process such as monitoring is performed (step 207), and a Lab correspondence table b indicating the correspondence between each RGB value and Lab value is created (step 206). 208). The Lab correspondence table b is stored in the storage device 5.
[0029]
In the creation of the Lab correspondence table b, if a certain color is represented by RGB data (r, g, b), the Lab value is obtained by defining the elements L, a, b as functions of r, g, b, respectively. It is expressed as in the following equation (2).
(L, a, b) = (f _{L 2} (r, g, b), f _a2 (r, g, b), f _b2 (r, g, b)) (2)
[0030]
The “Lab correspondence tables a, b” 31 created as described above are stored in the storage device 5 of the inspection system 1.
[0031]
Next, FIG. 4 is a flowchart of color difference detection between the RGB image submitted to the inspection system 1 and the CMYK image. This will be described with reference to FIGS.
[0032]
First, in FIG. 1, the DTP production side 2 creates the DTP data 21 while displaying on the monitor 9. Further, the created DTP data 21 is stored as an RGB image displayed on a monitor (step 101 in FIG. 1), and is submitted to the inspection system 1 of the print data conversion section together with the created DTP data 21 (FIG. 1 step 102). The submission may be performed on a network such as the Internet or via a storage medium.
[0033]
The storage device 5 of the inspection system 1 obtains a completed image intended by the DTP production side 2 as RGB image data 17 (Step 301).
[0034]
The arithmetic unit 3 performs data processing when outputting the submitted DTP data 21 to an output device such as an image setter or a printing device, that is, RIP for rasterizing vector data described by a mathematical expression into a bitmap (raster image). The process 23 is performed to obtain the CMYK image data 19 (step 302).
[0035]
The CMYK image data 19 is recorded in the storage device 5 (Step 106 in FIG. 1). Next, the CMYK image data 19 is subjected to Lab conversion using the Lab correspondence table a (step 304).
[0036]
On the other hand, the RGB image data 17 submitted to the inspection system 1 is subjected to Lab conversion using the Lab correspondence table b (step 306).
[0037]
That is, the input RGB image data 17 and the data obtained by converting the DTP data 21 into the CMYK image data 19 are respectively subjected to Lab conversion. Next, the color difference (ΔE) calculation 27 is performed for each of the Lab-transformed pixels (step 307).
[0038]
Color difference Delta] E ₁₂ between the two Lab values in Lab color space _{(L 1, a 1, b} 1) and _{(L 2,} a 2, _{b 2)} is obtained by the equation (3).
[0039]
(Equation 1)

[0040]
Note that in equation (3),
ΔL = L ₁ −L ₂
Δa = a ₁ −a ₂ (4)
Δb = b ₁ −b ₂
It is.
[0041]
When the allowable value of ΔE is set to 10.0, the pixel whose calculated ΔE exceeds 10.0 is displayed on the display device 7 as the Lab difference image 15 (Step 308). That is, the region 51 of the Lab difference image 15 displayed in FIG. 2 is a region where ΔE exceeds the allowable value 10.0. The operator can confirm the difference between the RGB data and the CMYK data from the Lab difference image 15 displayed on the display device 7.
[0042]
Also, when the character (font) data designated by the code number and the typeface name is stored in the RIP device by the RIP process, or replaced from the character code to the bitmap data by the font data stored in the DTP data. The image is different from the image intended by the DTP production side, such as being reproduced in a different typeface (Mincho style, Gothic style) due to inadequate stored font data (for example, the corresponding typeface is not stored). May be characters (graphics). This difference can be checked with the present device.
[0043]
As described above, according to the present embodiment, the RGB display data when the DTP production side confirms the completed image of the DTP data to be submitted and the CMYK data after the RIP processing are Lab-converted into the same, respectively. Since the comparison is made in the Lab color space and the area where the difference exceeds the allowable value is displayed on the display device, the difference between the RGB data and the CMYK data can be easily confirmed.
[0044]
Further, compared with the conventional method of visually confirming the difference between the output product and the monitor display, there is an effect that the work load is small and the difference can be accurately checked.
[0045]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide an inspection system capable of easily confirming a difference between RGB data and CMYK data.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an inspection system 1 according to an embodiment of the present invention. FIG. 2 is a diagram showing an image displayed on a display device 7. FIG. 3 is a diagram showing a procedure for creating a Lab correspondence table. 4) Flowchart of inspection system 1 [Description of reference numerals]
DESCRIPTION OF SYMBOLS 1 ... Inspection system 2 ... DTP production side 3 ... Calculation device 5 ... Storage device 7 ... Display device 9 ... Monitor display 11 ... RGB image 13 ... CMYK image 15 ... Lab difference image 17 ... RGB image data 19 ... CMYK image data 21 ... DTP data 23 ... RIP processing 25 ... Lab conversion a, b
27 ... Calculation of ΔE 29 ... Creation of Lab correspondence tables a and b 31 ... Lab correspondence tables a and b
33 ... ΔE
41, 43, 45, 47, 49, 51 ... region

Claims (10)

An inspection system for confirming a difference between RGB data and CMYK data,
Means for converting RGB data into CMYK data;
Lab conversion means for performing Lab conversion on each of the RGB data and the CMYK data,
Display means for calculating a difference between the Lab-converted data and displaying an area corresponding to a difference exceeding a set value among the differences;
An inspection system comprising: The inspection system according to claim 1, wherein the Lab conversion unit converts the RGB data and the CMYK data using respective Lab correspondence tables. The Lab correspondence table is:
A CMYK image Lab correspondence table created by performing Lab conversion and interpolation processing on the CMYK chart image,
3. The inspection system according to claim 2, wherein the inspection system is an RGB image Lab correspondence table created by performing Lab conversion and interpolation processing on an RGB image obtained by displaying the CMYK chart image on a screen. An inspection system for confirming a difference between RGB data and CMYK data, a unit for acquiring a CMYK chart image, displaying it on a screen, and acquiring an RGB image,
Means for performing Lab conversion of the CMYK image and creating a Lab correspondence table;
Means for converting the RGB image into a Lab to create a Lab correspondence table;
An inspection system comprising: In an inspection system for confirming a difference between RGB data and CMYK data,
Converting RGB data to CMYK data;
A Lab conversion step of performing Lab conversion on each of the RGB data and the CMYK data;
A display step of calculating a difference between the Lab-converted data and displaying an area corresponding to a difference exceeding a set value among the differences;
An inspection method, comprising: The inspection method according to claim 5, wherein in the Lab conversion step, the RGB data and the CMYK data are converted using respective Lab correspondence tables. The Lab correspondence table is:
A CMYK image Lab correspondence table created by performing Lab conversion and interpolation processing on the CMYK chart image,
7. The inspection method according to claim 6, wherein the inspection method is an RGB image Lab correspondence table created by performing Lab conversion and interpolation processing on an RGB image obtained by displaying the CMYK chart image on a screen. In an inspection system for confirming a difference between RGB data and CMYK data,
A step of acquiring a CMYK chart image, displaying it on a screen, and acquiring an RGB image;
Converting the CMYK image into a Lab to create a Lab correspondence table;
Converting the RGB image into a Lab to create a Lab correspondence table;
An inspection method, comprising: A program for realizing the inspection system according to claim 1. A recording medium on which a program for realizing the inspection system according to claim 1 or 4 is recorded.

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