JPS60142206A - Net point area rate determining device - Google Patents

Abstract

PURPOSE:To determine a net point area rate with high accuracy by providing a means in which a color information - net point area rate converting table, and a means for storing color information derived by a color measuring means. CONSTITUTION:A color information selecting means 40 compares color information of a color information - net point area rate converting table stored in the first storage means 10, and color information of an object to be measured, stored in the second storage means 30. That which is the most similar to the color information of the object to be measured is selected from the color information of the color information - net point area rate converting table. A combination of the net point area rate corresponding to the color information selected from in the area rate converting table is outputted by a net point area rate output means 50. On the other hand, a combination of the net point area rate corresponding to the color information selected by the color information selecting means 40 is displayed by a corresponding color by a color display means 60. In this way, a net point area rate to be printed and overlapped can be determined easily, and whether the determined color can reproduce satisfactorily a color of the object to be measured or not can also be checked easily.

Description

DETAILED DESCRIPTION OF THE INVENTION Conventionally, in order to create printed matter, there is a C (for capturing color information from a color original and printing based on the image information).
cyan), M (magenta), Y (yellow), Bk (
Black) Divide the halftone dot area ratio of each plate and output each Iida net original plate film, or engrave each Iida printing plate by mechanical engraving method, laser engraving method, etc. 1 to gravure printing plate Is there a device known to create it?

In such a device, image information is stored in a flat storage device, and images can be freely set in the arrangement of the images, and even l
lI! There are products on the market that allow you to modify or change the color of a part or specific part of the iron, or to arrange specified colors in specified parts in a specified manner.

A typical device is what is commonly called a layout scanner. Devices such as such layout scanners are used to reproduce colors of image information.

The color or color to be set may be specified. In such a case, if the color is specified by the dot area ratio, it is sufficient to key in the value and there will be no problem. However, a problem arises when the color specification is done using a color sample.

When a color is specified using the R color sample, the following method can be considered as a method for inputting the information of that color in the form of a halftone dot area ratio to a device such as a layout scanner.

For example, assume that a printing layout sheet has a large number of color samples attached to it for specifying colors. For example, when it is desired to uniformly fill a background with a certain color, suppose that a small piece of paper having the color of the background is attached as a color sample (=1).

If you want to print the specified part with the same color as this color sample C
, M, Y, and Bk, to determine what dot area ratio to print, use this color sample and a color chart that prints with the dot area ratio changed at approximately 10% intervals. Visually compare the colors and select the most similar color, and use the fact that the percentage of the dot area of each plate is listed in Color Chart 1. It is common to determine the value and input it to the device. However, this method has the disadvantage that it takes time to compare, and the colors selected from the color chart vary depending on the person, so the determined halftone dot area size tends to vary. Accurately specifying the dot area ratio requires an experienced veteran, but even then it is not perfect.

On the other hand, there is currently a reflectance filter on the market that allows the dot area ratio to be calculated by measuring the density of the object to be measured. In this densitometer, the measured value is processed by a microcomputer built in the variable needle to calculate the halftone dot area ratio. The Niel-Nielsen equation is usually used to calculate the dot area ratio from this density value. In order to use this Niel-Nielsen equation, first measure the reference density, set the halftone area ratio of that part to the reference value (100%), and then measure the actual halftone area. It is necessary to measure the object to be measured with a high concentration and use the relationship with the reference concentration.

Therefore, it is only applicable to colors that have a standard density, and passing is only used for monochromatic colors. Moreover, the Niel-Nielsen equation can be established by ideally reproducing halftone dots without any dot gain, and by appropriately setting the shift coefficient based on the screen frequency, density, and paper transparency. Therefore, in actual use, it is not possible to accurately obtain a wide range of dot area ratios from light areas to shadow areas even when using a single color. It is even more difficult to calculate the dot area ratio for secondary colors.

Therefore, such a densitometer cannot display a combination of dot area ratios for each of the Y, M, C, and Bk versions to express the colors of the color sample.

In addition, such a conventionally known densitometer has the following reason for changing the halftone area ratio of Y and M to express the color of the color sample.
, C, and Bk cannot be displayed in combination. In other words, Y, M, and C printing inks are not ideal; Y ink contains M and C components, M ink contains Y and C components,
In addition, (for example, ink contains M and Y components. Since the Y, M, and C printing inks actually used are not ideal, color samples, etc. Nielsen's density value obtained by measuring the color of the object to be measured through B (blue violet), G (green), and R (white) filters, which are complementary colors of Y, M, and C. Even if the halftone area ratio is calculated using a formula, the value is not required in reality.

The dot area ratio of each positive chip of C is not shown.

This will be more clearly understood by the following example.

For example, if we assume that an image with a halftone area ratio of 100% is printed using only ink from a certain ink manufacturer, 1'14
/, L easy. Each of these printed matter ■ (filter,
If the density is calculated through the G filter and the B filter, it becomes 153.0.52.0.17, respectively, but these values are calculated as the halftone dots of the C, M, and Y versions, which are complementary colors of R, G, and B, respectively. It is clear that it cannot be used to calculate the area ratio.

This situation becomes more complex when not only one color of ink but a plurality of color inks are to be overprinted. Therefore, such density word 1 cannot be used to determine the halftone area ratio of the printing plate of each color on which the color of the color sample is to be reproduced.

The present invention eliminates the above-mentioned various drawbacks, and any color can be converted into Y, M, C color ink or Y
, M, C, and Bk colors, it is our intention to provide an apparatus that can easily determine how to combine the dot area ratios of each color plate.

Furthermore, depending on the color sample, it may be necessary to submit a color that is close to pure color or a fluorescent color, and in such cases, it may be difficult to reproduce the color without using special ink. The present invention aims to provide an apparatus that allows each user to determine whether or not the color of such a color sample can be reproduced with standard ink.

That is, the invention of this application stores a color information-dot area ratio conversion table indicating a correspondence relationship between color information and a combination of dot area ratios corresponding to the color information of color separation plates of a plurality of colors. a color determining means for measuring the color of the object to be measured and storing color information; a second storing means for storing the color information determined by the color measuring means; The color information of the color information-halftone area ratio conversion table stored in the first storage means is compared with the color information of the object to be measured stored in the second storage means, and the color information-halftone A color information selection means for selecting color information closest to the color information of the object to be measured from among the color information in the area ratio conversion table; and a combination of halftone area ratios corresponding to the color information selected by the color information selection means. It is an object of the present invention to provide a halftone dot area ratio determination device characterized by having a color display means for displaying a color corresponding to the color.

Note that as the color information, color degree, chromaticity, etc. can be adopted as the standard. In the following, the case where color density is used will be mainly explained for simplicity, but the same process can be performed even when chromaticity or the like is used as color information.

That is, it is well known that color density and chromaticity are used as one of the methods of expressing a certain color, that is, one of the color representation methods.

R (red), G (green), and B (blue violet l-) color systems are well known as color systems for color density.

The color system for chromaticity is the XYZ color system (CIE (+931
)X Y Z color system) and 1. 〒1) *Color system (CIEl
976 (L1'21"l)1') -Color
5pace) Various types of tubes are known.

In the XYZ color system, the chromaticities x, y, z are
Z is expressed as a tristimulus value, and the degree of similarity between two colors is the chromaticity difference ΔE=((Yl−Y,)2+(x,
5-x2)2+(y,-y2)+(yl-y2)2]1
/2.

Also, in the IJ"f b* color system, the chromaticities J, Sa, and b are expressed as, and the closeness of the colors of two buildings is the chromaticity difference △E =
C(L+″-L2*) 2-1-(a, *-22*)
2+(b, "-Ill 2") 2]'t.

As mentioned above, chromaticity and chromaticity difference are used to express colors and the closeness of colors.

Although the aforementioned color density and color difference are also used as methods to express colors and the closeness of colors, it is more convenient to use chromaticity and chromaticity difference when treating colors numerically. Especially L*a
The "I)" system is excellent in quantitatively handling colors that are close to those perceived by humans.

The present invention provides an apparatus that can measure the chromaticity, color density, etc. of the object to be measured and easily determine the halftone dot area ratio of each color plate when expressing the color of the object in print. This is what I am trying to do.

Furthermore, it is an object of the present invention to provide an apparatus that can actually display the colors to check whether the determined combination of dot area ratios is suitable or not.

Next, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a conceptual diagram of the device of the M invention of this application.
The storage means (10) stores in advance a color information-dot area ratio conversion table showing a correspondence relationship between color information and a combination of dot area ratios corresponding to the color information of color separation plates of a plurality of colors. A color measurement means (2) that records color information data of the object to be measured
The color information data determined by υ) is stored in the second storage means (3
0) A set of combinations of the three types of color densities obtained through the VC filter, G filter, and 13 filters, and furthermore, in addition to the above filters, for example, an amber filter, etc. or N I) A set of combinations of four types of color densities in addition to the color densities obtained through the filter, or chromaticity, etc. Next, the color information selection means (40) selects the above-mentioned The first storage means (10) stores the color information of the Vr-stored color information-dot area ratio conversion table and the color/IH information of the object stored in the second storage means (60). By comparison, the one closest to the color information of the object to be measured is selected from among the color information in the color information-dot area ratio conversion table.

In this way, the combination of dot area ratios corresponding to the color information selected from the color information-dot area tree conversion table as the one closest to the color information of the object to be measured is determined by the dot area ratio 111 output means (5D). Output. On the other hand, color information selection means (4
0) [Therefore, the combination of dot area ratios corresponding to the selected color information is displayed in the color display means (60) [Therefore, the combination of dot area ratios corresponding to the selected color information is displayed in the corresponding color.

Color display means include CRT, plasma display, electrochromic display, liquid crystal display,
Furthermore, various color + display devices such as liquid crystal displays combined with color stripe filters and fluorescent display tubes can be used, but 01 (T color display devices are the best in terms of color reproducibility).

As described above, when expressing the color of an object to be measured (for example, a color sample) by printing with printing ink, it is possible to easily determine the halftone area ratio to be printed with each color of ink, and this determination can be made easily. It is also possible to easily check whether the color obtained can satisfactorily reproduce the color of the object to be measured.

Figures 2 (a) and (b) show an example of a color density-dot area ratio conversion table when color density is used as the color information. On the left side, the combinations of color densities obtained through each of the R filter, G filter, B filter, and amber filter are shown, and on the right side, the halftone dots corresponding to the combinations of color densities shown on the left side are shown. Combinations of area ratios are shown.

Such a color density-dot area ratio conversion table is created as follows. First, print Y and M on the printing paper.

Using each ink of C and Bk, the halftone area ratio is 0%~
The color chart is created by actually printing and changing the color chart at appropriate intervals up to 100%, for example, in the case of Figure 2 (10% interval. In other words, in the example of Figure 2, the color chart is created by changing numbers 1 to 100%. Up to number 11, the M, Y, and Bk versions have a dot area ratio of 0%, and only the C version has a 10% change between 0% and 100%, and up to numbers 12 and 22, the dot area ratio is 0%. The dot area ratio is 0%, and the dot area ratio of the M plate is 10%, and C
Only the printing plates were changed in 10% increments between 10% and 100%. Create a color chart based on the combinations of .These 5 combinations are Y.
, C, and 13k, the halftone area ratio is 10%.
When changing at intervals, 11'-=14641 combinations are generated.

Combinations of color densities obtained through the R filter, G filter, and I3 filter for the colors tl and tt of the color chart created as above; filter or N1
) Add the color density obtained through the filter to the combination. In this way, a color density-dot area ratio conversion table is created that shows the correspondence between color density combinations and corresponding combinations of halftone area ratios of plates of each color for various colors.

Note that the above R and G. 13. Although color density is generally measured using an amber or ND filter, an interference filter or the like having a peak in the absorption portion of the spectral reflection curve of printing ink may also be used. The same filter used when creating the color density-dot area ratio conversion table must be used when measuring the color density of the object to be measured.

Looking at the color density-dot area ratio conversion table obtained as above, for example, for numbers 1 to 11 in Fig. 2, the dot area ratio of each plate is 4°Y, and 13 is Although it remains unchanged at 0% and only the C version changes, it is a complementary color of C (not only the color density through the filter, but also
The color density through the other G, B, and amber filters also changes.

This is because the C ink contains not only the C component lf but also other color components.

This relationship holds true for other inks as well, and they contain other components. Therefore, when determining the main halftone dot area of an object to be measured, it is necessary to take into consideration not only the color density through one filter but also the color density through other filters. The data of the color density-dot area ratio conversion table is stored in the first storage means (10), and an appropriate storage means such as a magnetic disk, floppy disk, 110M, etc. may be used. .

As described above, the color information-dot area ratio conversion table is stored in advance in the first storage means (10).

Further, the color measuring means (20) measures the color of the object to be measured to obtain color information, and FIG. 3 is a block diagram showing one embodiment thereof. The example in FIG. 3 shows an example in which color density is used as color information, and an object to be measured (1) such as a color sample is illuminated by a light source (21).
The reflected light is input to the photoelectric conversion element t23+ via a filter (22), where it is converted into an electrical signal h-. The filter (22) is the same one used when creating the color density-dot area ratio conversion table, and is
) A 7f filter, a G filter, a 6f filter with a 13 filter, or four types of filters 5-, which include an amber filter or an ND filter, are installed in a convertible manner. In this case, the filter may be switched electrically or manually. In addition, in the example shown in Figure 3, the light from the light source is emitted from an angle of 45 degrees and is received at a 45-degree angle, but the light is emitted from directly above and received at a 45-degree angle.
The light may be received in a direction of 5°.

The electrical signal generated by the photoelectric conversion element (23) is sent to the amplifier (
A
/1) The converter (27) converts the analog signal into a tenotal signal, and inputs and stores the color density as color information in the second storage means (30). The value of the electrical signal that has been logarithmically converted by the logarithmic converter (26) can be checked on a display meter (28). The display meter (28) is the A/I) converter (2
It may be displayed digitally by placing it after 7).

As described above, the color information of the object to be measured is obtained by determining the object to be measured for each filter.
Store it in the storage means (3 days). As the second storage means (30), an appropriate one such as a RAM can be selected.

The color information selection means (40) selects the combination of the color information of the object to be measured stored in the second storage means (30) and the first storage means (
10) Compare the color information stored in the color information-dot area ratio conversion table with the color information in the color information-dot area ratio conversion table, and select the color information closest to the color information of the object to be measured from among the color information in the color information-dot area ratio conversion table. However, the selection should be made as follows.For example, if color density is used as the color information, select one of the objects to be measured (through each of the filter, G filter, T3 filter, and amber filter). The color density obtained by The color density through the R filter, G filter, B filter, and amber filter at the eye number is 1. 'R(
11), T o (n), 1. 'n (n),'r
Let it be A(n). Next, the combination of the chromaticity of the object to be measured (I)
R, D a, D B, D A To color s i - Boat 1 combination at the nth number of color density in the halftone area ratio conversion table 'J,' R(n), To('n) -TB
(n ), q,'' A(n) distance SA (n
) is the minimum combination of color densities TR(n), TG
(n), T B (n), and 'J''A(n).

Distance 5A(n) is C8A(n):) 2=[Tu(n)-DR]2+CT
o(n)-n)o ]2-l-[: T n(n)-D
It can be determined from the relational expression: s:l2±CTAtn)-DA:)2.

Distance 5A (The value of n that minimizes nl is [5A(n)]
' corresponds to the minimum value of n. Therefore, using the above relational expression, change the value of n sequentially from n21 to the end to find the combination of color densities in the color density-dot area ratio conversion table that minimizes [5A(n)]2. By performing a search, the value of n that minimizes 5A(n) can be found.

S A (determine the combination of color densities in the color density-dot area drive conversion table corresponding to n where nl is the minimum as the one closest to the combination of color densities of the object to be measured, and The combination of halftone area ratios of each plate is determined for the corresponding Y, M, C, and 13.

Even in this case, if [5A(nl:l) becomes zero during the search, that is, during the search, the combination of the color densities of the object to be measured and the color density in the color density-dot area ratio conversion table If a match is found, the combination of halftone area ratios corresponding to the combination of color densities at the value of n at that time is the matte data, so the subsequent search may be discontinued.

The color information is selected as described in (2) below, but the same method can be used even when π chromaticity or the like other than color density is employed as the color information.

The combination of dot area ratios for each of the Y, M, C, and Bk versions determined as described above is outputted by the dot area ratio output means (50). The dot area ratio output means is for outputting the determined dot area ratio, and may be a display, a printer, or the like.

More than! Combination h of halftone area ratios output by IO<
″==indicates each dot area ratio, and if you print using each color ink based on the combination of the halftone area ratios output in this way, you can usually obtain a print that is the same or similar to the color of the object to be measured. For example, if the 125th color density is selected as the closest color density to a single color combination obtained by measuring the object to be measured, then from the table in Figure 2, the 6th edition is 60%, and the M edition is 60%. 0%, 10% for the Y version, and 0% for the Bk version.Therefore, by printing with each color ink in the output combination, the color of the object to be measured can be determined. It is possible to obtain printed matter that is the same as or similar to that.

However, as described above (if the color sample is a special color), it may not be possible to satisfactorily reproduce the color of the color sample with the combination of halftone area ratios determined as described above.

For example, offset process ink has ink turbidity, and a color sample that is close to a pure color is difficult to reproduce due to the combination of the dot area ratio of the process ink. An experienced veteran can judge to some extent whether or not the image can be reproduced satisfactorily by looking at the numbers for the combination of halftone area ratios obtained above, but it still depends on the person.
Alternatively, the judgment may vary depending on the case, or even worse, it may not be possible for an inexperienced person to make a judgment.

Even in such a case, according to the present invention, this judgment can be easily made based on the color displayed on the color display means (60).

Color display means (6o) It1 Generates signals for each dose of C, M, Y, and 13k according to the dot area ratios based on the data indicating the combination of the dot area ratios determined as described above. Then, the signal is passed through the multi-IJ circuit to It, , G
, B. Then, the color of the determined combination of halftone area ratios is displayed on a color monitor.

By comparing the color thus displayed with the color sample, it can be easily determined whether the determined color is appropriate or not.

However, there are cases where the color chart paper used to create the data for the color information/dot area ratio conversion table is different from the type of paper used for actual printing. Or, if printing is performed at an 11ill factory, the standard used at the printing factory when creating data for the color information-dot area ratio conversion table is There may be cases where the solid density values are different. In such cases, the conditions when creating the color information - halftone area reduction table are different from the conditions when actually printing. ,
When comparing the color information in the color information-dot area ratio conversion table and the color information of the object to be measured, it is necessary to take into account the differences in the conditions mentioned above.

Below we explain how to take into account such differences in conditions, or as it would be very complicated to completely compensate for the differences in conditions, in the example below: This shows the approximate correction value.

Figure 4 is a graph for explaining the relationship between color information and halftone area system, and shows an example when color density is used as color information. Although the explanation will be given assuming that the difference is white rice, the correction can be made using the same concept.

In Figure 4, when creating the color density-dot area ratio conversion table, the portion where only the C plate is 10[]% and all other plates are 0% is obtained through the R filter, which is a complementary color of C. The solid color density is Xc, all plates are 0%, that is, no ink is applied to the color chart paper, and the color density obtained through the R finoshita of the T/good part is Nc. .

Further, on the paper to be actually printed (C), solid printing is performed in advance using a C plate at a standard solid density determined as a standard solid density at the printing factory, using a C plate with a dot area ratio of +00%. This is applied to the paper that is actually to be printed.
The solid density of the plate is adjusted to 1. The color density measured through the T filter is Xc', and the color density obtained by measuring the unprinted paper through the R filter using the apparatus of the present invention is Nc'. shall be. Fourth
Directly in the figure! ](a) and (1)) respectively show the relationship between color density and halftone dot area ratio when creating a color density to halftone dot area conversion table and when actually printing is to be performed. In this case, if the object to be measured, such as a color sample, is obtained using the apparatus of the present invention and the color density is 1 (not obtained through a filter), then the dot area ratio is The dot area ratio y can be obtained by
A value different from the actual dot area ratio P is obtained. Therefore, in order to correct the error in this case, the color density value of the object to be measured is corrected as follows. In other words, when the color density Dc' obtained by measuring the object through the R filter is the corrected color density c, then XC-NC 1) c =: (Dc'-N c) X −+N c
According to the relational expression of Xc'-Nc',
, for those printed at 100% for only the Y version and 100% for only the Bk version, the G filter 5. Adjust the color density through B filter and Ampal filter,
Once you have recorded the colors that have passed through the G filter, B filter, and amber filter of the paper itself, use these color density data to filter the object to be measured through the G filter, B filter, and amber filter (or ND filter). The color densities obtained by
Use Bx for comparison with color density combinations in the color density to dot area flux conversion table. That is, when performing correction in this example, first, the color of the paper for actual printing is changed to R, G, R, G, etc. using the device of the present invention.
■The standard solid printing area of each color ink is set through the filters in step 3, and then at the printing factory, the reference solid printing area of each color ink is processed using the device of the present invention, with R filter for C ink, G filter for M ink, and B filter for Y ink. , Bk ink has a chromatic a degree measured through an amber filter. These data are stored in the device of the present invention (.Next, the color density of the object to be measured is measured using the device of the present invention through each filter of Tt, G, B, and amber. Correction is performed using the determined color density of the paper and the color density value of the reference solid print area.

In the correction example described above, the color density of the filter paper used for actual printing and the color density of the solid printed area of each color ink were actually measured using the apparatus of the present invention to obtain correction data. If the data is stored in advance, the data may be entered manually using a numeric keypad or the like.

Furthermore, another method of correction is to use a densitometer as a color density measurement means, in which the light and shadow areas can be adjusted independently for each of the R, G, B, and amber filters. It may be done as follows.

In other words, the light section measures the unprinted portion of the paper to be printed, and converts it to C1 of the color density halftone area ratio conversion table. 11. so that the color density is as shown in the case of number 1 in Figure 2). , G, 13, and Amber filters were adjusted, and the shadow areas were printed at a standard solid density for each color of paper C, M, Y, and ■31 (before printing). The solid density part of C ink is measured through an IT filter, and the color density of the dark part at this time is calculated when C in the color density - halftone area ratio conversion table is 100%. (In the case of number 11 in Figure 2) Adjust the R filter so that the color density is as follows.
-1 for M ink, Y ink and Bk ink for In
1 is also measured through the G filter, B filter, and amber filter, and the color density - halftone area ratio conversion table Y
The color densities of the G filter, B filter, and amber filter are adjusted so that each of , M, and Bk is 100%.

After making these adjustments, the actual object to be measured is measured to determine the combination of dot area ratios.

Various correction methods have been explained above, but all of them are 10
It is not something that can be corrected by 0%.

By the way, the accuracy of the halftone dot area ratio determined as described above depends on whether the halftone dot area ratio is created with an accuracy of 5 tx in the color information-halftone dot area ratio conversion table.

In the example shown in FIG. 2, the dot area ratio is changed at 10% intervals, so the accuracy is up to 10%.

Therefore, if you need a more accurate halftone area ratio, you can create a color information to halftone area ratio conversion table with the required accuracy, but if you do this, the color information - The amount of data in the dot area ratio intermeal table becomes extremely large, and creating such data is very time-consuming and requires a storage device with a large storage capacity. The disadvantage is that it takes a long time to perform the comparison operation.

In the following, an explanation will be given of interpolation that eliminates such drawbacks and determines the dot area ratio at intervals finer than the data interval of the dot area ratio in the color information-dot area ratio conversion table.

First, as described above, the color information is selected by the color information selection means (40),
If the color information obtained at the distance SA, = 00, that is, if it is selected as a result of completely matching the color information of the object to be measured, then the combination of dot area ratios corresponding to f is used as is. It may be outputted by the point area ratio output means (50). However, if the selected color information is
A. If selected in a case other than = 0, it is possible to interpolate the halftone area ratio corresponding to this selected color information and print a color that is even closer to the color of the object to be measured. A halftone dot area/halftone dot area ratio interpolation means can be provided as desired.

How to interpolate the dot area ratio will be described below based on its implementation.

First, from the color density-dot area ratio conversion table at 10% intervals as shown in Figure 2, the dot area ratio is closest to the color density combination cl (DR, DQ, DIl, DA) of the object to be measured. is selected, and its color density combination is t (TR.

′I゛0,′1゛B,′l”A) and it(/C)
). In this case, for example, it is assumed that the dot area ratio is on the order of 1%. In this case, the halftone dot area ratio to be determined must exist within the halftone dot area ratio shifted by half of 10%, that is, 5%, in the direction of magnitude with P as the center. In the following explanation, to simplify the explanation, C, M, Y, excluding Bk, are used as combinations of dot area ratios.
Although the explanation will be limited to the three colors, interpolation processing can be performed in exactly the same way even when Bk is not excluded.

Figure 5 shows points C and M that do not represent the dot area ratio, with the dot area ratio shifted by 5% in the direction of size with J) as the center.
, A (C+5, nl-5,
y+5), B (C-1-5, nl+5, y+5
), C(c-1-5, In + 5, y-5)
, D (C+5, m-5, y-5), E (c -5, f
1]-5, y+5), F (c-5, m +5, y+5
)*G(c-5,1η+5,y-5),H(c-5,1
11-5, y-5), and there is a halftone area ratio that fits into a solid having these points as vertices.

Therefore, divide this solid into parts with the required precision as shown in Figure 5, and calculate the color density combinations for each combination of halftone area ratios indicated by each grid point using the above formula to calculate the color density distance. It is preferable to select the point where the distance is the minimum and determine the combination of dot area ratios at that point as a combination of dot area ratios with increased accuracy.

However, the dot area ratios of the points A, B, C, D, E, F, G, and H are as described above (Fig. 1), but the color density corresponding to t''L is unknown. .

Therefore, A'(c + 1o, m
-10,y+10),B'(c+10,m-j
−I Q, y+1o), CCc+1o, fη]-10,
y-io), Jj (c +10, In -10, y-
10), g(c-10, m-10, y+io),
F'(c-10, m'-10, y+10), G'(c-
10,m+10゜y-1o), Il,'(C-10,m
-10, y-10) and their respective midpoints 1 (c, m
-1o, y-l-10), J (c, m+10, y+1
0), 1g (C1m +10, y+10), l, (c
, m -10,y -10), M(c -1-'I
O1+11.3++10), N(c+I 01jll-
1-1,0, y), O(C+10.11], y-10)
, Q(C+10, m-IO,y) R, (c, m
, y+10), S (c, m+10%y), T(c
, m, y -10), IJ (c, tn -10, y
), V(c-1υ, m, y+10), W(c-1
0, m→-10, y), X(c-1o, m, y-10
), Y (c=1o.

nl 10. Y), Z(c1i D, m, y),
Since the combination of color densities of ZZ (c -10, m, y) can be known from the color density-dot surface N ratio conversion table, first calculate the values of each density of each of these points and the color density of point P. The color density combinations of the points A, B, C, D, E, FSG, and J-1 are calculated by interpolation.

FIG. 6 shows the position of each point 10% away from point J on a c, M, y coordinate system representing the halftone dot area ratio.

First, a method of determining the combination of color densities at point A (c-1-5, τη-5, y+5) using an interpolation method will be described.

Point A is the point A'(c+1o, 1]1-10 in Figure 6.
, y+10 ), M (c −1-10, (η, y+1
0), Z (c +10, m, y), Q (c +10
, m-1o, y), I(c, m-10, y+10),
It (c.

nl, y+10), P(c, m, y), U(c, □=1
0, y) is located at the center of the cube. Therefore, calculate the average of each color density component of points A', M, Z, Q, I, R, P, and U, and use that value as the color density component of point A, that is, the combination of color density to point.

Note that the color density-dot area ratio conversion table shows equally spaced dots r.
If not created by M + product moment, point A', M
, Z, Q, [, R, P, U may be a rectangular parallelepiped rather than a cube. In that case, the distance from each vertex of the rectangular parallelepiped to a point will be different, so each It may be determined by using a proportional formula or an appropriate function depending on the distance between the vertices.

Similarly, for other points 13, C, D, E, F, G, and 11, the combinations of color densities are evaluated.

As above, points A, , B, C11), E, F, GII
Now that we have determined the combination of color densities for all of these points, we can use the color densities of these points to calculate the color densities of each grid point that divides the cube at required intervals as shown in Figure 5. The combinations are determined by an appropriate method such as proportional allocation in the same manner as described above. Next, it was determined like this f″12 The combination of the colors of the grid points and the color density of the object to be measured d O) R,
1,) G, I) u) Select the grid point that minimizes the distance SA between them. Since the combination of dot area ratios at the grid points selected in this way is already known, the combination of dot area ratios corresponds to the combination of dot area ratios P(c, m, y) of the object to be measured. The dot area ratio output means (50) outputs the interpolated data.

By the way, points A, B, and C as shown in FIG.

1], E, F, G, H, to determine the combination of color densities at all grid points with the required precision,
The number of grid points increases, making processing difficult. Therefore, consider eight small solid bodies whose diagonal lines are the lines connecting point P and each vertex in Figure 5. In this way, the color combination you are trying to determine will be included in one of these small solids. Where it is included is the combination d(])rt of the color of the object to be measured.
T) G, , DB) is determined based on which point of the color combinations of vertices A, -1-1 is closest to the combination.

If the small solid is not determined in this way, you can interpolate the combination of color densities of each grid point separated by the required accuracy only for this small solid, and then select this unwritten grid point. . In this way, the calculation time can be reduced to about one-eighth.

When the color information in the lust-dot area ratio conversion table and the color information of the object to be measured completely match, the halftone area ratio output means (50) corresponds to the matching color information. (ii) A combination of halftone dot area ratios is output, and if they do not match completely, a combination of halftone dot area ratios interpolated as described above is output.

Note that it is preferable to enter the required halftone area ratio using a numeric keypad or the like.

Figure 7 shows the device 6 in the invention of this application described above)
11 is a flowchart showing an example of how a combination of halftone area ratios is determined using color density as color information.

Figure 8 is an explanatory diagram of another interpolation method.
The axes represent the color densities obtained through hR, G, and B filters, respectively.
”B) is expressed as the origin.

Here, if we set the vector t d (B R113G, 13B), BR=1)11-'l"p+, B G=DG
=T O, B B = D B-T II tr, Hro.

Also, for the combination P (c, m, y) of the dot area ratio corresponding to the combination t of color densities, the halftone dots are shifted by one unit (that is, 10% in the case of FIG. 2). Set the area ratio combination P, (c±10.11]±10, y±10), and set the corresponding color density combination t3 (TR5,
TG5, TR5) can be known from the color density-dot area ratio conversion table.

The dot area ratio P3 (c±10, m±10, y±10)
Whether to take the positive or negative value is vector 13
It is determined depending on whether each component of td (BR, 13a, BB) is greater than or equal to zero or less than zero, and if it is greater than or equal to zero, it is taken as a plus, and if it is less than zero, it is taken as a minus. In this case, 13 R, B G, part 1 of 1311. Depending on its activation, each of C±10, m+10, and y±10 is V? The attachment to be adopted for the pair is determined.

can be expressed as a composition of several vectors.

Here, for the sake of simplicity, the following description will be made assuming that the boiling component of the vector 131d is greater than zero, but the same process can be performed even in other cases.

When the C component is 10% larger than the combination P (c, m, y) of the Ail halftone dot area ratio, and when the C component and the m component are each 10% larger, the combination of the halftone dot area ratios are respectively p+(c+10, nl, y) and 1]2(c-
1-10, m+10, y).

The combinations of color densities corresponding to the combinations Pl and P2 of the dot area ratios are tl(TBl, 'Fo+, 71''B+) and l'2(, respectively) according to the color density-dot area ratio conversion table.
Tr+2, '1. G2, 'I'B2).

-Can be expressed as It5.

It can be expressed as

Here vector I3 t d (B RlBG, BB)
As mentioned above (each component is known, so the above relational expression,
Calculate α, β, and r.

Therefore, the combination of color densities of the object to be measured is d(])R1■)G.

1) The combination of dot area ratios P(c) corresponding to the combination of color densities v7ct selected as the closest to B).

A combination of dot area ratios P'(c',
Since the table in FIG. 2 has an interval of 1n%, C'2C0 α×10 m' = m0 β×10 y'=y10 γxi.

becomes.

As described above, the combination p'(c'
, m',,y') are determined.

Note that there are various methods of expressing vector ] 13' t t 5 as a composition of other vectors in addition to those described above, and any vector may be used.

However, in order to obtain a reasonable interpolated value, the vector obtained by connecting the color density combinations obtained from the color density-dot area ratio conversion table is the color density combination L5, as shown in Figure 8. It is preferable to select the vector to reach K5.

If the vector method is adopted in this way, the processing time required for interpolation to find the combination of highly accurate dot area ratios can be extremely shortened.

Furthermore, interpolation of dot area ratio can be performed in the same way for chromaticity as well as color density.

Since the present invention has the following configuration, it has the following effects.

First of all, according to the apparatus of the invention of this application, even if the color to be reproduced in printing, such as a color sample, is not specified as an actual color, it is possible for an experienced person (and extremely It is possible to easily and quickly determine the positive halftone dot area ratio of each color that should produce the designated color.

Next, according to the device of the invention of this application, the halftone dot area ratio of the halftone positive chip of each plate is always determined in a standardized form, unlike the conventional method in which humans judge it, so it is possible to control the quality of printed matter. Burying becomes easier.

According to the invention of this application, in addition to the above-mentioned effects, by further employing an interpolation means, it is possible to extremely easily determine the dot area ratio with the required accuracy.

Furthermore, according to the invention of this application, it is possible to easily judge whether or not the determined color is appropriate by comparing the color displayed by the color display means with a color sample.

[Brief explanation of the drawing]

Figure 1 is: Conceptual diagram of Hiroaki's device, Figure 2 (a
), (bl is an explanatory diagram of a color density-dot area ratio conversion table, FIG. 3 is a d1z gravity specific gravity of one embodiment of the color density measuring means, and FIG. 4 is an explanation of the relationship between color density and dot area ratio. Figures 5, 6, and 8 are diagrams for explaining the interpolation processing method for the halftone dot area ratio, and Figure 7 is a graph for explaining the method of interpolating the halftone dot area ratio using the apparatus of the present invention. A flowchart of an example of the determination is shown below: (1)...Object to be measured (10)...First storage means;
(20)...Color density measuring means (21)...Light source (
22)・Filter (2, off・-photoelectric conversion element (
2.1)・Amplifier (25)...+iti positive circuit (2
6) Logarithmic converter (27) A/D converter (28) Display meter (30) Second storage means (40) Color density selection means (Section) Halftone area ratio output Means (60) Color display means Patent applicant Kazuo Suzuki Representative of Toppan Printing Co., Ltd. Figure 1; Figure 3

Claims (1)

[Claims] +1. ] a first storage means storing a color information-dot area ratio conversion table indicating a correspondence relationship between color information and a combination of dot area ratios corresponding to the color information of color separations of a plurality of colors; A color measuring means for measuring the color of the object to be measured and color information stored in a second storage means for storing the color information determined by the color measuring means, and the first storage means. The color information of the halftone area ratio conversion table and the second
color information selection, which compares the color information of the object to be measured stored in the storage means and selects the one closest to the color information of the object from among the color information in the color information-dot area ratio conversion table; means, halftone dot area ratio output means for outputting a combination of halftone dot area ratios corresponding to the color information selected by the color information selection means, and halftone dots corresponding to the color information selected by the color information selection means. 1. A dot area ratio determination device comprising: color display means for displaying a combination of area ratios in a color corresponding to the combination. (2) The combination of dot area ratios corresponding to the color information selected by the color information selection means is interpolated by the interpolation means that performs interpolation processing based on the @color scheme information-dot area ratio conversion table. A dot area ratio determination device according to claim 1, characterized in that: