Color correction system of imaging apparatus

What is claimed is:

1. A color correction system for an imaging apparatus, comprising:

at least one of an imaging apparatus for detecting the color of at least one point of an object and an imaging apparatus for outputting image information;

conversion means for converting the color information of an input-output signal of said imaging apparatus on the basis of the color conversion characteristic of said imaging apparatus;

reference data means for providing reference data, the reference data being common to a plurality of imaging apparatuses;

detecting means for detecting at least one value among the color information of an input-output signal of said imaging apparatus, at least one adjustment status set value of said imaging apparatus, and at least one status value indicating at least the variation per year of said color conversion characteristic and the use environment of said imaging apparatus; and

control means for controlling the color information of the input-output signal of said imaging apparatus by controlling the color conversion characteristic of said conversion means on the basis of an output signal of said detection means and said reference data provided by said reference data means.

2. A color correction system according to claim 1, wherein the color conversion characteristic of said imaging apparatus can be rewritten according to said imaging apparatus.

3. A color correction system according to claim 1, wherein said reference data means includes storage means for storing a reference value of the non-luminous object color of said object; and

wherein said control means controls the color information on the basis of said stored reference value.

4. A color correction system according to claim 3, wherein the reference value stored in said storage means is a reference value for the light source color for irradiating said object and the non-luminous object color of said object.

5. A color correction system according to claim 1, further comprising:

detection means only for the use environment of said imaging apparatus.

6. A color correction system according to claim 5, wherein said detection means can be used as detection means for the use environment of said imaging apparatus.

7. A color correction system according to claim 1, further comprising:

input means for inputting the use environment of said imaging apparatus.

8. A color correction system according to claim 3, wherein the reference value stored in said storage means includes a numerical parameter of the color standard.

9. A color correction system according to claim 8, further comprising:

means for interpolating the numerical value of the numerical parameter stored in said storage means.

10. A color correction system according to claim 1, further comprising:

means for generating a warning signal for inputting an image signal which is beyond the color reproduction range of said imaging apparatus into said conversion means or for outputting it from said image output means.

11. A color correction system according to claim 1, wherein said conversion means converts the color information included in an input or output signal to said conversion means so as to compress or expand in order to use the color reproduction range of said imaging apparatus effectively.

12. A color correction system according to claim 3, wherein an input unit of said control means has storage means for storing the reference value for said non-luminous object color and said detection means is detection means for detecting the image color to be outputted to said image output means.

13. A color correction system according to claim 1, wherein the means for outputting said image information is a display.

14. A color correction system according to claim 1, wherein the means for outputting said image information is a print device.

15. A color correction system according to claim 1, wherein the means for outputting said image information can be replaced with another image output device.

16. A color correction system according to claim 4, wherein an input unit of said control means has storage means for storing the reference value for said light source color and non-luminous object color and said detection means is detection means for detecting the image color to be outputted to said image output means.

17. A color correction system according to claim 16, wherein a color fetching device is used as said detection means.

18. A color correction system according to claim 16, wherein said detection means can be replaced with another image input device.

19. A system comprising:

a plurality of color correction systems each according to claim 3, said plurality of color correction systems being used for respective objects; and

signal transmission means for connecting said plurality of color correction systems to each other.

20. A system according to claim 19, wherein at least one of said plurality of color correction systems is an order reception terminal for nonstore retailing.

21. A system according to claim 19, wherein at least one of said plurality of color correction systems is a business support terminal and at least one is a production management terminal so as to realize quick production to order.

22. A system according to claim 19, wherein at least one of said plurality of color correction systems detects image data of non-luminous object color of an object.

23. A color correction system according to claim 3, wherein said control means controls said conversion means so that the component of non-luminous object color included in the color reproduction area of said color correction system is reproduced faithfully in the color space.

24. A color correction system according to claim 1, wherein said conversion means having the predetermined conversion characteristic has at least one of a ROM storing the conversion parameter and an LSI having the conversion function.

25. A color correction system according to claim 2, wherein said detection means detects both the status value indicating the use environment of at least one said imaging apparatus and the color information outputted by an imaging apparatus which outputs said image information.

26. A color correction system according to claim 1, wherein at least one of a signal inputted into said converter and a signal outputted from said converter is a signal corresponding to an optical parameter for which the image color can be determined quantitatively on the basis of the visibility.

27. A color correction system according to claim 1, wherein at least one of a signal inputted into said color correction system and a signal outputted from said color correction system is a signal corresponding to an optical parameter for which the image color can be determined quantitatively on the basis of the visibility.

28. A color correction system according to claim 26, wherein a signal corresponding to the CIE XYZ tristimulus values is used as said optical parameter for which the image color can be determined quantitatively on the basis of the visibility.

29. A color correction system according to claim 26, wherein a signal corresponding to the color defining value in the uniform color space is used as said optical parameter for which the image color can be determined quantitatively on the basis of the visibility.

30. A color correction system according to claim 2, wherein as at least one of a signal which is inputted into said converter and a signal which is outputted from said converter, a signal to which at least one of information on whether the displayed image is a still picture or moving picture, information on a pixel arrangement constituting the displayed image, and information on the constitution of the displayed image is added as added information is used in addition to an image signal.

31. A color correction system according to claim 2, wherein as at least one of a signal which is inputted into said converter and a signal which is outputted from said converter, a signal to which the information for designating an imaging apparatus which is suited to handling said image is added is used in addition to an image signal.

32. A system comprising:

a plurality of color corrections systems each according to claim 1, said plurality of color correction systems being used for respective objects; and

signal transmission means for connecting said plurality of color correction systems to each other.

33. A color correction system according to claim 1, wherein at least one said imaging apparatus comprises an imaging apparatus for detecting the color of at least one point and an imaging apparatus for outputting said image information and said conversion means further comprising:

first conversion means for converting the color information of an output signal of said detecting imaging apparatus; and

second conversion means for converting the color information of a signal to be inputted into said outputting imaging apparatus.

34. A color correction system according to claim 2, further comprising:

signal processing means containing said conversion means;

wherein said signal processing means has said control means for correcting the profile data which decides the color conversion characteristic in said conversion means contained in said signal processing means by detection output of said detection means.

35. A color correction system according to claim 2, further comprising:

signal processing means for processing an input signal into said imaging apparatus for outputting image information;

wherein said signal processing means has said control means for correcting the profile data which decides the color conversion characteristic in said conversion means by detection output of said detection means.

36. A color correction system according to claim 1, further comprising:

display control means for displaying a background image for indicating an actual use environment which is supposed for said displayed image on the background of the displayed image by said outputting imaging apparatus.

37. A color correction system according to claim 2, further comprising:

at least one of print control means for printing a background image for indicating an actual use environment which is supposed for said printed image on the background of the printed image by said imaging apparatus for outputting image information and print control means for selecting a printing paper having a background image for indicating an actual use environment which is supposed for a printed image as a base and printing said printed image.

38. A color correction system according to claim 30, wherein background image information for indicating the actual use environment of said displayed image which is to be displayed on the background of the displayed image of said image outputting means is also added to said signal to which said added information is added and which is used as at least one said signal.

39. A color correction system according to claim 2, wherein said conversion means consists of an integrated circuit containing a non-linear conversion circuit which can exercise electronic control.

40. A color correction system according to claim 2, wherein primary color signals of CMY or CMYK (cyan, magenta, yellow, black) are used as a signal to be inputted into said conversion means.

41. A color correction system for an imaging apparatus, comprising:

at least one imaging apparatus selected from an imaging apparatus for detecting the color of at least one point of an object and an imaging apparatus for outputting image information;

first conversion means for converting the color information of an input or output signal of said at least one imaging apparatus on the basis of at least one value among at least one adjustment status set value of said at least one imaging apparatus and at least one status value indicating the use environment of said at least one imaging apparatus;

second conversion means for converting the color information of said input or output signal on the basis of at least one of the type of a signal to be inputted or outputted into or from said first conversion means and a white balance setting status; and

signal processing means for controlling said second conversion means.

42. A color correction system according to claim 41, wherein said first conversion means converts said color information furthermore on the basis of the non-linear conversion characteristic of said at least one imaging apparatus.

43. A color correction system for an imaging apparatus, comprising:

a business support terminal;

a production management terminal; and

a transmission path connecting the business support terminal to the production management terminal;

wherein the business support terminal includes:

an imaging apparatus for outputting image information;

inputting means for inputting color information of at least one point of an object to be ordered;

receiving means for receiving color information from the production management terminal through the transmission path;

reference data means for providing reference data, the reference data being common to a plurality of imaging apparatuses;

conversion means for converting at least one of the inputted color information and the received color information based on a color conversion characteristic of the imaging apparatus and the reference data provided by the reference data means;

outputting means for outputting the converted color information through the imaging apparatus; and

sending means for sending the inputted color information and required color information related to the object to be ordered to the production management terminal through the transmission path; and

wherein the production management terminal includes:

storage means for storing color data for providing color information in accordance with the object to be ordered;

receiving means for receiving the inputted color information from the business support terminal through the transmission path;

generating means for generating the required color information by use of the color data stored in the storage means; and

sending means for sending the generated required color information to the business support terminal through the transmission path.

44. A color correction system for an imaging apparatus, comprising:

at least one of an imaging apparatus for detecting a color of at least one point of an object and an imaging apparatus for outputting image information;

conversion means for converting color information of an input signal of the at least one imaging apparatus to an output signal based on a color conversion characteristic of the at least one imaging apparatus, the conversion means including at least one of

an exchangeable portable ROM, or a disk storage device, for storing a conversion parameter of the color conversion characteristic, and

an exchangeable portable LSI having a conversion function of the color conversion characteristic;

reference data means for providing reference data, the reference data being common to a plurality of imaging apparatuses;

detection means for detecting at least one value among an adjustment status set value of the at least one imaging apparatus, and a status value indicating time variation of the color conversion characteristic of the at least one imaging apparatus; and

control means for controlling the color information of the input/output signal of the at least one imaging apparatus by controlling the color information in the conversion means based on the at least one value detected by the detection means and the reference data provided by the reference data means.

45. A color correction system for an imaging apparatus, comprising:

at least one of an imaging apparatus for detecting a color of at least one point of an object, and an imaging apparatus for outputting image information;

built-in conversion means for converting color information of an input signal of the at least one imaging apparatus to an output signal based on profile data of a color conversion characteristic of the at least one imaging apparatus;

reference data means for providing reference data, the reference data being common to a plurality of imaging apparatuses;

detection means for detecting at least one value among an adjustment status set value of the at least one imaging apparatus, and a status value indicating time variation of the color conversion characteristic of the at least one imaging apparatus; and

control means for controlling the color information of the input/output signal of the at least one imaging apparatus by controlling the color information in the conversion means based on the at least one value detected by the detection means and the reference data provided by the reference data means.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a color correction system having a converter which can correct image colors handled by an imaging apparatus and a color reproduction system which can realize faithful color reproduction and ensure high reliability of transfer color data among light source colors such as displayed colors and non-luminous object colors such as reflected colors and transmitted colors.

2. Description of the Prior Art

As order receiving systems for various kinds of products have been computerized recently, opportunities of deciding colors of products by using image data on a monitor display screen have been increased. Therefore, development of an imaging apparatus and system which can faithfully transmit and reproduce displayed colors on the monitor display screen is expected.

As a method for faithfully reproducing displayed colors on the monitor display screen, a method for converting input signals equivalent to the light source colors displayed on the monitor display screen to color parameters (tristimulus values determined by CIE (Commission Internationale de l'Eclairage)) of the non-luminous object colors which are the colors of a product is known. For example, the mutual conversion method disclosed in Japanese Patent Application Laid-Open No. 2-22523 will be explained with reference to FIG. 2. In FIG. 2, a color comparison environment in which an observer 213 can observe a color matching area 209 in an achromatic color background 208 on the display screen of a CRT display 207 and a standard color chip 212 in an achromatic color object background 211 which is lighted by an illuminator 210 at the same time is provided. A light shielding board 214 is installed so as to prevent the CRT display 207 from irradiation of the illuminating light of the illuminator 210. Input signals into the CRT display 207 can be adjusted so that the color of the color matching area 209 matches the color of the standard color chip 212 in visual observation by the observer 213. In this color comparison environment, the mutual conversion method between the CIE tristimulus values of the standard color chip 212 which are known and the above input signals into the CRT display 207 is proposed by the chromaticity of luminescent material on the CRT display 207 and linear operation of the function expression of the gamma-th power characteristics. Furthermore, other inventions of the applicant which are related to the present invention are disclosed in Japanese Patent Application Laid-Open Nos. 5-69574 and 6-17998 (U.S. patent application Ser. No. 08/219,271, now U.S. Pat. No. 5,526,058).

For the art of color correction, design creation using a computer graphic apparatus is executed in various industrial fields such as cloth and accessory, apparel, automobile, domestic electric appliances, printing, and others. In these uses, not only rough color designing but also final designing or up to decision of design colors in a stage close to it are being increasingly often executed on a computer graphic apparatus.

Therefore, an art for eliminating a difference between a color on the color display screen of a computer graphic apparatus or on a printing paper of a color printer which is decided by visual evaluation of a designer and a color displayed on an actual trial product or on a product obtained by manufacture so as to produce the same color and for facilitating decision of a color by visual evaluation of a designer is necessary (when there is a difference between them such that they are not the same color, it is necessary to decide a color by visual evaluation in anticipation of the difference, so that the operation of visual evaluation will be much more complicated).

As one of the aforementioned arts, a system which can precisely control and define a color of a color display is disclosed in Japanese Patent Application Laid-Open No. 1-147989 (Japanese Patent Publication No. 4-44277) which corresponds to U.S. Pat. No. 4,843,573. This prior art will be explained hereunder with reference to FIG. 10. FIG. 10 is a block diagram showing the schematic constitution of a computer graphic apparatus. In the drawing, the computer graphic apparatus is constructed by connecting a color display 801 using a color CRT (cathode ray tube) 802 to a graphics workstation 805 including an input device 810 such as a keyboard, a programmable processor 808, and a memory 809 as shown in the drawing.

A user realizes and calculates a color space using the graphics workstation 805 and can designate the display color on the color CRT 802 by inputting color space coordinates from the input device 810. The color space used by this prior art is a uniform color space on the basis of the international standard system of the Commission Internationale de l'Eclairage (CIE) and indicates a perceptively uniform color change for a change in the color coordinates. When the display color to be displayed on the color CRT 802 is inputted from the input device 810, by predicting a color change (mismatch) between the displayed color on the color CRT 802 and the actual color which is calculated and realized by the graphics workstation 805 to a certain extent, the user can select the color efficiently on the input device 810.

In the aforementioned conventional example relating to a color reproduction system, although the color comparison environment is provided, a judgment of color matching is executed on the basis of visual comparison between colors. Therefore, there is a worry about variations in color matching accuracy between the light source color on the monitor display screen and the non-luminous object color due to the effect of the dependency of an observer for judgment of color matching. The dependency on the color comparison environment and imaging apparatus cannot be ignored and a problem of deterioration of color reproduction relating to color matching due to variations per hour of the imaging apparatus or variations in products arises. Particularly when transfer color data or retention color data is reproduced, there is a worry about remarkable reduction of the reliability of reproduced colors.

Color selection on the input device 810 according to the aforementioned prior art relating to a color correction system is based on the color coordinates or each primary color luminance data stored in the memory 809 and gradation correction, white balance adjustment, and variations in the luminescent material of the color CRT 802 are anticipated in the data. However, although the data may be calibrated periodically after it is set before the computer graphic apparatus is delivered from the factory, it is little compensated for the setting status of the color display 801 by the user and changes in the use environment.

Therefore, when a plurality of colors coexist as displayed colors like in a case wherein a natural picture is displayed on the color display 801, it is very difficult to reproduce each color faithfully. Furthermore, on the assumption that the reproduced color for the same color data is different between different kinds of imaging apparatuses which handle color images, it is necessary that a user makes a color design by keeping the corresponding color corresponding to the color data in mind.

SUMMARY OF THE INVENTION

To solve the above problems, an object of the present invention is to provide a system which can realize faithful color reproduction independently of an image apparatus and ensure the high reliability of color data among light source colors such as displayed colors and non-luminous object colors such as reflected colors and transmitted colors of the imaging apparatus.

Another object of the present invention is to provide an imaging apparatus having a means for compensating for a change which is caused in the reproduced color (displayed color) depending on a change in the setting status or use environment in an imaging apparatus such as a color display and for displaying the correct color and a means for realizing faithful reproduction of the same color for the same color data between a plurality of imaging apparatuses of different kinds and a color correction system including such imaging apparatuses.

To accomplish the above objects, the present invention is a color correction system for an imaging apparatus which has at least one of an imaging apparatus for detecting the color of at least one point of an object and an imaging apparatus for outputting image information, a conversion means for converting the color information of an input-output signal of the imaging apparatus on the basis of the color conversion characteristic of the imaging apparatus, a detection means for detecting at least one status value among the color information of an input-output signal of the imaging apparatus, at least one adjustment status set value of the imaging apparatus, and at least one status value indicating at least the variation per year of the color conversion characteristic and the use environment of the imaging apparatus, and a control means for controlling the color information of the input-output signal of the imaging apparatus by controlling the color conversion characteristic of the above conversion means on the basis of an output signal of the above detection means.

More concretely, the object for executing the above color reproduction faithfully is accomplished by connecting the output unit of a color data retention means having color data which is a reference value for the light source color and non-luminous object color to the control means via the conversion means in a color reproduction system for inputting or outputting an image signal handled by the imaging apparatus, connecting the detection means for detecting the image color inputted or outputted by the imaging apparatus to it, and connecting the output unit of the control means to the input unit of the conversion means. By doing this, the present invention performs the following characteristic operation.

Among these means, the conversion means converts different image signals before and after the conversion means so as to reproduce the image color handled by the imaging apparatus faithfully. The color data retention means retains color data which is a reference value for the light source color and non-luminous object color and supplies the color data to the control means whenever necessary. The control means compares the image color or image signal detected by the detection means with the color data and controls an output signal of the conversion means so as to make them equal to each other.

By installing these means, the image color handled by the imaging apparatus can be made equal to the color which is referred to on the basis of the color data. Therefore, the image color handled by the imaging apparatus can be reproduced faithfully.

To accomplish the above objects relating to a color correction system and others, in an imaging apparatus which includes image input and output devices such as a display device and print device, fetches a given image signal from an image signal processing means and outputs it to the image output device, and outputs an image signal fetched from the image input device to the image signal processing means, the present invention outputs the given image signal from the image signal processing means to the image output device via a converter (color converter) which can correct a color change which is caused by a change in the color display characteristic of the imaging apparatus or outputs the image signal fetched by the image input device to the image signal processing means via the converter. By doing this, the present invention performs the following characteristic operation.

In the imaging apparatus of the present invention, a user inputs or outputs an image signal in the format desired by him using the image input or output device. The converter installed in the imaging apparatus converts an inputted or outputted image signal using the conversion characteristic corresponding to a change in the setting status or use environment of the imaging apparatus so as to improve the faithful color reproduction of an image signal which is inputted or outputted by the input or output device. By improving the color reproduction of each imaging apparatus like this, a color correction system which can also realize faithful color reproduction

between a plurality of imaging apparatuses can be provided.

The foregoing and other objects, advantages, manner of operation and novel features of the present invention will be understood from the following detailed description when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the first embodiment of the high fidelity color reproduction system of the present invention.

FIG. 2 is a schematic view showing a conventional example.

FIG. 3 is a block diagram showing the second embodiment of the high fidelity color reproduction system of the present invention.

FIG. 4 is a block diagram showing the third embodiment of the high fidelity color reproduction system of the present invention.

FIG. 5 is a color space drawing showing an embodiment of color conversion of the high fidelity color reproduction system of the present invention.

FIG. 6 is a block diagram showing an embodiment of application of the present invention to a system of quick production to order.

FIGS. 7(a) and 7(b) are comparison drawings of flow before and after application of the present invention to a system of quick production to order.

FIG. 8 is a block diagram showing a color correction system as a basic embodiment of the present invention.

FIG. 9 is a circuit diagram showing a non-linear conversion circuit using an analog electronic circuit as an actual example of a converter.

FIG. 10 is a block diagram showing the schematic constitution of a conventional computer graphic apparatus.

FIG. 11 is a circuit diagram showing a linear conversion circuit as another actual example of a converter.

FIG. 12 is a circuit diagram showing a signal conversion circuit implemented by software as still another actual example of a converter.

FIG. 13 a block diagram showing a color correction system as another embodiment of the present invention.

FIG. 14 is a circuit diagram showing an actual example of the detector 7 shown in FIG. 13.

FIG. 15 is a block diagram showing the constitution of a detector for fetching setting control data as another actual example of the detector 7 shown in FIG. 13.

FIG. 16 is an illustration showing an example of an external light detector as an actual example of a detector for detecting a change in the use environment of an imaging apparatus.

FIG. 17 is an illustration showing an example of a cathode-ray tube beam current detector of a cathode-ray tube display as an actual example of a detector for detecting a change in the use environment of an imaging apparatus.

FIG. 18 is an illustration showing an example of a print color detector as an actual example of a detector for detecting a change in the use environment of an imaging apparatus.

FIG. 19 is an illustration showing an actual example of a detector for detecting the use time length of an imaging apparatus.

FIG. 20 is a schematic view of an imaging apparatus for explaining another embodiment of the present invention.

FIG. 21 is a schematic view of an imaging apparatus for explaining still another embodiment of the present invention.

FIG. 22 is a block diagram showing an embodiment wherein an image signal is shared as a standard signal between each signal processor and each imaging apparatus.

FIG. 23 is a block diagram showing an embodiment wherein image data can be passed between imaging apparatuses without passing through a signal processor.

FIG. 24 is a block diagram showing an embodiment wherein the present invention is applied to a computer system having various kinds of imaging apparatuses.

FIG. 25 is a block diagram showing the outline of a color matching system.

FIG. 26 is a block diagram showing an embodiment of the present invention which can ensure faithful color reproduction independently of an imaging apparatus in a color matching system.

FIG. 27 is a block diagram showing an embodiment in which an imaging apparatus 1 having a constitution which is the same as that shown in FIG. 13 can correct profile data for deciding the characteristic of a converter 3 which is provided in itself.

FIG. 28 is a block diagram showing still another embodiment of the present invention in a color matching system.

FIG. 29 is an illustration showing a displayed object image 80 and a background image 81 thereof of a display device 79 such as a high vision display.

FIG. 30 is an illustration showing a printed object image 83 printed on an output paper 82 of a print device such as a printer and a background image 84 thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be explained in detail hereunder using the embodiments. However, the present invention is not limited to the embodiments indicated below.

Embodiment 1

FIG. 1 is a block diagram showing the basic system of the present invention. In FIG. 1, a display signal inputted from a terminal 101 is converted by a converter 102 and then supplied to a display 103 so that faithful color reproduction is performed by the display 103. Needless to say, the terminal 101 is not limited to a single terminal as shown in the drawing and it may represent three input terminals for signals of three primary colors of red, blue, and green. The same may be said with the other terminals shown in FIG. 1. When faithful reproduction of displayed color is unimportant such as when the display 103 is used as a character monitor display, merely by supplying a display signal to the display 103 via the converter 102 as mentioned above, sufficient practical use can be obtained. However, when the display 103 is used for an order receiving system of various kinds of products as a graphic monitor display, an imaging apparatus and system which can faithfully transmit and reproduce the displayed color on the monitor display screen are necessary. However, as mentioned above, deterioration of color reproduction relating to color matching depending on product variations and variations per year between the imaging apparatuses is inevitable. Therefore, in FIG. 1, a controller 104 for controlling the conversion characteristic of the converter 102 is provided so as to compensate for the above deterioration of color reproduction. Namely, a sensor 106 for detecting the displayed color on the display 103 and a color data storage unit 105 for storing color data which is a reference value for the light source color and non-luminous object color are provided and the output terminals thereof are connected to the input terminals of the controller 104. The conversion characteristic of the converter 102 is corrected so as to make the output of the sensor 106 and the reference value output of the color data storage unit 105 equal to each other. In this case, the reference value output of the color data storage unit 105 may be corrected according to the system use status so as to obtain faithful color reproduction necessary for a user. By doing this, an imaging apparatus and system which can faithfully transmit and reproduce the displayed color on the monitor display screen by compensating for the deterioration of color reproduction relating to color matching depending on product variations and variations per year between the imaging apparatuses can be provided.

As color data stored in the color data storage unit 105, chromaticity such as Munsell or Ostwald color chips which are standards for the non-luminous object color can be considered. For example, it can be considered to digitize a parameter of XYZ tristimulus values in a CIE calorimetric system corresponding to each color chip number of the Munsell color chips. Therefore, existing parameters such as the above XYZ tristimulus values in the CIE colorimetric system, luminance (or a value converted from lightness), xy or uv chromaticity, and ab chromaticity can be used. Optional color parameters which are not standardized internationally also can be used. Since this digital data is a discrete value, when an intermediate value of data is inputted into the converter 102, it is converted by interpolation.

Embodiment 2

An operation example when the displayed color is faithfully reproduced will be explained using Embodiment 1. The present invention represents the color parameter of a Munsell color chip which is a standard of the non-luminous object color by digital data and fetches the digital data into the controller 104 using a CPU. The present invention inputs the display signal which is to be matched with the above Munsell color chip from the terminal 101 and reproduces it, for example, on the CRT of the display 103. The present invention detects the light source color reproduced on the CRT with the sensor 106 and then feeds it back to the controller 104 and compares it with the above digital data. The present invention checks whether a color which is the same as that indicated by the Munsell color chip is reproduced. When there is an e