JPS60259903A - Detecting device of percentage dot area - Google Patents

Abstract

PURPOSE:To select the nearest color information from a color information/screen dot area percentage conversion table, by, for expressing with ink of each color Y, M, C, considering a BK plate with a color information selecting means, after the finished process of a color information correcting means. CONSTITUTION:A color informtion selecting means 40 compares color imformation of a specimen stored in the second memory means 30 with that in a color information/screen dot area ratio conversion table stored in the first memory means 10 to select the nearest information to that of a specimen from the color information/screen dot area ratio conversion table. For this selection, in case when, for instance, a color density is adopted as a color information, the combination of the minimum distance SA(n) between the color density obtained through R, G, B filter respectively of the specimen and the n-th density as that in the color information/screen dot area ratio conversion table is obtained. The value (n) at which the distance SA(n) takes the minimum value coincides with that of n where [SA(n)]<2> takes the minimum value. Accordingly, detection by changing the values of n from n=1 to the last determines the value of n at which SA(n) takes the minimum value and a combination of screen dot area ratios of each corresponding plate.

Description

DETAILED DESCRIPTION OF THE INVENTION Conventionally, in order to create printed matter, image information is captured from a color original, and C (cyan), M (magenta), Y (yellow), and Bk (black) are used for printing based on the image information. ) Calculate the halftone dot area ratio of each plate and output a halftone film for each dose, or make a gravure printing plate by engraving it using a mechanical engraving method, laser engraving method, etc. for each 40-plate printing plate. I don't know the device that creates it,
ing. In such a device, image information is stored in a single storage device, and the arrangement of the images can be freely set, and furthermore, the color of a part or a specific part of the image can be modified or changed, or There are some devices on the market that can arrange specified colors in specified areas in specified shapes. 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 or setting the color of a certain part in a device such as the layout scanner, a color to be changed or a color to be set may be specified. In such a case, the color cannot be specified using the dot area ratio, and there is no problem if you just key in the value. However, a problem arises when colors are specified using color samples.

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

For example, let's say that a printing sheet comes with a large number of color samples attached to specify the color.For example, if you want to uniformly fill the background with a certain color, you can create a small piece of paper with the color of the background. Assume that it is attached as a color sample.

If you specify the same color as this color sample, but if you want to print the same color, use this color sample and 10% The halftone area ratio of each printing plate is printed by changing the halftone area ratio to match the spacing, and the one that is most similar is selected by visual comparison with the color chart. It is common to decide whether the percentage is in units of percentage or not based on the fact that it is written on a color chart and input it into the device. However, this method takes time to compare, and the colors selected from the color chart vary depending on the person, making it difficult to decide.
The disadvantage is that the dot 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 are currently on the market that can calculate the dot area ratio by measuring the density of the object to be measured. In this densitometer, the measured density value is processed by a microcomputer built into the densitometer to calculate the 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 only applies to colors that have a standard density.

Usually used only for single colors. Moreover, the aforementioned Neil
Nielsen's equation ideally reproduces halftone dots without dot gain, and is established by appropriately setting coefficients that vary depending on factors such as screen frequency, density, and paper transparency. Even if it is a single color, it is not possible to accurately obtain a wide range of dot area ratios from the lychee area to the shadow area. Furthermore, it is completely 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, the densitometer that has been known since 1995 has a halftone dot area ratio of Y to express the color of the color sample for the following reason.
, M, C, and 13 cannot be displayed in combination for each version. 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, and One example of medium pressure C ink is that it contains an M component and a Y component. Since the printing inks of Y, M, and C actually used are not ideal, the colors of objects to be measured such as color samples are changed to B (blue violet) and G (which are complementary colors of Y, M, and C). Even if you calculate the dot area ratio using the Niel-Nielsen formula from the density values measured through the R (green) and R (red) filters, the value will be lower than the actually required Y. ,M.

It does not show the dot area ratio of each screen in C.

This will be more clearly understood by the following example.

For example, it is easier 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. Each of these prints? ``If you calculate the density through the LRLR filter and the B filter, it is 153.
0.52.0.17, but these values are R,
It is clear that it cannot be used to calculate the halftone area ratio of C, M, and Y plates, which are complementary colors to G and H.

This 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 reproduce the colors of a color sample or to determine the dot area ratio of a printing plate for each color.

The present invention eliminates the above-mentioned various drawbacks, and any color can be converted into Y, M, C color ink or Y
, M, and C0Bk, the apparatus is capable of easily determining how to combine the dot area ratios of the respective color plates.

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 α0) 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; Bk
B showing the correspondence between the halftone area ratio of the color separation plate and color information.
The color information data determined by the color measurement means (201) that stores the 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 is as follows:
For example, the color density of the object to be measured is obtained through each of the R filter, G filter, and B filter.
It is a set of combinations of different color densities, or chromaticity. Next, the color information selection means (40) uses the color information of the color information-dot area ratio conversion table stored in the first storage means αO) and the color information stored in the second storage means (30). Compare the color information of the object to be measured or the color information considering the Bk version described later, and consider the color information of the object to be measured or the Bk version described later from among the color information of the color information-dot area ratio conversion table. Select the color information that is closest to the color information.

On the other hand, the color information correction means 150) is the Bk version amount setting means (7C
1) The color information stored in the second storage means example and the first storage means θO) based on the conditions set by v)
The dot area ratio of the Bk plate is determined from the Bk plate calculation data stored in the Bk plate calculation data, and the color information corresponding to the dot area ratio of the Bk plate is stored in the second storage means (30). This subtracts the color information from the existing color information to obtain color information that takes the Bk version into consideration.

In this case, the process by the color information correction means (5o) is to select the color information closest to the color information stored in the second storage means (30) by the color information selection means (401), The calculation may be performed after determining the conditions for the Bk plate calculation based on the results, or the conditions for the Bk plate calculation may be determined and the color information selection means (401
It is also possible to perform the processing by the color information correction means (501) before the processing by the color information correction means (501), and it is convenient to be able to switch which one to perform.

As described above, after the process in the color information correction means (5) is completed, the color information selection means (40) selects the color information that is closest to the color information considering the Bk plate. Selected from the conversion table.

The Bk plate amount setting means (n) arbitrarily sets the amount of Bk plate to determine how much Bk plate should be added when printing with Bk plate added to Y, M, 'C color. It is provided so that the halftone dot area ratio can be calculated by changing it.

Here, the Bk plate amount refers to the percentage of gray components included in the color information of the object to be measured that is replaced with the Bk plate, the density value based on the concept of judgment UCR, or the amount of gray that is not used during printing. The halftone area ratio value of the Bk version may also be used.

Specifically, the Bk version amount setting means (7D) includes a keyboard or similar input means for inputting the Bk version amount, and further includes a color information modifying means (if the condition set to 50 is the color density). It is equipped with an instruction key for instructing whether there is a dot area ratio or a halftone dot area ratio.

In this way, the combinations of halftone area ratios corresponding to the color information selected by the color information selection means +4f11 are interpolated by the interpolation means as necessary, and then the halftone area ratio output means ( b)) 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.

FIGS. 2(a) and 2(b) show 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, On the left side, the combinations of color densities obtained through the R, G, and B filters are shown, and on the right, the Y, M, and C colors corresponding to the combinations of color densities shown on the left are shown. Combinations of dot area ratios of six color separations 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 C0, the halftone area ratio % ~ ioo
% at appropriate intervals, for example at 10% intervals as in the case of FIG. 2, and actually prints to create a color chart. That is, in the example of FIG. 2, numbers 1 to 11 are M and Y.

The plates have a halftone dot area ratio of 0%, and only the 0 plate is changed in 10% increments between 0% and 100%, and numbers 12 to 22
Until now, the halftone area ratio for Y0 clothing was 0%, and the halftone area ratio for the M version was 1.
0%, and only the 0 version was changed in 10% increments between 10% and 100%.Hereinafter, various combinations were made in which the halftone area ratio of each version of Y, M, and C was changed at 10% intervals. Create a color chart. Such a combination is Y.
When the halftone dot area ratio is changed at 10% intervals for each of the M and C versions, 113=1331 combinations are generated.

For each color of the color chart created as described above, determine the combination of color densities obtained through the R filter, G filter, and B filter.

As described above, a color density-dot area ratio conversion table is created that shows the correspondence between combinations of color densities and corresponding combinations of halftone area ratios of plates of each color for various colors.

Further, FIG. 3 shows the dot area ratio and RlG of the Bk plate as an example of the Bk plate calculation data stored in the first storage means.
, B is a table showing the correspondence relationship with color density through each filter.

Similarly to the creation of the color density-dot area ratio conversion table, the dot area ratio of the Bk plate is changed in 10% increments in advance, and after the actual printing is carried out, it is passed through the RlG and B filters. It is obtained by measuring the color density.

The data for calculating the k version may not be in the form of a table as shown in FIG. 6, but may be in the form of a data function of the table.

Note that the above-mentioned R, G, and B. Although it is common to measure the density of one color using each filter, an interference filter or the like having a peak in the absorption part of the spectral reflection curve of printing ink may be used. The same filter used to create the color density-dot area ratio conversion table must also be used when measuring the color density of the object being measured.

Looking at the color density-dot area ratio conversion table obtained as above, for example, in numbers 1 to 11 in Fig. 2, the dot area ratio of each plate of M and Y is 0%. No change C
R is a complementary color to C even though only the version has changed.
Not only the color density through the filter, but also other G, B.

The color density through each amber filter also changes.

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

This relationship holds true for other inks as well, and they contain other components. 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 and the data for Bk plate calculation are stored in the first storage means 00) (however, such storage means may be a magnetic disk, a floppy disk, a ROM, etc. as appropriate). The following are used.

As described above, the first storage means α0) stores in advance the color information to halftone area ratio conversion table and the Bk plate calculation data.

Further, the color measuring means (20) measures the color of the object to be measured to obtain color information, and FIG. 5 is a block diagram showing one embodiment thereof. The example in FIG. 5 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 irradiated by a light source (211).
The reflected light is input to a photoelectric conversion element 3) via a filter (22), where it is converted into an electrical signal. The filter (221 is the same one used to create the color density-dot area ratio conversion table, and three types of filters, R filter, G filter, B filter, etc.) can be converted. In this case, the filter can be changed either electrically or manually.

In addition, in the example shown in Fig. 5, the light from the light source is diagonally 45
Although the light is emitted from an angle of 45° and received directly above, it is also possible to emit light from directly above and receive the light at an angle of 45°.

The electrical signal generated by the photoelectric conversion element (c) is amplified by the amplifier root, subjected to necessary correction by the correction circuit (25), and subjected to logarithmic conversion processing by the logarithmic converter (26). The analog signal is converted into a digital signal by the D converter (2η) and the color density as color information is stored in the second storage means (3
01, it will be stored. The electric signal value can be checked on the display meter (2al).

The display meter (2→ may be an A/D converter (2η) followed by a digital display).

As described above, the object to be defined 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 C1m, an appropriate one such as a RAM can be selected.

The color information selection means (41, 11 includes the color information of the object to be measured stored in the second storage means II+ and the color information stored in the first storage means (10) - halftone area ratio conversion) The method compares the color information in the table and selects the color information in the color information-dot area conversion table that is closest to the sensuality of the object to be measured.The selection is made as follows. For example, when color density is used as color information, the color density obtained through each of the R filter, G filter, and B filter of the object to be measured is DR, f).
a, DB, and the R filter, G filter, and B at the nth number of the color density-dot area ratio conversion table as a color information-dot area ratio conversion table.
The color density through the filter is T R (n),
T o (11, Tn(n). Next, the combination of color densities of the object to be measured DR, DG, D s and the nth color density of the color density-dot area ratio conversion data The combination T n(nLTG(nl, Ts(n10) of the color density combination T that minimizes the distance 5A (nl) at the number
Find R(nl, To(n), TB(n)).

Distance 5Jn) is [:5Afnl]2=CTR(n)-DRI) +[T
oin)-Do]2+CT day (nl-DRI2).

The value of the distance S A' (l for which nl is the minimum) is CS A (
nl) 2b - Stay silent with the minimum value of n. Therefore, using the upper wheel relation, change the value of n sequentially from n = 1 to the last combination of color densities in the color density-dot area ratio conversion table that minimizes CS A (n) ] 2. By doing a search, you can find the value of n that minimizes SA(n).

The combination of color densities in the color density-dot area ratio conversion table corresponding to nK that minimizes 5A(n) is determined as the one closest to the combination of color densities of the object to be measured, and the combination of color densities is matched. The combination of dot area ratios for each of the Y, M, and C versions has not been determined.

In this case as well, if GSA, (n)] 2
If becomes zero during the search, that is, if during the search a combination of color densities of the object to be measured and the color density in the color density-dot area ratio conversion table are found to match, υ Since this data indicates the combination of halftone area ratios corresponding to the combination of color densities at the next value of n, subsequent searches may be discontinued.

Although the color information is selected in the above manner, the same process may be performed when chromaticity or the like is employed in addition to color density as the color information.

The combination of dot area ratios of the Y, M, and C versions determined as described above is outputted by the dot area ratio output means (60). The dot area ratio output means is for outputting the determined dot area ratio, and can employ a display, a glintter, 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 125th color density is selected as the closest color density to the combination of color densities obtained by measuring the object to be measured, then from the table in Figure 2, the 0 version is 30%, the M version is 0%, The Y version is output as 10% by the dot area ratio output means.

By the way, it is well known that depending on the combination of dot area ratios output in this way, a portion of them can be replaced with 7Bk ink.

Originally, the Bk version is used to compensate for the lack of density in a part of the shadow, so it is only necessary to use it from the middle to the shadow. This is called skeleton black. However, from the theory of color reproduction,
The Bk version can be used in various formats, starting from skeleton black, limiting the number of 3-color versions as much as possible, and increasing the number of Bk versions (all the way to full black).
There are many combinations in which the amount of six-color plates can be appropriately varied depending on the plate format, and the printed results can be exactly the same. FIG. 6 shows tone reproduction curves for skeleton black and full black, and various types of intermediate black curves can be taken between them.

Figure 7 is an explanatory diagram of the format of the Bk version, and Figure 7A (a)
This table shows what combinations of three-color plates should be used when changing the format of the Bk plate to reproduce a certain type of brown as shown in the figure. Figure 7A (as shown in bl) (If you use skeleton black, the Bk plate is not used at all, but if you use full black as shown in Figure 7A (c), the density of the 0 plate, which is the lowest density plate) has been replaced with the Bk version.

Further, FIG. 7A(d) shows an example in the case of intermediate black. FIG. 7B is an explanatory diagram of another example of the Bk version format. Figure 7B (cl) and Figure 7B (d) respectively show the case where full black and medium black Bk plates are adopted.

Among these various Bk version formats, which format to use can be arbitrarily set or changed, and this setting or change is performed by the Bk version amount setting means (70).

Next, a search is made to find out which of the densities corresponding to the C0M and Y versions measured through the R, G, and B filters has the lowest value. If you look at FIG. 7 A (al) of the brown example in FIG. 7, the C density is the lowest value. How much of this density is to be replaced with the Bk plate is determined by the Bk plate amount setting means (70). This is based on the concept of so-called UCR, and if it is full black (UC, R value is set to Replace a certain proportion of C density in the Bk version with black (0<x(100) or skeleton black (X20).If the density of the C version replaced with this Bk version is R, then BR=C density xx/1o .

becomes.

Next, using the Bk plate calculation data stored in the first storage means, the required dot area ratio of the Bk plate is determined. Examples of the data for calculation of the blackout plate are shown in FIGS. 3 and 4. In FIG. 4, the horizontal axis is the Bk dot area ratio, and the vertical axis is the density measured through the R, G, and B filters.

The dot area ratio of the Bk version can be determined by finding the intersection between the density BR to be replaced with the Bk version obtained above and the density measured via the R filter, and reading the value on the horizontal axis at that point. . In this determined Bk plate halftone area ratio,
By reading the densities through the B and G filters, the M version to be replaced with the Bk version and the densities BG and BB of the M version can be determined.

In addition, the halftone dot area ratio of the Bk plate is inputted from the Bk plate size setting means (70), and this is set as a condition for using the Bk plate.Since the halftone dot area ratio is already known, as shown in FIG. , B at this halftone area ratio based on the relationship shown in FIG.
, G, By reading the concentration through the R filter, B
C version, M version, density BR, Bo of M version replaced with k version,
13n can be added.

Next, add the density values of the remaining versions that are not replaced with the Bk version, D 'R1D' (1, D
'B is determined by the following formula.

D'R=DR-BR p'G= Do -13°D'B2ice -f3n 11 Note that DR, DG%DB are the concentrations of the object to be measured through R, G, and B filters, RR, BG , BB is the density of each. D'R, D'G
, D'B is color information considering the Bk version when color density is adopted as color information.

The same thing can be done when using chromaticity or other information other than color density as color information.

Using the color information in consideration of the Bk version determined as described above, the color information selection means selects the color information closest to the color information in consideration of the Bk version in the color information-dot area ratio conversion table. Choose from among them.

The combination of dots and dot areas corresponding to the color information thus selected and the dot area ratio of the Bk plate are determined by the dot area ratio output means (
60).

The above-mentioned processing is performed using the Bk version amount setting means (70).
It is desirable to repeat the process by changing the amount of plates in various ways.
This makes it possible to determine an appropriate halftone area ratio.

Note that the color information closest to the color information stored in the second storage means is selected from the color information-dot area ratio conversion table, and the Bk version is determined according to the result of calculating the dot area ratio corresponding to the color information. In some cases, a combination of halftone area ratios is selected taking into consideration the color information, and in such a case, the color information is selected by replacing the color information stored in the second storage means with color information that takes the Bk version into consideration It is sufficient to perform processing by means.

Printers, display tubes, CR
A display device such as a T display can be employed.

In addition, the determined dot area ratio may be output to a data storage medium such as a floppy disk, magnetic tape, or paper tape in order to be inputted to an external device such as a layout scanner, or it may be output directly to an external device. good.

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 conversion table is created.

In the example shown in FIG. 2, the dot area ratio is changed at 10% intervals, so the accuracy does not increase beyond 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 becomes 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.

It is preferable to perform interpolation in order to eliminate such drawbacks and determine the halftone dot area ratio at intervals finer than the data interval of the halftone dot area ratio in the color information-halftone dot area ratio conversion table. 58-81560, and since it is not the subject matter of the present application, its explanation will be omitted.

FIG. 8 shows a flowchart showing how the dot area ratio is determined in the present invention.

Since the present invention has the above-described configuration, 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, such as a color sample, is not specified as an actual color, it is extremely easy to use even if you are not an experienced person. Moreover, it is possible to reproduce the designated color and determine the halftone dot area ratio of the halftone positive chip of each color in a short time.

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 the quality of printed matter can be controlled. becomes easier.

Furthermore, when considering the Bk plate, it is possible to arbitrarily set the amount of Bk plate for one object to be measured and repeatedly calculate the halftone area ratio, and print in 6 colors of Y, M, and C. Is it better to do it? Or Y, M, C.

Is it better to print in 4 colors of Bk? In that case, B
It is possible to determine how much k-plate should be used, which is very convenient for use in actual printing work.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram of the device of this invention, Figures 2 (a) and (b)
) is an explanatory diagram of a color density-dot area ratio conversion table, Figure 3 is a table as an example of Bk plate calculation data, Figure 4 is a graph by a function as an example of Bk plate calculation data, FIG. 5 is a block diagram of one embodiment of the color measuring means;
The figure shows tone reproduction curves for skeleton black and full black, Figures 7A and 7B are explanatory diagrams of the Bk plate format for brown and black colors, respectively, and Figure 8 shows halftone dots obtained using the apparatus of the present invention. It is a flowchart of an example in the case of determining a combination of area ratios. (10)...First storage means (20)...Color information measurement means (30)...Second storage means (40)...
・Color information selection means (50)...Color information modification means (7
0)...Bk plate capacity setting means Patent applicant Edition Printing Co., Ltd. Representative Kazuo Suzuki Engraving of the drawing (no change in content) Figure 1 Figure 5 Figure 3 Figure 4 Figure 6 Figure 0, i! Q(7Mt'P)5%M -7th (ω)(b) (Q-n (b) CI-IY CMYek O Y Ink Procedural Amendment (Hokoma October 23, 1981 Patent Application No. 115770 2, Title of Invention Halftone Area Ratio Determining Device 3, Relationship with the Person Who Makes the Amendment Case Patent Applicant) Address: 1-5-1-5 Taito, Taito-ku, Tokyo Subject of amendment a) Application opening) Specification c) All drawings 6, Contents of amendment

Claims (1)

[Claims] Color information-dot area ratio conversion that indicates the correspondence between the 11 color information and the combination of the dot area ratios corresponding to the color information of the three color separation plates of Y, M, and Cf. a first storage means storing a table and BK plate calculation data indicating a correspondence relationship between the halftone dot area ratio of the BK color separation plate and color information; a second storage means for storing the color information obtained by the color measurement means, and a second storage means for storing the color information obtained by the color measurement means; BK plate amount setting means for arbitrarily setting the halftone area ratio of the BK plate, and once the amount of gray component to be replaced with the BK plate is set by the BK plate amount setting means, Calculating the halftone dot area ratio of the BK plate from the color information stored in the second storage means and the BK plate calculation data stored in the first storage means, and corresponding to the halftone dot area ratio of the BK plate. Either the color information that takes the BK version into consideration is obtained by subtracting the color information stored in the second storage means from the color information stored in the second storage means, or the halftone area ratio of the BK version is determined by the BK version amount setting means. If set, a color information correction means subtracts the lust axis corresponding to the halftone dot area ratio of this BK version from the color information stored in the second storage means to obtain color information taking the BK version into consideration. Then, the color information-dot area ratio conversion table stored in the first storage means is compared with the color information stored in the second storage means or the color information considering the BK plate. The color information -
color information selection means for selecting the color information stored in the second storage means or the color information in consideration of the BK plate from among the color information in the halftone ratio conversion table; and the color information; A dot area ratio determining device comprising a dot area ratio output means for outputting a combination of dot area ratios corresponding to the selection means and a dot area ratio of the BK plate. (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 information-dot area ratio conversion table. A dot area ratio determination device according to claim 1, characterized in that: