JP2003270045A - Color management method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make colors reproducible in printed matter provided with color images by a more realistic method, and to provide a color management method capable of substantially reducing deviations between a print manuscript and the printed matter printed on the basis of color chips. <P>SOLUTION: The color management method is characterized in that, when color matching evaluation is performed on a print sample through the use of colorimetric values of the color chips, the color chips arranged on the basis of the relative frequency of each color in the print sample are created, and the color matching evaluation is performed on the print sample through the use of the achieved color chips in the color management method. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color management method capable of performing color reproduction on a printed matter provided with a color image by a more realistic method.

[0002]

2. Description of the Related Art In recent years, the number of printed materials handling color images has increased.
However, it is becoming more and more highly detailed. And color picture
Color measurement for image management
The color chart is used for the purpose of measuring. like this
Printed color used for color management
Various votes have been proposed. Among them I
SO126421¹⁾(Since then, JISX was established as JIS
9203 ²⁾) Is widely used internationally.
Has been done. In addition to this color chart, color management men
Proposals for original color charts used by each manufacturer
Has been done.

ISO 12642 (JISX9203)
The color charts of CMY are CMY so that a total of 928 color charts are uniform in the CMYK color space in consideration of the characteristics of the CMYK color space.
K value is specified. Further, it is divided into four subsets, and it is considered that each subset can be used individually.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention ISO 12642
The color chart of (JISX9203) is for investigating the difference in characteristics for each printing condition and for a general-purpose profile (for example, ICC profile is the device-independent color (mainly L It is a very effective color chart for creating international standard files recorded in * a * b).

However, as the printing work is specifically carried out using the color chart, there is often a problem that a discrepancy is observed between the printing original and the printed matter based on the color chart. It was happening.

The present inventors have found that such a problem of a gap between a printed original and a printed matter based on a color chart is very rough for a certain color in human visual recognition of color. It was thought that this was due to the fact that the different colors were performed very accurately, and various experiments were conducted. As a result, by correcting the conventional color chart on the assumption that human eyes visually recognize colors very coarsely for one color and very precisely for another color, It has been found that the gap between the printed matter and the printed matter can be effectively eliminated.

That is, an object of the present invention is to enable color reproduction in a printed matter provided with a color image by a more realistic method.
An object of the present invention is to provide a color management method capable of significantly reducing a deviation between a print original and a printed matter made based on a color chart.

[0008]

According to the color management method of the present invention, when color matching evaluation of a print sample is performed using colorimetric values of a color chart, the color chart arranged based on the appearance rate of each color in the print sample is used. It is characterized in that the color matching evaluation of the printed sample is performed using the color chart obtained.

The color management method of the present invention is
When performing color matching evaluation of a print sample using the colorimetric value of the above color chart, not only the color chart in which each color is evenly arranged in the color space, but also the color chart arranged based on the appearance rate of each color in the print sample It is also characterized in that the color matching evaluation is performed based on.

The color management method of the present invention is
It is also characterized in that the evaluation target reflects the appearance rate of each color in the image portion of the print sample.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the color management method of the present invention will be described below in detail with reference to the drawings. In the drawing, FIG. 1 is a graph showing a cumulative appearance rate of colors on a printed matter, showing a result of investigation of appearance frequencies of each color on a color printed matter, and FIG. 2 is a colorimetric value when a newly created color chart is printed. FIG. 6 is a graph showing an example of FIG.

In carrying out the color management method of the present invention, first, a survey sample was randomly extracted from RIP data of a color (4 color) printed matter to calculate the frequency of use. Since the print manuscript to be submitted has various data formats, resolutions, etc., low resolution (150 dpi) image data created from the data after layout was used. The data after the layout is in the form of the final printed matter on which characters, tints, and images are pasted, and reflects the actual work. Since the print size differs for each job, the size of the data (printed matter) used for the survey also differs.

In the investigation, the gradation values of each color of CMYK are divided into 16 levels, and the CMYK color space is combined (16
⁴ = 65536), the color of each pixel (unit area) is included in the block, and the usage reliabilities of the 214 samples collected at the first time are calculated.

Since four colors of CMYK inks are used in printing, there are some colors in which redundant combinations exist for printing the same color. Therefore, if there is no proper use of redundant colors depending on the situation (even if only a specific combination is used), the number of blocks used will be small.
In this study, there were 13475 (20.6% of the total) blocks in which none of the colors were used. Also,
The area of 90% of all pixels in 6.3% of the whole block,
The area of 99% of all pixels could be represented by 18.3% of the blocks.

The color in the center of the block was represented, and how the color was distributed in the L * a * b space was examined according to the frequency of use. At that time, it can be seen from the distribution of the unused blocks that many of the redundant colors are not used. Also, in this survey, bias was seen in the colors that were frequently used.

Therefore, the frequency of appearance was investigated again, and in order to eliminate the influence of seasonal variation in the collection time of the samples used in the survey, the number of samples subject to frequency of investigation was increased. Although it is not considered that all colors on the CMYK space are used uniformly, it is considered that colors are biased more than necessary if the number of samples is not sufficient. The sample used is a color (4 color) printed matter randomly extracted from what is printed for business as in the previous time. The color chart was reviewed based on this result. The survey results are shown in FIG.

Since the number of survey points was increased from 214 to 509, the appearance frequency slightly changed, and the color chart was corrected based on the appearance frequency. The correction content is the color chart 603 of the front wipe.
A total of 598 with 215 color charts reduced and 210 color charts added
The color is a new color chart. Approximately 2 of the color charts that have been replaced
Although 3 was a move to the adjacent block, the rest (about 1/8 of the whole) is considered to be the color chart replaced by this review. FIG. 2 shows an example of the colorimetric value when the newly created color chart is printed (the colorimetric value varies depending on the printing conditions). It should be noted that, in order to avoid the color from being intensively selected from the vicinity of one block, the color chart is not completely selected in the order of cumulative appearance rates but is slightly adjusted. It is considered that this replacement has eliminated the region where the density was too low in the first color chart that was prototyped.

In order to confirm the effectiveness of this color chart, the effectiveness of the color chart was confirmed using 9 sampled images different from the sample used for collecting the histogram. The investigation was conducted by the ratio of the color chart area in the extracted image. Table 1
Is the result. The color chart created in this example is not much different from the data when the color chart was created, and is considered to reflect the actual work, and is less than 1% (598/65).
536 = 0.91%), it was confirmed that 50% or more of the printed portion excluding the exposed portion of the paper was covered.

[0019]

[Table 1]

[0020]

Since the present invention is constructed as described above,
It has become possible to provide a color management method capable of performing color reproduction in a printed matter provided with a color image by a more realistic method. That is, regarding the creation (characterization) of the profile of the printed matter,
There is an international standard color chart specified in SO12642.
However, there is no standard for evaluation of color matching, because the evaluation standard may vary depending on the use environment. According to the present invention, it was possible to confirm that the evaluation using the color chart arranged based on the appearance rate of each color in the printed sample is useful in the printing site.

Further, since the present invention is configured as described above, it is possible to establish a method of easily obtaining an appropriate color chart by arranging based on the appearance rate of each color in the printed sample, and to establish a color image. It has become possible to provide a color management method capable of more efficiently performing color reproduction on a provided printed matter.

[Brief description of drawings]

FIG. 1 is a graph of a cumulative appearance rate of colors on a printed matter, showing a result of investigation of appearance frequencies of respective colors on a color printed matter.

FIG. 2 is a graph showing an example of colorimetric values when a newly created color chart is printed, showing a distribution of the color chart in a color space.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akihiro Nomura             4 Horikawa-dori Teranouchi, Kamigyo-ku, Kyoto City, Kyoto Prefecture             Made by 1 Dai Nippon Screen at No. 1 in Tenjin Kitamachi             Zou Corporation F-term (reference) 2C262 AB11 AB12 EA06 EA10 FA12                       FA13 GA02                 2G020 AA08 DA34 DA43                 5B057 AA11 CA01 CA08 CA12 CA16                       CB01 CB08 CB12 CB16 CC01                       CE17 CE18 CH08                 5C077 LL19 MM27 MP08 PP32 PP33                       PP37 PQ12 PQ19 TT02 TT06                 5C079 HB01 HB03 HB08 HB12 LB02                       MA10 MA11 NA03 PA02 PA03

Claims (3)

[Claims] 1. When a color matching evaluation of a print sample is performed using colorimetric values of a color chart, a color chart arranged based on the appearance rate of each color in the print sample is created, and the obtained color chart is used for the print sample. A color management method characterized by performing color matching evaluation of. 2. When performing color matching evaluation of a print sample using colorimetric values of a color chart, not only the color chart in which each color is evenly arranged in the color space but also the appearance rate of each color in the print sample is used. A color management method characterized by performing color matching evaluation based on arranged color charts. 3. The color management method according to claim 1, wherein the evaluation target reflects the appearance rate of each color in the image portion of the print sample.