JPH0536328U - Color chart for color identification - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a color chart for color identification capable of reliably identifying various colors with a small number of charts. [Structure] A color solid 10 three-dimensionally represented by taking lightness on the vertical axis V, saturation on the horizontal axis H, and hue on the outer circumference P is based on preset gradations. And a first surface chart in which the color solid 10 is represented two-dimensionally when viewed from one direction (B direction) of the lightness axis V, and the color solid 10 from the opposite direction (C direction) of the lightness axis V. A color chart for color identification having three charts, that is, a second surface chart viewed two-dimensionally and a sectional chart in a state where the color solid 10 is cut at a central section (A section).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a color chart for identifying colors.

[0002]

[Prior Art]

 When performing plate-making printing, it is necessary to agree on the color between the manuscript creator and the printer. In addition, when an image is to be displayed on a monitor by computer graphics, it is necessary for the image creator and the computer operator to agree on color. Furthermore, if one wants to print an image imaged on a monitor by computer graphics on paper, there still must be a color agreement between the graphic designer and the printer. The color chart above is what is used to identify the colors in those cases.

Conventionally, as a color chart used for plate-making printing, there is one shown in Japanese Patent Publication No. 61-38465. Further, as a color chart suitable for image formation by computer graphics, there is one shown in JP-A-64-43732. Each of these color charts is created on the basis of a three-dimensional color solid in which the vertical axis represents lightness, the horizontal axis represents saturation, and the outer periphery represents hue.

[0004]

[Problems to be solved by the device]

 However, when various colors are identified using the conventional color charts described above, a large number of charts obtained by cutting a color solid with a large number of cross sections are required, and it is troublesome to prepare those charts. It was also troublesome to visually inspect a large number of these charts.

The present invention has been made in view of the above problems in the conventional color chart, and it is an object of the present invention to provide a color identification color chart capable of reliably identifying various colors with a small number of charts. To aim.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the color chart for color identification according to the present invention has a color solid represented three-dimensionally with brightness on the vertical axis, saturation on the horizontal axis, and hue on the outer circumference. A first surface chart in which each color element is divided into individual color elements based on a preset gradation, and the color solid is represented two-dimensionally when viewed from one direction of the lightness axis, and the color solid is the direction opposite to the lightness axis. It is composed of three charts, that is, a second surface chart which is two-dimensionally viewed from above, and a cross-sectional chart in a state in which the color solid is cut by an arbitrary cross section.

[0007]

[Action]

 The individual color elements on each of the above charts are expressed as color differences by the human eye due to the reflection of light, and at the same time, the three elements of colored light, namely red (R), green (G), and blue (B), are represented. It is individually expressed as a combination of gradations, or a combination of four gradations of printing color materials, that is, a combination of gradations of yellow (Y), magenta (M), cyan (C), and black (K). Therefore, by using these charts, the color of each element can be visually recognized, and at the same time, the gradation values of R, G, B or Y, M, C, and K that compose the color can be numerically confirmed. it can.

The color identification chart according to the present invention includes three charts, a first surface chart, a second surface chart, and a cross-section chart. By collecting two surface charts from the color solid, it is possible to obtain practically sufficient types of color elements without collecting many cross-section charts from the color solid. As a result, it becomes possible to perform quick and accurate color identification.

[0009]

【Example】

 Hereinafter, a color chart used for color identification when converting color data such as computer graphics represented by RGB data and color data such as printing represented by CMYK data is used as an example of the present invention. The color identification color chart will be described.

With the recent development of computer graphics (CG), image data produced by various related systems has been increasingly submitted to a printing company as a manuscript. In order to deal with such a case, a printing company has developed a conversion system for directly outputting CG data from a scanner to a plate-making film for printing.

However, image data used in CG usually has 256 gradations of 0 to 255 for R (red), G (green), and B (blue), respectively, while print data for printing is used. Is expressed in 100 gradations with a dot area ratio of 0 to 100% for each of C (cyan), M (magenta), Y (yellow), and K (black), and the color tones are considerably different. ing. Therefore, the current situation is that perfect conversion has not been made between them. Furthermore, due to variations in the monitors used during image production, there may be differences in the reproduction of color tones from those printed. Therefore, it has become necessary for the image creator and the person in charge of plate making / printing to have a common guideline for printing, that is, a guide.

The color chart for color identification, which will be described below as an example, serves as a common guide, that is, a guide for colors in both the image creator and the person in charge of plate making / printing in the above cases.

First, a method of creating a color chart for color identification will be described step by step. FIG. 1 shows a so-called color solid 10 in which the vertical axis V represents the lightness, the horizontal axis H represents the saturation, and the outer peripheral axis P represents the hue. The highest point P0 of the color solid 10 is an achromatic color having zero saturation and the highest lightness, that is, "white". On the other hand, the lowest point P1 of the color solid is an achromatic color having zero saturation and the lowest lightness, that is, "black".

The color solid 10 is three-dimensionally divided into 16 stages of 256 gradations from 0 to 255 of R (red), G (green), and B (blue) which are three primary colors of colored light. The color chart is divided, and the divided color solid is cut at the center of the lightness axis V to view the cross section in plan view, and a cross section chart 11 as shown in FIG. 2 is created. Further, when the color solid 10 is viewed from one direction of the lightness axis V, for example, the B direction, the upper outer peripheral surface of the color solid is viewed in plan, and the first surface chart 12 as shown in FIG. 3 is created. Further, when the color solid 10 is viewed from the direction opposite to the lightness axis V, that is, the direction C 2, the lower outer peripheral surface of the color solid is viewed in plan, and the second surface chart 13 as shown in FIG. 4 is created.

Each chart is represented by a regular hexagon having six points Y (yellow), G (green), C (cyan), B (blue), M (magenta), and R (red) as vertices. ing.

As described above, since the color solid 10 is divided into 256 gradations of RGB and 16 steps, each chart is also divided into 256 gradations of RGB and 16 steps. .. For example, looking at the first surface chart 12 of FIG. 3, this chart is divided into 33 columns from the leftmost end, the -17th column to the rightmost end, the 17th column, and the -17th column includes 17 color elements. The color elements increase by 1 as the number of columns increases to the right from that. Then, the maximum number of color elements is 33 in the first column in the center, and the number of color elements decreases by 1 each time there is an increase in the number of columns to the right from there, and there are 17 color elements in the first column.

Each color element has a rectangular shape, and has a color represented by a combination of different RGB gradation values. For example, looking at the 17th column, the color elements of the combinations shown in the RGB data sheet of Table 1 are arranged from the 1st address to the 17th address. The numerical values shown in this table are gradation values of R, G, and B colors. Address 1 is G (green) consisting of a combination of R (red): 0, G (green): 255, B (blue): 0, and address 17 is R: 0, G: 255, B: 255. C (cyan) which is a combination of Between address 1 to address 17, B (blue) changes in a state in which 256 gradations of 0 to 255 are divided into 16 levels. That is, the color elements that change color in 16 steps are arranged from G (green) to C (cyan).

For reference, the RG B data sheets for the 9th column, the 1st column, the 9th column, and the 17th column are shown in Tables 2, 3, 4, and 5, respectively. I will show you. Of course, RGB data sheets are individually created for each of the columns other than those. In addition, in FIG. 3, addresses 1, 9 and 17 in the -17th column, addresses 1, 9, 17, and 25 in the -9th column, 1, 9, 17, 25, 33 in the 1st column and 1 and 9 in the 9th column , 17 and 25, the RGB data of each color element at addresses 1, 9, and 17 in the 17th column are shown.

As described above, each of the first surface chart 12 when the color solid 10 (FIG. 1) is viewed from the B direction, the second surface chart 13 when viewed from the C direction, and the cross sectional chart 11 of the central A cross section An RGB data sheet for the chart has been obtained.

FIG. 5 shows an image production system including a keyboard 1, an image processing device (CPU) 2, and a CRT monitor 3. The RGB data obtained as described above is read into the image processing apparatus 2 via the keyboard 1 and stored in a predetermined address in the RAM, for example. After that, the stored RGB data is subjected to an image reproduction process and displayed as a color image on the monitor 3. That is, the regular hexagonal charts 11, 12, and 13 of FIGS. 2 to 4 are displayed on the monitor 3 individually or simultaneously on the screen in the form of a color image. Data may be input from a floppy disk drive or the like instead of the keyboard 1.

The computer graphics designer visually finds a desired color while looking at the image color chart displayed on the monitor 3 and confirms the column number and address of the color element, and RGB data sheet shown in FIG. 5 (of course, the RGB data sheet is not limited to Tables 1 to 5, but is prepared corresponding to the color elements of all columns and addresses of each chart of FIGS. 2 to 4). ), It is possible to know the RGB gradation value of the desired color.

In addition to the color image processing as described above, the RGB data is printed by a printing system configured by a keyboard 8, an RGB-CMYK conversion device 4, and a plate making / printing machine 5, as shown in FIG. Receive processing. The RGB-CMYK conversion device 4 has a storage device and a calculation device therein. The RGB data input via the keyboard 8 is stored in the storage device and further converted into CMYK halftone dot data values according to a conversion formula preset in the arithmetic unit. The CMYK halftone dot data values thus obtained are sent to the plate making / printing machine 5, and the plate making / printing machine 5 produces a color printed matter 6. Since three sets of RGB data are prepared corresponding to the three chart data of FIGS. 2 to 4, the color printed matter 6 to be produced is also included in the area chart 11 (FIG. 2) and the first surface chart 12 (FIG. 3). ), And three sets are produced corresponding to each of the second surface charts 13 (FIG. 3).

A person in charge of plate making / printing looks at the printed matter 6 produced, finds a desired color from the printed matter, and finds an RGB data sheet (for example, Tables 1 to 5) from the column numbers and addresses of the color elements. It can be used to know RGB data values. Further, by visually recognizing the color chart image displayed on the monitor 3, it is possible to visually compare the color on the printed matter 6 and the color on the monitor 3 corresponding to the same RGB data value.

In FIG. 5, the CMYK halftone dot data values obtained at the output terminals of the RGB-CMYK conversion device 4 are sent to the plate making / printing machine 5 and at the same time sent to the printer 7, where the data is printed by the printer 7. It is output in the form of a sheet. Tables 6 to 10 show a part of the CMYK halftone dot data sheet thus output. The 17th column, 9th column, 1st column of the first surface data chart 12 shown in FIG. The CMYK halftone dot data values corresponding to the color elements in the −9th column and the −17th column are shown.

As described above, the cross-sectional sheet 11 (FIG. 2) that is the central cross section of the color solid 10 (FIG. 1), the first surface chart 12 (FIG. 3) when the color solid is viewed from the B direction, and the color solid is the C direction. RGB data sheets (for example, Tables 1 to 5), CMYK data sheets (for example, Tables 6 to 10), color prints 6 and monitor colors corresponding to each chart of the second surface chart 13 (FIG. 4) viewed from Four points in the image are obtained. For the monitor color image, the image data for displaying it on the monitor is stored in a floppy disk or magnetic tape (MT) electrically and stored by a computer graphic designer or a platemaking / printing engineer. Get burned. One unit consisting of the above four elements is used as a guide for colors between the designer and the platemaking / printing technician, for example, as follows.

(1) Confirmation of a certain color on the color monitor and color reproduction when the color is printed. On the color monitor 3 of FIG. 5, a chart image corresponding to either the sectional chart 11, the first surface chart 12 or the second surface chart 13 is displayed, and the target color can be reproduced on the printed matter 6. Check.

(2) Know the RGB data of the color to be expressed on the color monitor or printed matter. A target color is selected from the color chart image formed on the monitor 3 or the printed matter 6, and the combination of RGB data constituting the color is read from the RGB data sheets exemplified in Tables 1 to 5.

(3) Know the CMYK data about the color that you want to express on a color monitor or printed matter. A target color is selected on the color chart image or the printed matter 6 formed on the monitor 3, and the combination of CMYK data constituting the color is read from the CMYK data sheets exemplified in Tables 6 to 10.

The values of the CMYK data illustrated in Tables 6 to 10 and the reproduced color of the printed matter 6 printed based on the values may change due to a change in the conversion formula in the RGB-CMYK converter. is there.

The cross-section chart 11, the first surface chart 12, and the second surface chart 13 shown in FIGS. 2 to 4 are in a state in which the color solid 10 is projected on a horizontal plane. With respect to G, C, M, Y, and color changes among the colors, a sufficient number of color elements are prepared for practical use. However, an achromatic color change, that is, a change from white to black is insufficient. Therefore, if accurate color recognition is required even for changes in achromatic colors, a color identification chart for achromatic colors may be prepared.

FIG. 6 shows an example of a color identification chart for such an achromatic color, a so-called gray chart. This achromatic color chart shows the color elements from RGB0 gradation to RGB255 gradation on the lightness axis V of the color solid 10 (FIG. 1) divided into 17 color elements. Also in this chart, as shown in the figure, 256 gradations of 0 to 255 are divided into 16 steps to divide each color element. As for the achromatic color chart, the RGB data sheet shown in FIG. 5 (refer to the RGB numerical data in FIG. 6) as in the cross-sectional chart 11, the first surface chart 12, and the second surface chart 13 in FIGS. ), A video screen on the monitor 3 (that is, video data recorded on a recording medium such as a floppy disk to create the video screen), created by the RGB-CMYK converter 4 based on the RGB data. The CMYK data sheet, and the four elements of the printed matter created by the RGB-CMYK conversion device 4 and the plate making / printing machine 5 are aligned. By using this achromatic color chart together, more accurate color identification of achromatic color and color tone adjustment of the monitor can be performed.

In addition to the stepwise achromatic chart including 17 color elements as shown in FIG. 6, the stepless achromatic chart as shown in FIG. It can also be used together with. In this stepless achromatic color chart, the brightness changes continuously from RGB0 gradation to RGB255 gradation.

The fact that the gradation in the color expression is 16 steps in the above embodiment means that when reproducing or expressing an image on a computer, most of the gradation is 256 gradations for each RGB. It is selected from a number that can be divided at equal intervals. Instead of the 16-step division, a finer 8-step division or a rougher 24-step division can be adopted.

However, with respect to the eight-step subdivision, most of the current color monitors cannot express the gradation, and the area per color on the monitor or the proof print is also small, so it is extremely discriminated. It may be difficult. Further, in the rough division of 24 steps, the number of colors of the expressed color elements becomes small, which may cause inconvenience in use. In consideration of the above points, it is preferable to divide the image into 16 stages as in the above embodiment, in consideration of the gradation expression capability and the ease of use. In this embodiment, the RGB data value or CMYK halftone dot data value of each chart displayed on the monitor 3 is output to the data sheet. However, the desired color of the chart can be specified on the monitor 3. It is also possible to display corresponding RGB data values or CMYK halftone dot data values on the monitor 3.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

[Table 5]

[0040]

[Table 6]

[0041]

[Table 7]

[0042]

[Table 8]

[0043]

[Table 9]

[0044]

[Table 10]

[0045]

[Effect of the device]

 According to the present invention, each color element is represented by only two surface charts and one cross-section chart, instead of collecting many cross-sections of a color solid to create a color chart, which is rare. The chart allows each color element to be displayed in a sufficient number for practical use, and facilitates visual color search.

[Brief description of drawings]

FIG. 1 is a perspective view showing a color solid.

FIG. 2 is a diagram showing a sectional color chart according to arrow A in FIG.

3 is a diagram showing a first surface color chart according to arrow B in FIG. 1. FIG.

FIG. 4 is a diagram showing a second surface color chart according to arrow C in FIG.

FIG. 5 is a schematic diagram showing an example of an electrical processing system for using the above charts.

FIG. 6 is a diagram showing an example of an achromatic color chart.

FIG. 7 is a diagram showing another example of an achromatic color chart.

[Explanation of symbols]

 10 color solid 11 cross section chart 12 first surface chart 13 second surface chart V brightness axis H saturation axis P hue axis

Claims (5)

[Scope of utility model registration request] 1. A color solid represented three-dimensionally with brightness on the vertical axis, saturation on the horizontal axis, and hue on the outer periphery, is divided into individual color elements based on preset gradations. Then, a first surface chart in which the color solid is represented two-dimensionally when viewed from one direction of the lightness axis, and a second surface chart in which the color solid is two-dimensionally viewed from the direction opposite to the lightness axis. A color chart for color identification, which is composed of three charts including a sectional chart in a state in which the color solid is cut in an arbitrary section. 2. A first surface chart, a second surface chart,
The color chart for color identification according to claim 1, wherein the sectional chart has a hexagonal overall shape. 3. The color elements of the color solid are red (R) and green (G) divided into 256 gradations from 0 to 255, respectively.
The color chart for color identification according to claim 1, wherein the color chart is represented by a combination of each color of blue and blue (B). 4. An achromatic color chart in which color elements on the lightness axis of a color solid are arranged is also provided.
Color chart for color identification described. 5. Each color element of the color solid is represented by a combination of each color of yellow (Y), magenta (M), cyan (C), and black (K) divided into gradations of 0 to 100. The color chart for color identification according to claim 1, wherein: