JPS6039503A - Net point area ratio determining device - Google Patents

Abstract

PURPOSE:To determine easily a net point area ratio in a short time by deriving color information by measuring a color of an object to be measured, comparing it with color information of a color information - net point area ratio converting table, selecting the nearest one, and outputting a combination of a corresponding net point area ratio. CONSTITUTION:A color information - net point area ratio converting table is stored in the first storage means 10. On the other hand, a color information data derived by a color measuring means 20 for deriving a color information data of an object to be measured is stored temporarily in the second storage means 30. Subsequently, a color information selecting means 40 compares the color information of the color information - net point area ratio converting table stored in the first storage means 10, with the color information of the object to be measured, stored in the second storage means 30, and selects the nearest one to the color information of the object to be measured, from in the color information of the color information - net point area ratio converting table. A combination of a net point area ratio corresponding to the selected color information is outputted by a net point area ratio output means 50.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for inputting the dot area ratio of the color into a device.

Conventionally, in order to create printed matter, image information is captured from a color original, and halftone dots are used for each of C (Nan), ~1 (Magenta), Y (Yellow), and Bk (Blasov) versions for printing based on the image information. There is a device that calculates the area ratio and outputs a screen printing plate for each medication, or that engraves the printing plate for each medication using a mechanical engraving method, laser engraving method, etc. to create a Teflavia printing plate. Are known,.

In such a device, image information is stored in a storage device, and the arrangement of the images can be freely set, the color of a part or a specific part of the image can be modified or changed, or the color of a specified part or part of the image can be modified or changed. There are products on the market that allow you to arrange specified colors on parts in a specified manner. A typical device is commonly called a layout scanner. Devices such as such layout scanners are used to reproduce colors of image information.

When changing the color of a certain part or setting a digit in a device such as the layout scanner, the changed color or the 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 colors are specified using color samples.

When a color is specified using a color sample in this way, the following method can be considered as a method for inputting the color information in the form of a halftone 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, if you want to uniformly fill a background with a certain color, a small piece of paper with that background color is attached as a color sample.

If you want to print the specified part with the same color as this color sample C
．． M. Y. To determine what halftone area ratio to print for each Bk plate, visually look at this color sample and a color chart printed with halftone area ratios varied at approximately 10% intervals. The most similar color is selected by comparison, and the selected color is determined by using the fact that the percentage of halftone dot area of each plate is written on the color chart, and inputted into the device. It is common to do so. but,
This method has the disadvantage that it takes time to make the comparison, and the colors selected from the color chart vary depending on the person, so the determined halftone area ratio tends to vary.

Accurately specifying the dot area ratio requires an experienced veteran, but even then it is not perfect.

On the other hand, reflection densitometers that can measure the density of an object to be measured and calculate the dot area ratio are currently on the market. In this densitometer, the measured density value is processed by a microcomputer built into the densitometer to calculate the dot area ratio.To calculate the dot area ratio from this density value, Usually, the Niel-Nielsen equation is used.In order to use the Niel-Nielsen equation, measure the reference density in advance and set the dot area ratio of that part to the reference value (100%).
, then it is necessary to actually measure the dot area ratio of the target object and use the relationship with the reference density.

Therefore, it is only applicable to colors with a standard density, and is usually only used for monochrome colors.Furthermore, the Niel-Nielsen equation described above is based on the idea that halftone dots are ideally reproduced without any gain, etc. This is achieved by appropriately setting coefficients that vary depending on the number of lines, density, and transparency of the paper, so in actual use, even if it is a single color, a wide range of halftone area ratios from light areas to shadow areas is required. It is impossible to accurately obtain the dot area ratio, and it is even more difficult to calculate the dot area ratio of secondary colors or higher.

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 color of the color sample.

In addition, such conventionally known densitometers have a dot area ratio of Y, ~
1. It is not possible to display the combination for each version of C and Bk. That is, printing ink Y, 4. C ink is not ideal; Y ink contains M and C components, M ink contains Y and C components, and C ink contains M and Y components. Contains ingredients. Y, M, which are actually used
Because the printing ink for C is not ideal, the colors of the object to be measured, such as color samples, are changed to B (blue violet), G (green), and R (red), which are complementary colors of Y, M, and C. Even if the dot area ratio is calculated using the Wonniel-Nielsen equation based on the density values obtained by measurement through each filter, the value will not be the same as the actually required Y, M.

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

This will be better understood tomorrow by the following example.

For example, it is easy to understand if we assume that an image with a dot area ratio of 100% is printed using only C ink from a certain ink manufacturer. This printed matter is applied to R filter, G filter, respectively.
If you measure the density through the B filter, they are 1 and 53, respectively.
0.52, O, 1, 7, but these values are R
It is clear that this method cannot be used to calculate the halftone area ratio of Q, M, and Y plates, which are complementary colors of , G, and B.

This situation becomes even more complicated when not only one color of ink but a plurality of color inks are to be overprinted. Therefore, such a densitometer cannot be used to determine the halftone area ratio of a printing plate for each color that should reproduce the color of the color sample.
0 By the way, most of the parts expressed by the colors of the color samples attached to the printing layout paper for color specification are plain parts such as backgrounds of people and color bands.

In such cases, in most cases, it is sufficient to use three or fewer of the four inks of Y, M, C, and Bk to express the color of the color sample for color specification. be.

Therefore, the present invention eliminates the various drawbacks as described above, and is capable of expressing a color specified in a color sample with three out of the four color inks of Y, M, C, and Bk or less. An object of the present invention is to provide a device that can easily input information on how to combine the dot area ratios of each color plate into a device that is to reproduce or display the color.

That is, the first invention of this application is color information and Y, M, C corresponding to the color information of a color separation plate of a plurality of colors.

A color information-dot area ratio conversion table indicating a correspondence relationship with a combination of dot area ratios in which at least one of the four colors of Bk includes a dot area ratio of 0% is stored. a first storage means, a color measurement means for measuring the color of the object to be measured and storing color information, a second storage means for storing the color information determined by the color measurement means, and a second storage means for storing the color information determined by the color measurement means; The color information of the color information-dot 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 to calculate the color information-dot area. a color information selection means for selecting the color information closest to the color information of the object to be measured from among the color information in the ratio conversion table; and outputting 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 determining device characterized by comprising a halftone dot area ratio output means.

Furthermore, a second invention of this application provides an apparatus capable of outputting a more detailed combination of halftone dot area ratios using a table similar to the color information to halftone dot area ratio conversion table used in the first invention. This is what we are trying to provide.

Note that as the color information, color density, chromaticity, etc. can be used as a reference. In the following, we will mainly explain the case where color density is used for simplicity, but the same method can be used even when chromaticity etc. are used as color information.In other words, the method of expressing a certain color is the color system. It is well known that color density and chromaticity are used as one of the methods.

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

The color system for chromaticity is the XYZ color system (CIE (1931
)xyz color system) or I,'a' 1 color system (CI E
1976 (L'abob') -Color
However, various things such as S p a c e ) are known,
)′, Z are expressed as tristimulus values, and the chromaticity difference ΔE=((Yl −Y2)
2+ (XI X2)2+ (yl "l'2)""
It is expressed as

Also, in the Lab color system, chromaticity, a, b are x, y,
z is the tristimulus value, X01YO1ZO is the tristimulus value of the illumination light source, and the closeness of two colors is expressed as the chromaticity difference △E −C(L
-L52+(a--a2")"+(b9bF')l'.

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

Although the aforementioned color density and color density 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 handling colors numerically. .Especially I,”
Using the a"b' system is excellent for quantitatively handling colors that are close to the colors that humans sense.

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.

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 first invention of this application,
The first storage means (lO) stores color information and Y, M corresponding to the color information of a plurality of color separations in advance.

At least one of the four colors C and Bk has a halftone dot area ratio of 0%.A color information-dot area ratio conversion table is stored that shows the correspondence relationship with a combination of halftone dot area ratios. ,
The color information data determined by the color measuring means (20) for storing color information data of the object to be measured is temporarily stored in the second storage means (30). The color information data stored in the second storage means (30) includes, for example, three types of color densities obtained through each of the R filter, G filter, and B filter, which are the color densities of the object to be measured. A set of combinations, chromaticity, etc. Next, the color information selection means (40) selects the color information of the color information-dot area ratio conversion table stored in the first storage means (10) and the color information stored in the second storage means (30). The color information of the object to be measured is compared with the color information of the object to be measured, and the color information closest to the chromatic color NK 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 ratio conversion table as the one closest to the color information of the object to be measured is determined by the dot area ratio output means (5).
0) is output. As described above, when expressing the color of an object to be measured (for example, a color sample) by printing with printing ink, the halftone area ratio at which each color of ink should be printed is easily determined.

Figure 2 (aJ, (b), and (C) shows an example of a color density-dot area ratio conversion table as a color information-dot area ratio conversion table when color density is adopted as color information. , and on the left are I (filter, G filter,
The combinations of color densities obtained through each of the B filters are shown, and the combinations of dot area ratios corresponding to the combinations of color densities shown on the left are shown on the right.

This combination of dot area ratios is the smallest of the four colors Y, M, C, and Bk (one color includes a dot area ratio of 0%, and the three colors Y, M, C, Y, 3 colors: M, Bk,
The combinations of the three colors YLC, Bk, and the three colors M, C, and Bk change to various values.

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

Using a combination of the above three types of inks of C and Bk, the dot area ratio is set at appropriate intervals from 0% to 100%, for example at 10% intervals as in the case of Fig. 2. , and then actually print to create a color chart. That is, in the example of FIG. 2, numbers 1 to 1331 are combinations of three types of ink, C, M, and Y, and among them, numbers 1 to 11 are combinations of I't=1. The Y version has a dot area ratio of 0%, and the 6th version only has a 10% range between 0% and 100%.
Numbers 12 to 22 are changed by Y.
The halftone area ratio of the plate is 0%, and the halftone area ratio of the M plate is 10%.
Only the 6th edition is changed in 10% increments between 10% and 100%, and below, the halftone area ratio of each edition of Y, M, and C is changed by 10%.
Vary in % intervals. Similarly, numbers 1332 to 254
'l is a combination of three types of ink, M, C, and Bk; numbers 2542 to 3641 are a combination of three types of ink, Y, C, and Bk; numbers 3642 to 4641 are a combination of Y, M, and Bk. The combinations of three types of ink were each varied at intervals of 10% from 0% to 100% in dot area ratio. In this way, color charts with various combinations are created. Such a combination is Y, M
, C, and Bk, if the dot area ratio is changed at 10% intervals, 11'=14641 combinations are generated, but as in the case of the present invention (Y, M).

In the case of 8 combinations of ink baits for 3 of the C and Bk inks, 4641 combinations are sufficient.

An R filter and a G filter are applied to each color of the color chart created as described above.

Calculate the combination of color densities obtained through each filter of the B filter. Note that Bk ink is in the visible range. A0
Since the reflectance is considered to be almost constant in the wavelength range of 0 to 70 Q ng, there is no need to prepare a special filter to capture changes in Bk ink (any filter among It, G, and B can detect changes in Bk ink). Therefore, in the case of a combination of Bk ink and other inks, for example, a combination of M, C, and Bk, it is considered that the change in density through the B filter indicates the change in Bk.

Similarly, Y, C, Bk, Y, ~1. In the case of a Bk combination, the density through the G filter and the R filter respectively indicates the change in Bk. As described above, the color density - which shows the correspondence relationship between the combination of color densities and the corresponding combination of halftone area ratios of plates of each color for various colors.
A dot area ratio conversion table is created.

Although it is common to measure color density using the above-mentioned filters I (. The same filter used to create 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, in numbers 1 to 11 in Figure 2, the dot area ratio of each version of M, Y, and Bk is 0%. Even though only the 6th edition changes without any change in color density, not only the color density changes through the R filter, which is the complementary color of C (but also the color density changes through the other G and B filters). are doing.

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

This relationship is the same for other inks as well.
Contains other ingredients. Therefore, when determining the dot area ratio 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 such a storage means may be a magnetic disk, a floppy disk, a ROM, or the like as appropriate.

As described above, color information -
A dot area ratio conversion table is stored.

In addition, the color measuring means (2) measures the color of the object to be measured to obtain color information, and FIG. 3 shows a block diagram showing one embodiment of the method. , shows an example in which color density is used as color information, in which an object to be measured (1) such as a color sample is irradiated by a light source (21), and the reflected light is transmitted to a photoelectric conversion element via a filter (22). (
23), where it is converted into an electrical signal. The filter (22) is the same as the one used when creating the color density-dot area ratio conversion table, and three types of filters, R filter, G filter, and B filter, are attached so that they can be converted. It is something. 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° and is received directly above, but it is also possible to emit light from directly above and receive the light from a 45° direction. It's okay. The electrical signal generated by the photoelectric conversion element (23) is amplified by an amplifier (24), subjected to necessary correction by a correction circuit (25), and subjected to logarithmic conversion processing by a logarithmic converter (26), and then sent to an A/D converter. The converter (27) converts the analog signal into a digital signal, and stores the color density as color information in the second storage means (
I) and stored. Note that 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 @3) may be placed after the A/D converter (Shu) to provide a digital display.

As described above, the object to be measured is measured for each filter to obtain color information of the object to be measured, and these are stored in the second storage means (30) as described above. 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 is made as follows. For example, when color density is used as color information, the color density obtained through the R filter, G filter, and B filter of the object to be measured is DR, DG, and D.
a, and the chromatic a degree through the R filter, G filter, and B filter at the nth number of the color information-dot area ratio conversion table of the color density-dot area ratio conversion table is 1, respectively.゛R(珘T c(n),
'l'n(n).Next, the combination DR, DG, DB of the color densities of the object to be measured and the combination T a of the nth number of color densities in the color density-dot area ratio conversion table. (n
The distance S A (n) between l, T c (n and TB (n))
The combination of color densities T R (nl, T
Find c(n) and T n(n).

Distance 5A(rJma(sA(n172= (rR(nhiDR) 2 + (
Tc(n) −DcJ 2+[r B(n)−D B)
It can be determined from the relational expression 2.

The value of n that minimizes the distance 5A(n) is C8A(n), l
2 corresponds to the minimum value of n. Therefore, using the above relational expression, select the combination of color densities in the color density-dot area ratio conversion table that minimizes [5A(n), 12] rl=
1! l. et al. The combination of color densities in the halftone area ratio conversion table is determined as the one closest to the combination of color densities of the object to be measured, and the halftone dot surfaces of the Y, M, C, and Bk versions corresponding to that combination of color densities are determined. A combination of 2i rates is determined.

Even in this case, if (SA(n))2 becomes zero during the search, in other words, during the search, the combination of color densities of the object to be measured and the color in the color density-dot area ratio conversion table are 'If a match in density is found, the data determines the combination of halftone area ratios corresponding to the combination of color densities at the current value of n, so you can abort further searches. .

Although the color information is selected as described above, the same process may be performed even if chromaticity or the like is used in addition to color density as the color information.

Y, I't, 1. determined as above. C,B
The combination of halftone dot area ratios of each version is determined by the halftone dot area ratio output means (5
0) is output. The dot area ratio output means is for inputting the determined dot area ratio to an external device such as a layout scanner, and once the dot area ratio is outputted to a data storage medium such as a fluoropy disk, magnetic tape, or paper tape. The point area ratio data may be stored and input into an external device, or may be directly input without being stored.

Alternatively, the dot area ratio output means may be a device for displaying the dot area ratio, such as a printer, a liquid crystal display device, a CR'l'' display device, or the like.

The combination of the halftone dot area ratios output as described above indicates the halftone dot area ratio of each plate, and if the combination of the halftone dot area ratios outputted in this way is used to print with each color ink, the object to be measured will be printed. It is possible to obtain printed matter with the same or similar color. For example, if the 1st and 25th color densities are selected as the closest color densities to the combination of color densities obtained by measuring the object to be measured, then from the table in Figure 2, the 6th edition is 30%, and the M edition is 0%. %, 10% for the 7th edition, and 0% for the Bk edition by the dot area ratio output means. Therefore, by printing using the ink of each color with the combination output here, the color of the object to be measured is the same as that of the object to be measured, or it is approximated to it. The type of paper used for the color chart may be different from the type of paper used for actual printing. This is the solid density value used as the standard when creating the data for the color information-dot area ratio conversion table, and the solid density value used as the standard at the printing factory when actually printing at that printing factory. may be different. In such a case, the conditions for creating the color information - halftone area ratio conversion table and the conditions for actual printing are different, so the color information in the color information - halftone area ratio conversion table is different. When comparing the information with the color information of the object to be measured, the difference in the conditions described above must be taken into consideration.

An example of how to take such a difference in conditions into account will be explained below, but since it would be extremely complicated to completely compensate for the difference in conditions, we will use the following method. In the example below, (* indicates the case of approximate correction.

Figure 4 is a graph for explaining the relationship between color information and halftone area ratio, and shows an example when color density is used as color information.For simplicity, it is assumed that these are in a linear relationship. As will be explained, correction can be applied to curves by applying the same concept.

In Figure 4, when creating the color density-dot area ratio conversion table, the portion where only the 6th edition is 100% and all other editions are 0% is converted through the R filter, which is the complementary color of C. Assume that the obtained color density is Xc, and that all the plates are 0%, that is, the color density obtained through the R filter in the part where no ink is applied to the color chart paper is Nc. On the actual paper to be printed, solid printing is performed in advance using a 6-plate with a density determined as the standard solid density at the printing factory and a plate with a halftone area ratio of 100%. The color density of the 6th plate printed on the paper to be printed is measured using the apparatus of the present invention through the R filter, and the color density is Xc. Assume that the color density obtained by measurement through the R filter is Nc.
In the figure, the straight line (a) and the straight line fbl are respectively color density -
It shows the relationship between color density and dot area ratio when creating a dot area ratio conversion table and when actually printing. In this case, the object to be measured, such as a color sample, can be measured using the device of the present invention.
・If the color density obtained through the R filter is Dc', then if you calculate the dot area ratio without making any corrections, you will get the dot area ratio P', but in reality, This results in a value different from the dot area ratio P that should be calculated. Therefore, in order to correct the error in this case, the color density value of the object to be measured is corrected as follows. That is, the color density D obtained by measuring the object to be measured through the R filter
JJ-', where the color density after correcting the value of c' is Dc;
In this case, the color density of the object to be measured obtained through the R filter is corrected according to the relational expression. Similarly, only the M version is 10
For those printed at 0% and only the Y version at 100%, the color density is determined through the G filter and B filter respectively, and for those printed only at the Bk version at 100%, R, G, The color density is set through one of the filters B, and then the G filter of the paper itself,
The color density through the fill letter is recorded, and these color density data are used to compare the measured object with the G filter and the B filter. That is, when performing correction in the case of 91, first, the color density of the paper to be actually printed is adjusted to 11.
The standard solid printing part of each color ink at the printing factory is installed in the apparatus of the present invention through G and B filters (C ink G and R filters, M ink G filter, Y ink Woma B filter , Bk ink is R,
, G, and B, record the color density measured through one of the filters. These data are stored in the device of the present invention. Next, the color density of the object to be measured is measured through R, G, and B filters using the apparatus of the present invention, and the color density of the paper and the color density value of the reference solid printed area are calculated. Use this to make corrections.

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

Furthermore, as another method of correction, if a densitometer is used as the color density measuring means, and the light part and shadow part can be adjusted independently for each of the R, G, and B filters, the following method may be used. good. In other words, the light section measures the unprinted part of the paper to be printed,
R, G, and B filters are used so that each of C, M, Y, and Bk in the color density-dot area ratio conversion table has a color density of 0% (in the case of number 1 in Figure 2). Adjust the density and move the shadow area to the paper C0 to be printed.
゜Prepare a print with a standard solid density for each color of Y and Bk, measure the solid density part of C and ink through an R filter, and measure the color density of the shadow part at this time. , C in the color density-dot area ratio conversion table is 1
00% (No. 11 in Figure 2), adjust the color density of the R filter, and similarly, adjust the color density of the G filter and B for M ink, Y ink, and Bk ink.
Y, N, l of the color density-dot area ratio conversion table measured through a filter. Adjustments are made so that the color density of the G filter and the B filter is the same as when each of 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's not something that can be corrected by 0% (・.

Figure 5 shows the results using the device of the present invention including such corrections.
This is a flowchart showing how the combination of halftone area ratios is determined using color density as the color information as an example.

In addition, in FIG. 5, the number of the color density-dot area ratio conversion table when the distance becomes the minimum value is memorized, and the dot area ratio is calculated from this number.
This is possible by determining in advance how many percent intervals the halftone area ratio of each plate is to be changed and in what order they are to be arranged. In this case, the first storage means does not have to store data on halftone area ratios, but can store only data on color density combinations in a predetermined order. (It is convenient because it only takes a few minutes, so it is possible to use a storage means with a small storage capacity.

The accuracy of the halftone dot area ratio determined as described above depends on the accuracy with which the halftone dot area ratio in the color information-halftone dot area ratio conversion table is created. Second
In the example shown in the figure, the halftone dot area ratio is made by changing at 10% intervals, so the accuracy is up to 10%.

Therefore, if a more accurate halftone area ratio is required, it is sufficient to create a color information - halftone area ratio conversion table with the required precision. The amount of data in the area ratio conversion table is extremely large, and creating such data is extremely time-consuming and requires a storage device with a large storage capacity. The disadvantage is that the comparison operation takes a long time.

The second invention of this application eliminates such drawbacks and is capable of determining and outputting halftone area ratios at intervals finer than data intervals of halftone area ratios in a color information-halftone area ratio conversion table. The aim is to provide a device that can.

That is, the second invention of this application provides color information and four colors of Y, M, and C10k corresponding to the color information of a color separation plate of multiple colors.
a first storage means storing a color information-dot area ratio conversion table indicating a correspondence relationship with a combination of dot area ratios in which at least one of the colors includes a dot area ratio of 0%; , a color measuring means for measuring the color of the object to be measured and storing color information;
a second storage means for storing the color information determined by the color it'11 determination means; and color information of a color information-dot area ratio conversion table stored in the first storage means. Comparing the color information of the object to be measured stored in the second storage means, selecting the one closest to the color information of the object from among the color information in the color information-dot area ratio conversion table. a color information selection means; when the selected color information and the color information of the object to be measured do not match, the color information is determined after determining a combination of ink types to be interpolated based on the selected color information; - halftone area rate interpolation means for determining a combination of interpolated halftone area rates based on a halftone area rate conversion table; and a dot area ratio output means for outputting a combination of interpolated dot area ratios and, if they match, outputting a combination of dot area ratios corresponding to the selected color information.

FIG. 6 is a conceptual diagram of the device of the second invention of this application,
The first one stores the color information-dot area ratio conversion table.
The storage means (10), the color measurement means (20), the second storage means (30), and the color information selection means (40) are the same as those in the first invention, and the apparatus of the first invention Similarly, the color information closest to the color information of the object to be measured is selected from the color information-dot area ratio conversion table.

If the color information selected in this way is at the distance SA-〇, that is, if it is selected as a result of completely matching the color information of the object to be measured, the corresponding combination of halftone area ratios will be used as is. It may be outputted by the dot area ratio output means (70). However, if the selected color information is other than 5A=O, the halftone area rate interpolation means ( 60) to input a combination of halftone dot area ratios that can print a color that is even closer to the color of the object to be measured.The interpolation of the above halftone dot area ratios can be performed using an appropriate method. Bye.

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

First, the one closest to the color density combination d (DR, DC, DB) of the object to be measured is selected from the color dot area ratio conversion table with dot area ratios in 10% intervals as shown in Figure 2. , the combination of color densities is t(TR1TG, TB), and the corresponding combination of halftone area ratios is P(c, m,
y, bk). In this case, for example, it is assumed that the dot area ratio is on the order of 1%. In this case, the selected color density combination d (DR, Da,
DB) color information-dot area ratio conversion table number is 1
If the number is between 1331 and 1331, go to C6.1. Interpolate with the combination of Y, and if the following numbers are between 1332 and 2541, Bk
, If the combination of C, M is between numbers 2542-3641, then the combination of Bk, C, Y, numbers 3642-464
If it is between No. 1, interpolation may be performed using a combination of Bk, N1, and Y. Therefore, first, a combination of ink types to be interpolated is determined based on the selected combination of color densities. Next, the dot area ratio that should be found among the types of ink determined in this way exists within the range where the dot area ratio is shifted by half of 10%, that is, 5%, in the direction of magnitude with P as the center.

Note that the following can also be interpolated in exactly the same way.

Figure 7 shows the halftone dot area ratio with P as the center +5%, m
+5, y-5), D(c+5, m-5, y-5), E(
c-5, nl-5, y-1-5), F(c-5, m+5
, y+5), G(C-5, In+5, y-5), H(c
-5, m-5, y-5), and there is a dot area ratio that fits into a solid having these points as vertices.

Therefore, divide this solid into parts with the required accuracy as shown in Figure 7, and calculate the color density combinations for each combination of halftone area ratios shown by each grid point using the above formula to calculate the color density distance. The point at which the distance is the minimum may be selected, and the combination of dot area ratios at that point may be determined as a combination of dot area ratios with increased accuracy.

However, although the dot area ratios of the points A, B, C, D', E, F, G, and H are known as described above, the corresponding color densities are unknown.

So it was 10% further away from P” (C+I Q, m
-10, y+to), B'(c+10, m+10, y+
IO), C(c+ 10', m+ 10.3'-10
), d(c+30.m-10, y-1, E'(c-1
0, m-10, y-+-t O), F'(c-IQ, +
11+10, y+10), G'(c-10, m+10,
y-10, FI' (C-10, m-10, y-10) and their respective midpoints J (c, m-10, y + 10)
, J (c, m+1 0 , Y+10), K(c, m
-1-10, y-10), L(c, m-10, Y-10
), ~I(c+IQ, m1y-zQ), N(c+10'
-m+1 o, y ), 0 (c -4-10, m.

Y-10), Q(C+1 o, m-10, y), R(c
, m, y+to), S (c, m'+10, y),
'1' (C, m, y-10), U (c, m-10, y
), V(c-10, In, Y+1 0 LW(mu-
Since the combination of 1011n+101 color densities can be known from the color density-dot area ratio conversion table, first, using the color density values of each of these points and the color density value of point P,
, B, C, D, E, F, G, and H by interpolating the combination of color densities.

FIG. 8 shows the position of each point 10% away from point P in the C, M, Y coordinate system representing the halftone area ratio.

First, a method for determining the combination of color densities at point A (C+5, m-5, y+5) using an interpolation method will be described. Point A is A(c+10, m-10, Y+10), M in Figure 8.
(C+10, m, y+10), Z (C+10, m, y)
,Q(c+10,m-10,y),I(c,m-10,
y+10), R(c, mSy+10), P(c, m
, y), and U(c, m-10, y).

Therefore, the average of each color density component of points A', M, Z, Q, I, R, P, and IJ is calculated, and the value is taken as the color density component of point A, that is, the combination of the color density of point A.

Note that if the color density-dot area ratio conversion table is not created using equally spaced dot area ratios, points A', 81,
The solid composed of Z, Q, ISR, P, and U may be a rectangular parallelepiped instead of a cube, and in that case, the distance of point A from each vertex of the rectangular parallelepiped will be different, so from each vertex Use a proportional calculation formula or an appropriate function depending on the distance of °C.
All you have to do is make it easier.

Similarly, the combinations of color densities are calculated for each of the other points BQ C, D, E, F, G, and H.

As above, points A, B, C, D, , E, F, G, H
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 find the color densities of each grid point, dividing the cube at required intervals as shown in Figure 7. The combinations are determined by an appropriate method such as proportional allocation in the same manner as described above. Next, the combination of the color densities of each grid point determined in this way and the color densities of the object to be measured d (DR, Da,
DB) is selected such that the distance SA is the minimum. At the grid points selected in this way, the combination of the dot area ratios is already known, so the combination of the dot area ratios is the combination of the dot area ratios of the object to be measured P(c,
The dot area ratio input means (
7 is input. The dot area ratio input means is the same as in the first invention.

By the way, points A, B, C1D, E, as shown in FIG.
Determining the combination of color densities at all the grid points with the required precision for the entire area in F, G, )l requires a large number of grid points, making the processing difficult. Therefore, consider eight small solid bodies whose diagonal lines are the lines connecting the vertices, such as point P in FIG. In this way, the desired combination of color densities will be included in one of these small solids. Where it is included is determined by the combination d of color densities of the object to be measured (Da, DG, D
The determination is made based on which point B) is closest to the combination of color densities of vertices A to 1.

Once a small solid is determined in this way, the combination of color densities of each lattice point separated by the required precision is interpolated only for this small solid, and then the combination of color densities of each lattice point in this small solid is interpolated. Combination d (D
The grid point closest to R, DC, DB) may be selected.

In this way, the calculation time can be reduced to about one-eighth.

By considering this as being in the color density-dot area ratio conversion table, interpolation can be performed in exactly the same way as for the combination of C, M, and Y. Similarly, in the case of a combination of Bk, C, and Y, interpolation can be performed by considering that (bk, m, y) is passed through a G filter.

The halftone dot area ratio output means (70) outputs "the color information in the color information-dot area ratio conversion table and the color information of the object to be measured that completely match [and, if the color information corresponds to the matched color information]". A combination of dot area ratios is output, and if they do not match completely, a combination of dot area ratios interpolated as described above is output.

Note that the required halftone area ratio may be input using a numeric keypad or the like.

FIG. 9 is a flowchart showing an example of how the combination of halftone area ratios is determined using the apparatus according to the second invention of this application described above, when color density is used as color information. be.

FIG. 10 is an explanatory diagram of another interpolation method, and the RlG and B axes represent the color density obtained through the R, G, and B filters, respectively, with the color density combination t (Tu, Tc, TB) as the origin. It represents.

If the vector Bid (BR, BGSBB) is set here, BR=DR-TR, pc-'l'c for BG, and BB-to-DB-TB.

Furthermore, for each combination P (c, m, y,) of halftone area ratios corresponding to the combination t of color densities, 1 unit (
In other words, the combination Pa (C+10, m-10, y+L10) of the halftone dot area ratios that is shifted by 10% in the case of FIG. 2 is set, and the corresponding color density combination t3 (T old, T
G3, TB3) can be known from the color density-dot area ratio conversion table.

The dot area ratio P3 (C+10, m±1o', y±10
), vector B determines whether to take the positive or negative value.
It is determined depending on whether each component of td(BR, Bc, BB') is greater than or equal to zero or less than zero, and if it is greater than or equal to zero, it is considered a plus, and if it is less than zero, it is a minus. In this case, the amount to be applied to each of C+10, m+10, and y±10 is determined by the amount of each of Bn, BG, and BB.

can be expressed as a composition of several vectors.

Here, for the sake of simplicity, the following description will be made assuming that each component of the vector Btd is thicker than zero (.), but the same procedure can be applied even if this is not the case (.).

When the C component increases by 10% with respect to the combination of dot area ratios P (c, m, y), and when the C component and m
The combinations of dot area ratios when each component increases by 10% are R(c+10.m, Y) and P2, respectively.
(C+10, m+10, y).

The combinations of color densities corresponding to the combinations Pl and P2 of the dot area ratios are expressed as t 1 (TRI, TGl, TBI) and t 2 (, respectively) according to the color density-dot area ratio conversion table.
Ta2, TGl, TB2).

Therefore, the vector Btta is the vector old t11Bt+tz
π1□t3 by 1, Zuyama Jukoyama + Kameyama = πtt3 quality,
. t3K J: Jtt+-1-βBt+t2-1-
7”f, 2 l 3 = fftd.

Here, each component of the vector Btd (BRSBG, BB) is known as described above, so from the above relational expression,
! , win 1 ha.

Therefore, the combination d (DR, DG, DB) of the color densities of the object to be measured
) to the combination of color densities selected as closest to t
The combination of dot area ratios -tP' (do, m', zo) obtained by interpolating the combination of dot area ratios P (c, m, y) corresponding to
Since the table in the figure is at 10% intervals, c' = c + xl
0 m' = m + β x 10 y' becomes y-1-rXlo.

As described above, the combination of dot area ratios after interpolation P'(C'
, m', y') are determined.

Bektok: ``There are various ways to express a mountain as a composite of other vectors (2), so a vector of deviation may also be used.

However, in order to obtain a reasonable interpolation value, as shown in FIG. It is preferable to select

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

Furthermore, the interpolation of the dot area ratio can be performed in the same manner not only for color density but also for chromaticity.

As in the case of the first invention, various types of dot area ratio output means can be selected as appropriate, and in addition to layout scanners, for example, display devices such as CI (T display and printer) can also be selected. .

Since the present invention has the above structure, it has the following effects.

First of all, according to the device of the invention of this application, even if the color to be reproduced in printing is specified as an actual color, such as in a color sample, it can be done extremely easily and even without experience. In a short time, it is possible to determine the positive halftone dot area ratio of each color to reproduce the specified color.

Next, according to the apparatus of the invention of this application, the halftone dot area ratio of the halftone positive of each plate is always determined in a standardized form, unlike the conventional method, which is determined by humans. Quality control becomes easier.

Furthermore, according to the second invention of this application, in addition to the above-mentioned effects, it is possible to extremely easily determine the dot area ratio with the required accuracy.

Furthermore, according to the invention of this application, the amount of data stored in the first storage means (the amount of data is extremely small), and the comparison time and search time and interpolation time with the data stored in the second storage means are also significantly reduced. It is shortened to .

[Brief explanation of the drawing]

FIG. 6 is a conceptual diagram of the second invention Ω device, and FIGS. 9 and 9 respectively show flowcharts of an example of determining a combination of halftone dot area ratios using the apparatus of the second invention. (1)...Object to be measured (X))... -First storage means (20)...Color density measuring means (21)...Light source (22)...Filter (23)...Photoelectric conversion element c24)...Amplifier (25) ... Correction circuit (26) ... Logarithmic converter (Shu ... ~ converter (28) ... Display meter (3111) ...
・Second storage means (4))...Color density selection means (
50), (70)... Halftone area ratio output means (
60) ...Dot area ratio interpolation means patent applicant Figure 1 Figure 3 Figure 7 C Figure 8

Claims (2)

[Claims] (1) Color information and a halftone dot area in which at least one of the four colors Y, M, C, and Bk corresponding to the color information of the color separation plate of multiple colors includes a halftone dot area ratio of 0%. a first storage means in which a color information-dot area ratio conversion table indicating a correspondence relationship with a combination of ratios is stored; a color measurement means for measuring the color of the object to be measured and storing color information; a second storage means for storing color information determined by the color measurement means; and a second storage means for storing color information determined by the color measurement means;
The color information in the color information-dot area ratio conversion table stored in the storage means is compared with the color information of the object to be measured stored in the second storage means to determine the color information-dot area ratio. A color information selection means for selecting the color information closest to the color information of the object to be measured from among the color information in the conversion table, a halftone surface corresponding to the color information selected by the color information selection means, and a combination of rate. 1. A dot area ratio determining device comprising: a dot area ratio output means for outputting a dot area ratio. (2) Color information and a halftone dot area in which at least one of the four colors Y, M, C, and Bk corresponding to the color information of the color separation plate of multiple colors includes a halftone dot area ratio of 0%. a first storage means in which a color information-dot area ratio conversion table indicating a correspondence relationship with a combination of ratios is stored; a color measurement means for measuring the color of an object to be measured and storing color information; and the color The color information determined by the measuring means is stored (the second storing means and the first
The color information in the color information-dot area ratio conversion table stored in the storage means is compared with the color information of the object to be measured stored in the second storage means to determine the color information-dot area ratio. 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 conversion table; halftone area ratio interpolation means that determines a combination of ink types to be interpolated based on the color information and then determines a combination of interpolated halftone area ratios based on the color information/halftone area ratio conversion table; If the selected color information and the color information of the object to be measured do not match, the interpolation is performed. a halftone dot area ratio output means for outputting a combination of halftone dot area ratios corresponding to the selected color information if they match. Area ratio determination device.