JPS6017148B2 - Section diagram for chromaticity display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a section diagram and a modified Munsell symbol deterministic method for displaying chromaticity in a uniform display system converted from tristimulus values XYZ.

Subsequently, the color display system began with Munsell and was developed by the International Commission on Illumination (
CIE) developed into a chromaticity diagram.

Munsell uses symbols and numbers to display colors, but in principle it relies solely on visual perception, which has the drawback of making it difficult to ensure accuracy. The Cm chromaticity diagram is based on the stimulus values XYZ calculated from the values measured by a spectrophotometer, and provides highly accurate results. FIG. 1 is an explanatory diagram of a CIE chromaticity diagram. In reality, sections more subdivided than this explanatory diagram are used. In the positive region of the box axis, the curve with A and B as both ends is called spectrum locus 1, and the straight line at its base is called pure purple locus 2. All colors are inside this spectral locus and the pure violet locus. Chromaticity point P and achromatic chromaticity point W for plotting xy
The point P where the extension of the straight line 3 connecting the lines intersects with the spectrum locus 1
The wavelength indicated by ' is the dominant wavelength of the chromaticity point P. Therefore, a straight line originating from W and intersecting spectrum locus 1 represents a specific hue. The wavelength at one end A of the spectrum locus is 38 m, the wavelength at end B is 78 m, and P' on the diagram corresponds to 51 m. The axis passing through W and perpendicular to the xy coordinate plane indicates the brightness index Y. Therefore, a chromaticity diagram is created for each Y value. This CIE chromaticity diagram is the basis of current color display, but in recent years, color display alone is insufficient, and it has become increasingly necessary to accurately determine and display color shifts, that is, color differences. Looking at the Cita chromaticity diagram from this perspective, there is a drawback that color differences are not uniform over the entire color range. An improved version of this is U*V*W*, VxvYvz, Lab
, L*u*v*, L*a*b* color system, etc. Among these, the one most used in Japan is VxVY.
They are Vz series and Yamab series. The chromaticity diagrams of these improved color systems each exhibit isochronicity and represent color difference intervals that are proportional to the luminous differences over the entire color range. In Figure 2, the vertical axis of the orthogonal coordinates with the achromatic color chromaticity point as the origin is b and the horizontal axis is a, in the Kub color system, with red and yellow in the 10a and 10b areas, red and yellow in the 10a and 10b areas, It is a Hunter chromaticity diagram of the Lab color system in which purple is in the 1b region, green is in the 1a and 10b regions, and blue is in the 1a and 1b castles. Regarding a specific chromaticity point Q in this rectangular coordinate, the line segment OQ4 connecting it to the origin ○ represents saturation, and the angle 5 formed between OQ and a-koji represents hue (Dra of the International Commission on Illumination).
ftCIER Recommendation shipNovember, 19
(quoted from 75). Further, the axis passing through the origin 0 and perpendicular to the ab coordinate plane indicates the brightness index, and creating a chromaticity diagram corresponding to a specific brightness index is the same as the principle described in FIG. 1. By plotting Lab a and b obtained by measurement on a Hunter chromaticity diagram with this achromatic chromaticity point as the origin, △L, △ a,
By finding Δb from this figure, the color difference ΔE can be calculated using the following equation. △E (b) = [(△L) 20 (△a
)20(Δb)2]1/2 Also, as already mentioned, the scales determine the hue and saturation of the chromaticity point.

However, in the current state of using Hunter chromaticity diagrams or CIEI976 (L*u*v*) chromaticity diagrams, etc., which have been repeatedly improved as described above, it is difficult to specifically break down color differences and calculate hue shifts and saturation. It is not easy to determine the magnitude and direction of the deviation, and it is also not easy to convert the measurement results of the sample into a modified Munsell symbol.

The above-mentioned drawbacks are very important in the current state of industry, where accuracy and speed in color display and color difference measurement are urgently needed. The present invention eliminates the conventional drawbacks regarding color display and color difference measurement mentioned above, and achieves the objective quickly and accurately.

That is, this invention
Regarding the chromaticity points plotted on a chromaticity diagram in which the achromatic color chromaticity point is the origin of the orthogonal coordinates in a color system such as v*, for example, to explain the Buddha b system, the hue angle of chromaticity points a and b (
metric female (angle) is tan-1 (b/a
), and the saturation (memcchroma) is (a2
This invention relates to a section diagram for displaying chromaticity based on the principle of 1/2) and its application. This application consists of two inventions, and the first invention will be explained with reference to FIG. FIG. 3 corresponds to claim 1. Origin of Cartesian coordinates 6
10 and 0 yen are set at equal intervals with the center as equal saturation lines,
Further, 32 rays are provided so as to equally divide the angle 900 formed by the orthogonal circles 7 and 8 into nine equal hue lines. Furthermore, 0 circles are set up to equally divide each concentric circle, and 1 circle is set between each concentric circle.
Radiation is provided to divide the beats into equal parts. The subdivision of the same circle or ray is not limited to the above-mentioned equal divisions, but may be subdivided depending on the purpose. These subdivision lines are omitted in FIG. This section diagram can be used for reading the hue angle and saturation by plotting the chromaticity points on a paper printed with the orthogonal axis of the chromaticity diagram having Hunter chromaticity ab scale, or by printing it on a transparent plate. It can also be used as a scale. In addition to the Hunter chromaticity ab scale, a chromaticity diagram printed over the L*a*b*, L*u*v* color system can also be applied. A feature of this section diagram is that by plotting normal color representations such as a and b, the hue angle and saturation can be easily and accurately calculated using the same D circle as the radiation. This is because, based on the aforementioned principle, the angle that the line connecting the origin and the chromaticity point makes with the abscissa axis is the hue angle, and the length of the line connecting the origin and the chromaticity point represents the saturation. If you know the hue and saturation, the two colors are represented by brightness, hue, and saturation (L, HfC,) (LH x C2), so you can know the color difference △E by breaking it down into three components as follows. I can do it. Since the amount of color difference is expressed by length in three-dimensional coordinates, the three components of color difference, brightness difference, chroma difference, and hue difference, are also each expressed by length. However, the difference in hue angle between two colors expressed in terms of angle cannot be directly treated as one of the color difference components, so the hue difference is determined from the following relational expression. Color difference, △E=Zo△ze+△C210△day2 Hue difference △day=ノ△E21△ze−△〇Lightness difference △L=L1L2 Saturation difference △C=C,1C2 Like this If it can be separated into three components, it becomes clear which of the three components is most related even if the amount of color difference is the same, and this becomes very useful as a guideline when determining color matching or discoloration or fading.

FIG. 4 is an application example in which the color difference ΔB is decomposed into brightness difference, hue difference, and saturation difference, and the direction of each change is analyzed when determining discoloration or fading. 24 is a point plotted on the chromaticity display section diagram on the lightness plane of L from the results of La and Q measured by measuring the sample before the light resistance (weather) test,
25 is a point where the measured values L2a2b2 of the sample after the test are plotted on the chromaticity display section diagram on the lightness L plane.

It shows that the sample changed color and faded and moved from position 24 to position 25, and the magnitude of the color change and fading is 2, which represents the color difference △E.
It is expressed by the length of 8 line segments. As for the direction of color change and fading, the lightness difference is expressed by the length of 29 line segments, and according to FIG. 4, the lightness becomes brighter, and the hue difference is expressed by the length of 30 line segments. Indicates that the hue has changed from blue to green.
Further, the saturation difference is expressed by the length of 31 line segments, indicating that the saturation has decreased. A first embodiment of the above-mentioned first invention will be shown below.

In the above section diagram for displaying chromaticity, each ray represents a hue, and the radius of each circle represents saturation, so any chromaticity point, for example, b, can be placed on each hue line or saturation line. A chromaticity diagram is created by plotting a large number of points at appropriate intervals and pasting pieces of colored paper with hues and saturations corresponding to these points. In addition, multiple lightness axes L are shown in the peripheral margin of this section diagram, and pieces of colored paper with equal hue and saturation are pasted at appropriate intervals on each lightness axis to visually display the color (LHo C). The chromaticity diagram shown in The first embodiment falls under the scope of claim 2, and is shown in FIG. Similar to Buddha b, this kind of section diagram can be used in the L*a*b* color system, L*u*v* color system, etc. A transparent plate scale for reading hue angle and saturation as a second example of the first invention will be described next.

The section diagram for chromaticity display shown in FIG. 3 is printed on a transparent plate, and the hue angle number is marked at the same zero circle on the outermost periphery. Figure 6 (
(For convenience of drawing, the scale of this drawing is 1/2 that of Fig. 3.) In principle, the orthogonal coordinates of this section drawing are provided with a pivot axis 10 and a hole at one end of a rectangular transparent plate 11. It is possible to rotate freely while sliding on the section view transparent plate 9. On this rectangular transparent plate, as it rotates, a straight line 12 and its orthogonal line 13 are marked, which coincide with all the rays of the section diagram and their intersections with concentric circles. The space between these orthogonal lines 13 is further subdivided by marking one equal dividing line.
The transparent rectangular plate is provided with a slidingly movable argument tool (cursor) 14, and a straight line 15 perpendicular to the straight line 12 is marked on the cursor. To apply the transparent plate scale for hue angle and saturation reading described above to, for example, the L*a*b* color system, first, the orthogonal coordinates of the chromaticity diagram obtained by blotting the chromaticity point L*a*b* are Match the orthogonal coordinates of the scale above. Rotate the rectangular transparent plate and align the straight line 12 with the chromaticity point, and make the straight line 1
The angle between 2 and the abscissa axis, that is, the hue angle, is determined by the number marked on the outermost circle D. Next, the distance between the origin and the chromaticity point, that is, the saturation, is measured using the orthogonal line 13 of the straight line 12, that is, the scale. Note that the cursor straight line 15 is used to ensure accurate saturation reading. This is different from the one for reading the modified Munsell symbol in that only one transparent plate scale is required for reading the hue angle and saturation. Next, a modified transparent plate scale (chromaticity diagram) for reading Munsell symbols according to the second invention will be explained as a method of using the section diagram for displaying chromaticity according to the first invention.

First, nine transparent plates on which the chromaticity display section diagram shown in FIG. 3 is printed are prepared.

Modify each of the nine sheets to correspond to the Munsell lightness levels 1, 2, 3, ...9, and print out the hue lines and saturation lines corresponding to the lightness levels 1, 2, 3, ...9. , this is called a transparent plate scale. FIG. 7 is an explanatory diagram thereof, but the hue line and the saturation line are omitted and only a part of the chromaticity point with lightness of 5 is shown. Figure 8 shows the a*b* chromaticity diagram of the L*a*b* color system excluding the same D circle of the chromaticity display section diagram and radiation, and the correction of each hue and each depth corresponding to lightness 5. The a*b* chromaticity points of the Munsell symbol are plotted, and hue lines and saturation lines are drawn by connecting them. An example in which the present invention is applied to determining the modified Munsell symbol of arbitrary chromaticity points La and q plotted on the Hunter's chromaticity diagram shown in FIG. 2 or the chromaticity display section diagram shown in FIG. 3 will be explained. First, select a transparent plate scale corresponding to the modified Munsell brightness V, which corresponds to the brightness index LA (obtained from the conversion table), place it on the chromaticity diagram in which the a, b, and chromaticity points are plotted, and set the respective orthogonal coordinate axes. match. a, b,
The hue symbol marked on the hue line of the scale that matches the point.
Indicates the hue of b. Further, the saturation corresponding to the saturation line that matches the points a and b indicates the saturation of a and b. If a, b,
If it does not match the hue line or saturation line of the scale, the hue and saturation are determined by reading and interpolating the values corresponding to two adjacent hue lines or two saturation lines. In addition, regarding the modified Munsell symbol scale transparent plate scale (chromaticity diagram) of the second invention, the section diagram for displaying chromaticity is not printed on the transparent plate, and the modified Munsell brightness 1, 2, 3,... It is also possible to print only the corrected Munsell hue line and chroma line corresponding to each of the 9 lines and use this as a transparent plate scale, and the method of application thereof is the same as above. The above are application examples for Hunter's b system, but they include L*a*b* color system, L*u*v* color system, and U*V.
*W* Color system, Adams Nickerson VxVYVz
Color systems can also be applied in the same way.

That is, it is necessary to create a dedicated transparent plate scale for each color system. As already mentioned, various improved color systems have been devised and have been recommended by the International Commission on Illumination and are in widespread use, but there is a need to convert the color representation of these color systems into modified Munsell symbols. However, this work is tedious.

This invention enables rapid and accurate conversion. In carrying out the second invention, if the transparent plate scale for reading hue angle and saturation in the second embodiment of the first invention is used, reading the modified Munsell symbol becomes easier.

Set the chromaticity point of day 0, C obtained by measurement on the transparent plate scale for hue angle and chroma reading (with rectangular plate transparent scale) shown in Figure 4, and convert it to the modified Munsell symbol reading scale. The method of reading the modified Munsell symbol by superimposing it on the surface becomes more convenient, quick, and accurate by using a rectangular transparent plate at the kendori stage. The constituent functions of this invention have been described above.

Even though it is a uniform chromaticity diagram covering a three-dimensional area of colors in the improved color system, it is possible to only evaluate color differences, but it is possible to specifically break down color differences and calculate the size of shifts in hue and saturation. Determining the orientation is difficult and the modified Munsell symbol determination of the sample is cumbersome. However, with the method of this invention, such conventional cumbersome work can be done quickly and accurately.
Color management has become easier. The method of this invention can be applied to all color systems recommended by the International Commission on Illumination.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the CIE chromaticity diagram, Figure 2 is an explanatory diagram of the Hunter chromaticity diagram, Figure 3 is an explanatory diagram of a section diagram for displaying chromaticity,
Figure 4 is a color difference analysis diagram, Figure 5 is the first example of a section diagram for displaying chromaticity, Figure 6 is an explanatory diagram of a transparent plate scale for discussing hue angle and saturation, and Figure 7 is a modified Munsell symbol reading. Figure 8 is an explanatory diagram of the hue line and saturation line connecting the a*b* chromaticity points of the modified Munsell symbol. A, B...Spectrum locus end, 2...Pure purple locus, W...
...Achromatic color chromaticity point, P...Chromaticity point, P'.
...Spectrum locus intersection, 3...WPP' line, 0...Origin, Q...Chromaticity point, 4...OQ line,
5... QOA angle, 6... Section diagram orthogonal axes intersection, 7... Section diagram abscissa axis, 8...
...Section diagram ordinate axis, 9...Section diagram transparent plate, 10...Origin axis, 11...Rectangular transparent plate, 12...Line line of rectangular transparent plate , 13・
...Orthogonal line, 14...Cursor, 15...
...Cursor straight line, 16...50PB5/
8, 17, .・、、． 5 eaves 5/8, 1 8...
．． 5 to 5/8, 1 9...50Y5/8, 2
0. ．． ．． ...50YR5/8, 2 1. ．． ．． ．． ．． ．． 50R
5/8, 22….・．． 5 dishes P5/8, 23. ．． ．． 50P
5/8, 24... Plot point on brightness L surface, 2
5... Plot point on lightness L2 surface, 26... Lightness L, surface, 27... Lightness L2 surface, 28...
...Color difference △E line segment, 29...Brightness difference △L line segment,
30... Hue difference △H line segment, 31... Saturation difference △C line segment, 32... Colored paper piece, 33...
...Brightness axis, 34...Hue line, 35...Saturation line. Ice/Picture 2 Picture Outside 3 Picture Labor 4 Picture Saira Shibu 6 Picture Offshore 7 Picture Spear 8

Claims (1)

[Scope of Claims] 1. For a chromaticity diagram with an achromatic color chromaticity point as the origin of orthogonal coordinates, a number of circles of the same chroma display at equal intervals centered on the origin of orthogonal coordinates and orthogonal angles of the coordinate axes are used. FIG. 3 is a section diagram for displaying chromaticity formed by a ray of hue angle display divided into multiple equal parts. 2. In the section diagram for displaying chromaticity as set forth in claim 1, pieces of colored paper of the corresponding hue and saturation are pasted on each hue line and each saturation line at appropriate intervals, and what is the section diagram? The chromaticity display according to claim 1, characterized in that it is used as a chromaticity diagram formed by pasting pieces of colored paper of equal hue and equal saturation on a plurality of separately indicated lightness axes at appropriate intervals. section diagram. 3. A transparent plate marked with a section diagram for displaying chromaticity as set forth in claim 1, and the orthogonal coordinate origin of the transparent plate section diagram are used as a pivot point, and the transparent plate is slidable and rotatable; A rectangular transparent plate having a straight line passing through a pivot point marked so that it coincides with the intersection with the concentric circle of the entire radiation line and a pivot point that coincides with rotation, and a rectangular transparent plate fitted with a slidable reading device. The section diagram for displaying chromaticity according to claim 1, which is used as a transparent plate scale for reading hue angle and saturation. 4 Overlay the B chromaticity diagram or C chromaticity diagram marked on a transparent plate on the A section diagram or D, or combine the B chromaticity diagram or C chromaticity diagram with D to perform modified Munsell symbol reading. How to use the featured section diagram for displaying chromaticity. (a) A is a section diagram for displaying chromaticity formed by a large number of equally spaced concentric circles centered on the origin of orthogonal coordinates and rays for hue angle display dividing the orthogonal angles of the coordinate axes into many equal parts. (b) B is a chromaticity diagram in which the isochromatic lines and isochromatic lines of the modified Munsell chromaticity diagram are marked for different lightness levels, with the origin of the orthogonal coordinates being the grave color chromaticity point. (C) C is a chromaticity diagram in which isohue lines and isochromatic lines of a modified Munsell chromaticity diagram in which the origin of the A section diagram and the orthogonal coordinates are achromatic chromaticity are marked for different brightnesses. (d) D is connected to a transparent plate marked with the A section diagram, using the origin of the orthogonal coordinates as a pivot point, and is slidable and rotatable; A transparent plate scale for reading hue angle and saturation, comprising a rectangular transparent plate having a straight line passing through pivot points marked so as to coincide with each other, and a rectangular transparent plate having a perpendicular line thereto, and fitted with a slidable reading tool.