JP2002152532A - Method for improving color reproduction and color reproduction improving system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for improving a color reproduction capable of simply dealing with the changeover aging of image equipment and a color reproduction improving system. SOLUTION: The method for improving the color reproduction comprises the steps of separating data of color reproducing characteristics of the image equipment into a fundamentally not changing ideal section and a section changing according to individual equipment or the changeover aging, and converting the color by utilizing both.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inputting and displaying a color image including a black and white image on a display or a printer.
The present invention relates to a color reproduction improving method and a color reproduction improving system for improving the reproducibility of an output device.

[0002]

2. Description of the Related Art Scanners, personal computers, color printers,
Input and output of color images from color copiers, monitors, etc.
Image devices that perform display or the like have different color reproduction characteristics from product to product of the same model as well as different models.

On the other hand, in recent years, with the rapid spread of imaging equipment,
Standards for color reproduction characteristics of imaging devices are being formulated, and there are many de facto standards. For example, I
The TU recommends the basic color reproduction characteristics of HDTV cameras ("Basic parameter values for the HDTV
standard for the studio and for international pro
gramme exchange, "Recommendation ITU-R BT.709).

In the ICC, an ICC profile format, which is a data file of color reproduction characteristics of each image device, is defined, and a framework for faithfully reproducing colors between different image devices, that is, a data file of a color management system is standardized. are doing. (International Color Consor
tium, "File Format for Color Profiles", Specificat
ion: ICC.1: 1998-09, 1998.) Hereinafter, referring to the drawings, a case will be described in which a color management system assumed by the ICC is printed on a CRT monitor by faithfully reproducing colors on a printer. This will be described using an example.

FIG. 5 is a diagram showing a configuration example of a color management system using an ICC profile. In a color management system, an image of a certain image device is converted by another image device so that colors are reproduced as faithfully as possible. Here, the former image device is a CRT monitor 11,
The latter image device will be described as a printer 13. The printer 13 and the CRT monitor 11 are connected to the personal computer 12 via a cable, and the color management system is realized as software on the personal computer 12.

FIG. 6 is a block diagram showing the operation of the color management system. Hereinafter, referring to FIG.
The operation of the color management system will be described.

[0007] RGB displayed on the CRT monitor 11
The original image 21 of the format is converted from a PCS of a color space called PCS by a program on a personal computer 12 called a color management module 20 using a source profile 24 describing the color reproduction characteristics of the CRT monitor 11.
It is converted to an image 22. Next, the PCS image 22 is converted by the color management module 20 into a printer 1 defined by CMYK using a destination profile 25 describing the color reproduction characteristics of the printer 13.
3 is converted to the output image 23. Then, the output image 23 is transmitted to the printer 13 and printed there.

Here, the PCS space is not a color space having a different color appearance for each device like RGB and CMYK, but is a device-independent color space such as CIELAB or CIEXYZ. And each imaging equipment manufacturer,
In this example, the manufacturer of the CRT monitor or printer attaches to the product a profile, which is a data file relating to the color reproduction characteristics of the image device, which enables conversion from the PCS to the device-specific color space and the reverse conversion. Therefore, it is possible to cope with a color management system without being conscious of various devices to be connected.

[0009]

The conventional image equipment has been trying to realize the improvement and stability of color reproducibility by improving the device and the manufacturing process and adjusting each product. There was a problem of an increase in costs due to limitations and adjustments.

Further, even if the color reproducibility is adjusted at the time of manufacturing,
There is a problem that the color reproducibility is deteriorated due to the aging of the image equipment itself.

[0011] The color management system includes:
Although suitable for the purpose of maintaining the color reproducibility between two different image devices, there is a problem that it is not possible to cope with the improvement of the color reproducibility of the image device itself.

Further, in the color management system, since the color of the image on the destination side is forcibly matched with the image on the source side, if the color reproducible by the former cannot be reproduced by the latter, that is, if the color gamut is different, the image is There was a problem that the color balance was lost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a color reproduction improving method and a color reproduction improving system which are simple and can cope with individual variations and aging of image equipment. And

[0014]

According to the present invention, there is provided a color reproduction improving method, comprising: a first data file relating to an ideal color reproduction characteristic of an image device for inputting, displaying or outputting an image; An image to be displayed on the image device is converted using a second data file relating to actual color reproduction characteristics of the device.

As described above, the data of the color reproduction characteristics of an image device is basically separated into an ideal portion that does not change and a portion that changes with the time of individual devices or changes over time. By converting colors, simply and in response to individual variations and changes over time of the image equipment, the colors displayed on the image equipment are converted to ideal colors, so that it is simple and easy to use. A method for improving color reproduction that can cope with individual variations of devices and changes over time can be obtained.

The color reproduction improving system of the present invention uses the color reproduction improving method of the present invention to improve the color reproducibility of an image device.

As described above, the color of the image device is converted by the color reproduction improving method which is simple and can cope with the individual variation and the aging of the image device. A color reproduction improvement system that can cope with individual variations and aging can be obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A reproduction improving method according to a first aspect of the present invention is a method for inputting, displaying or outputting an image, comprising: a first data file relating to ideal color reproduction characteristics of the image device; Using the second data file regarding the actual color reproduction characteristics of the imaging device,
An image is converted using the second data file so as to match the ideal color reproduction characteristics of the first data file, thereby improving the color reproduction characteristics of the image device.

As described above, the data of the color reproduction characteristics of an image device is basically separated into an ideal portion that does not change and a portion that changes with the time of individual devices or changes over time. By converting the colors, the colors displayed on the image device are converted to ideal colors simply and in response to individual variations and aging of the image device. This also has the effect of improving the color reproducibility of the imaging device.

According to a second aspect of the present invention, in the color reproduction improving method according to the first aspect, the first data file and the second data file are in an ICC profile format. .

As described above, the format of the color reproduction data of the image equipment is the de facto standard ICC.
By using the profile as the first and second data files, the colors displayed on the image device can be easily converted to ideal colors. This also has the effect of improving the color reproducibility of the imaging device.

According to a third aspect of the present invention, there is provided a method for improving color reproduction, comprising the steps of:
The first data file is characterized by having data relating to the primary colors of the imaging device and their ideal tone reproduction characteristics.

As described above, the colors are converted by using the data on the primary colors of the image device and the ideal tone reproduction characteristics, so that the colors displayed on the image device are out of balance due to the different color gamut. To an ideal color without producing This also has the effect of improving the color reproducibility of the imaging device.

According to a fourth aspect of the present invention, there is provided a color reproduction improving system, comprising: a first data file relating to an ideal color reproduction characteristic of an image device for inputting, displaying or outputting an image; A second data file relating to actual color reproduction characteristics of the device; and image conversion means for converting an image using the second data file so as to match an ideal color reproduction characteristic of the first data file. Wherein the first data file and the second data file are attached in advance to the image device.

As described above, the colors displayed on the image equipment are converted into ideal colors by using the first data file and the second data file attached beforehand when the product is shipped. This also has the effect of improving the color reproducibility of the imaging device.

According to a fifth aspect of the present invention, there is provided a color reproduction improving system, comprising: a first data file relating to an ideal color reproduction characteristic of an image device for inputting, displaying or outputting an image; Data file creating means for creating a second data file relating to actual color reproduction characteristics of the device; and an image using the second data file so as to match an ideal color reproduction characteristic of the first data file. And image conversion means for converting

As described above, by changing the second data file even after the product is shipped, it is possible to cope with aging.
Converts colors displayed on imaging equipment to ideal colors. Also,
This has the effect of improving the color reproducibility of the imaging device.

A color reproduction improving system according to a sixth aspect of the present invention is the color reproduction improving system according to the fourth or fifth aspect, wherein the image conversion is realized by a color management module.

As described above, the color management module installed in the OS or the like in advance can easily
Converts colors displayed on imaging equipment to ideal colors. Also,
This has the effect of improving the color reproducibility of the imaging device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the following embodiments, the monitor is described as an example of an image device. However, the present invention is not limited to this, and other image devices such as a printer and a scanner may be used.

(Embodiment 1) FIG. 1 is a configuration diagram of a device having a color reproduction improving system according to Embodiment 1 of the present invention. In FIG. 1, a liquid crystal monitor 31 is connected to a personal computer 33 by an RGB cable 32. Also,
A colorimeter 34 that outputs the CIEXYZ values of the pattern on the liquid crystal monitor 31 is connected to a personal computer 33 by a cable 35.

In the present embodiment, the device whose color reproducibility is to be improved is the liquid crystal monitor 31, and the color reproduction improving system is the software of the personal computer 33 and the colorimeter 34;
It is composed of a cable 35. In addition, the personal computer 33
An OS in which a color management module that performs color conversion using a CC profile is installed has been introduced. Most of the OSs of personal computers currently on the market are equipped with a color management module.

The personal computer 33 has a liquid crystal monitor 31.
An ICC profile 101 having RGB trichromaticity points and white points, and data on ideal color reproduction characteristics having tone reproduction characteristics calculated by the following equation is installed.

[0035]

(Equation 1)

In equation (1), x is a value obtained by dividing each input signal of RGB into a maximum value, that is, 255 in the present embodiment, and normalizing the value to a value between 0 and 1. x ′ is the luminance for the input signal, which is also a value normalized by the luminance value when the maximum input signal is input to RGB. (Equation 1) uses the tone reproduction characteristic of the IEC sRGB standard (IEC, IEC61966-2-1, 1999-10).

FIG. 2 is a graph showing the reproduction characteristic of (Equation 1).

The personal computer 33 has a liquid crystal monitor 31.
Having RGB trichromaticity point and white point, and data on actual color reproduction characteristics having measured tone reproduction characteristics
C profile 102 is installed. FIG. 3 shows an example of a tone reproduction characteristic of a liquid crystal monitor that actually exists. As shown in FIG. 2, the ideal RGB tone reproduction characteristics match in RGB, but the RGB tone reproduction characteristics do not match in an actually existing monitor as shown in FIG.

Hereinafter, the operation of the color reproduction improving system according to the embodiment of the present invention will be described.

The user periodically displays a test pattern on the liquid crystal monitor 31 with the personal computer 33, measures the tone reproduction characteristic of the liquid crystal monitor 31 with the colorimeter 34, and
The CC profile 102 is updated. In the measurement of the tone reproduction characteristic, test patterns of different gradations of RGB single colors are sequentially displayed so as to cover the entire measurement range of the colorimeter. , G
In this case, Y is used, and in B, Z is used as a luminance value. Since the tone reproduction characteristic itself is normalized from 0 to 1, it is not necessary to use the Y value as the luminance value. Further, for R and B, X and Z values can be measured more accurately than Y values, so X and Z are used respectively.

During normal use, the color management module of the personal computer 33 uses the ICC profile 101 and the ICC profile 102 to
The color of each pixel of the image to be displayed is converted and displayed.

Hereinafter, the conversion method will be described with reference to FIG.

FIG. 4 is a PAD diagram of a procedure for converting colors. First, in the color management module of the personal computer 33, the RGB values of the color of the pixel to be displayed are
Normalize to a value from 0 to 1. In the present embodiment, the value of 0 to 255, which is the input value of RGB of the current general monitor, is divided by 255 to normalize the value to 0 to 1 (S10).

Next, the normalized RGB values are converted into luminance values normalized from 0 to 1 by using the tone reproduction characteristics as shown in FIG. 3 of the ICC profile 101 (S1).
1). Next, this luminance value is used for the ICC profile 102
Are converted into RGB values normalized from 0 to 1 (S12). This is obtained by reversing the tone reproduction characteristic as shown in FIG. 3 for each of RGB. In addition, ICC
Since the trichromaticity points of the profile 101 and the ICC profile 102 match, the RGB values may be converted independently.

Next, the calculated normalized RGB values are again converted into values from 0 to 255 which are the inputs of the ordinary liquid crystal monitor 31 (S13), and an image is displayed on the liquid crystal monitor 31 with the calculated pixel values. It is displayed (S14).

As described above, in the color reproduction improving system according to the present embodiment, the ICC profile 1 relating to the actual color reproduction characteristics of the liquid crystal monitor 31 is periodically measured by the colorimeter.
02 and updated IC with ideal color reproduction characteristics
By using the C profile 101, an image close to ideal color reproduction characteristics is displayed on the liquid crystal monitor 31. Therefore, a color reproduction improvement method that is simple and can cope with device variations and aging changes has been realized, and a color reproduction improvement system that is simple and can also cope with device variations and aging changes has been realized. I have.

As the ideal color reproduction characteristics, since the three chromaticity points of the liquid crystal monitor 31 and the ideal tone reproduction characteristics are used, there is no difference in the color gamut due to the difference in the chromaticity points. Thus, the color balance of the image is not lost, thereby realizing a simple color reproduction improving method.

Further, since color conversion is performed by a color management module installed in the OS in advance, it is not necessary to add a special conversion program, and a color reproduction improving system can be realized more easily.

In the present embodiment, the method of improving color reproduction is realized as software of a personal computer. However, the present invention is not limited to this. For example, a monitor may be provided with a microprocessor, a memory and an interface of a colorimeter.
Realizing a color reproduction improvement method on the microprocessor,
Thus, a color reproduction improving system may be configured.

In the present embodiment, the monitor is used as an example for explanation, so the primary colors are RGB. However, the present invention is not limited to this. For example, CMYK is used for a printer. Further, when the number of primary colors is 4 or more and less than 3, for example, the number may be 1 as in a black and white monitor.

In the present embodiment, the data relating to the actual color reproduction characteristics of the monitor is measured by the colorimeter. However, the present invention is not limited to this. Measure the actual color reproduction characteristics with a software tool that adjusts the color reproduction characteristics with
May be created. Further, the tone reproduction characteristic may be measured only with Y using a luminance meter instead of the colorimeter. If the temporal change of the target imaging device is small, the colorimeter may be omitted and an ICC profile created by measurement at the time of product shipment may be attached as a data file relating to actual color reproduction characteristics. .

[0052]

As described above, according to the present invention, the color reproducibility of a device for displaying and outputting a color image including a black and white image can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a device having a color reproduction improvement system according to an embodiment of the present invention.

FIG. 2 is a view showing an ideal tone reproduction characteristic of an ICC profile which is a first data file of the color reproduction improving system according to the embodiment of the present invention;

FIG. 3 is a diagram showing tone reproduction characteristics of an actually existing liquid crystal monitor of an ICC profile which is a second data file of the color reproduction improvement system according to the embodiment of the present invention;

FIG. 4 is a PAD diagram of a procedure for converting colors of the color reproduction improving system according to the embodiment of the present invention;

FIG. 5 is a diagram illustrating a configuration example of a color management system using an ICC profile;

FIG. 6 is a block diagram of the operation of the color management system.

[Explanation of symbols]

 11, 31 monitor 12, 33 personal computer 13 printer 32, 35 cable 34 colorimeter 101 ICC profile 102 ICC profile

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Katsuji Aoki 3-10-1, Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa Prefecture Inside Matsushita Giken Co., Ltd. (72) Katsuhiro Kanamori 3-chome, Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa No. 10 No. 1 Matsushita Giken Co., Ltd. F term (reference) 5B057 CA01 CA08 CA12 CB01 CB08 CB12 CC01 CE17 CH18 DB02 DB06 DB09 5C077 LL17 LL19 NP07 PP31 PP32 PP37 PP66 PQ22 SS01 SS06 TT02 TT06 5C079 HB01 MA11 NA21 NA27 PA03 PA05

Claims (6)

[Claims] 1. An image device for inputting, displaying, or outputting an image, wherein: a first data file relating to ideal color reproduction characteristics of the image device; and a second data file relating to actual color reproduction characteristics of the image device. And converting the image using the second data file so as to match the ideal color reproduction characteristic of the first data file, thereby improving the color reproduction characteristic of the image device. Characteristic color reproduction improvement method. 2. The method according to claim 1, wherein the first data file and the second data file are in an ICC profile format. 3. The color reproduction improving method according to claim 1, wherein the first data file has data on the primary colors of the image equipment and their ideal tone reproduction characteristics. 4. An image device for inputting, displaying, or outputting an image, wherein: a first data file relating to ideal color reproduction characteristics of the image device; and a second data file relating to actual color reproduction characteristics of the image device. And image conversion means for converting an image using the second data file so as to match an ideal color reproduction characteristic of the first data file. 2. A color reproduction improving system using a data file of which the data file is attached to an image device in advance. 5. An image device for inputting, displaying or outputting an image, wherein a first data file relating to ideal color reproduction characteristics of the image device and a second data file relating to actual color reproduction characteristics of the image device. And an image conversion means for converting an image using the second data file so as to match an ideal color reproduction characteristic of the first data file. Color reproduction improvement system. 6. The image processing apparatus according to claim 4, wherein the conversion of the image is realized by a color management module.
The described color reproduction improvement system.