JPH04260274A - Color separation device - Google Patents

Abstract

PURPOSE:To easily set color correction efficiently even when a kind of a color film used as an original is revised or whoever implements color correction in response to the color film. CONSTITUTION:Color correction data used for correcting picture data of a color film read by an input scanner 1 are stored in a hard disk 10 by a number in response to kinds of color films. When the color correction data in response to kinds of color films used actually among the color correction data are designated by a CRT terminal 11, the CPU 9 sets the designated color correction data to a lookup table for color conversion of a masking circuit 4. When scanning is implemented in this state, the picture data of the color film read by the input scanner 1 is corrected by the color correction data set in the lookup table of the masking circuit 4.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color separation device such as a color scanner used in a printing process.

0002

2. Description of the Related Art The printing plate-making process requires a color separation device for color-separating a document to be printed and usually obtaining a four-color plate. Conventionally, this color separation device reads a color document such as a color film with an input scanner, and converts the obtained image signal into a color correction section consisting of a LOG circuit, a highlight/shadow calibration circuit, a masking circuit, a color correction circuit, etc. The color correction circuit is configured to perform color correction based on each correction data set in a lookup table provided in each of the circuits.

[0003] The data set in each of the look-up tables is average fixed data, which remains unchanged even if the type of color film read by the input scanner changes. Therefore, by adjusting the data of the color correction circuit described above, the difference between the color reproduction characteristics (film characteristics) of each color film and the average color reproduction characteristics determined empirically can be adjusted. Obtains optimal color reproduction characteristics. Note that the color correction adjustment performed at this time is performed by, for example, adjusting a knob of a potentiometer, a rotary switch, or the like.

0004

[Problems to be Solved by the Invention] Therefore, in the case of the above conventional example, each time the type of color film changes,
It is necessary to manually reset the color correction data based on experience. In addition, if the color balance of the image on color film is disrupted due to insufficient exposure during camera shooting, or if changes need to be made to specific color components in the original document at the request of the client, the above-mentioned film types may be used. In addition to color correction due to changes,
You also need to set up color correction.

[0005] Therefore, these settings must be changed each time the type of color film is changed, which is a very complicated task, and requires experience as the above-mentioned delicate adjustments are required. Beginners may not be able to make adjustments. The present invention has been made to solve the above-mentioned problems, and even if the type of color film used as a color original is changed, anyone can efficiently and easily set color correction according to the color film. The purpose is to provide a color separation device that can perform color separation.

[0006]

[Means for Solving the Problems] The technical means of the present invention for solving the above problems reads a color original with an input scanner, and has a lookup table for color conversion of the image signal obtained by the input scanner. In a color separation device that performs color correction by supplying data to a color correction section equipped with a masking circuit, a plurality of color correction data having different color conversion characteristics depending on the film characteristics of a color film used as a color original are stored. a memory means; a data specifying means for specifying color correction data according to the film characteristics of the color film to be actually used from among the color correction data stored in the memory means; The apparatus is characterized by comprising a control means for reading color correction data from the memory means and setting it in the lookup table.

[0007] In addition to the plurality of color correction data, the memory means stores the product name or common name of the color film in association with the color correction data, and stores the product name or common name of the color film in association with the color correction data. The color correction data corresponding to the color film to be used may be read out by specifying a product name or a common name by the data specifying means.

[0008]

According to the first aspect of the present invention, color correction data for color correcting image data of a color film read by an input scanner is stored in the memory means in a number corresponding to the type of color film. When the data specifying means specifies color correction data corresponding to the type of color film (film characteristics) to be actually used from among these color correction data, the control means transfers the specified color correction data from the memory means. Read and set in the lookup table of the masking circuit.

When scanning is performed in this state, the image data read by the input scanner is color-corrected using the color correction data corresponding to the type of color film actually used, which is set in the look-up table of the masking circuit. Ru. In claim 2, when a product name or common name of a color film stored in the memory means in association with a plurality of color correction data is specified by the data specifying means, the specified color correction is performed. color correction data is set in the lookup table of the masking circuit, and image data read by the input scanner is processed based on the color correction data.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a color separation device according to the present invention. This device includes an input scanner 1 for reading color originals such as color film, a LOG circuit 2 to which image signals obtained by the input scanner 1 are sequentially applied, a highlight shadow calibration (HL/SD) circuit 3, and a masking circuit. 4. Color correction circuit 5.
It includes a UCA/UCR circuit 6, a gradation circuit 7, and an anti-LOG circuit 8. Furthermore, CP is added to each circuit 2 to 8.
It includes a CPU 9, a hard disk 10, and a CRT terminal 11 connected via a U bus 12.

The input scanner 1 is, for example, a drum-type input scanner, in which a cylinder carrying a color document is rotated around its axis, and a color document is picked up by a pickup unit using the three primary colors B, B, and B, which are additive colors. It is read as G and R image data and given to the LOG circuit 2. however,
As the input scanner 1, a flat type input scanner may be used.

[0012] The LOG circuit 2 logarithmically transforms the input signal, performs the logarithmic transformation via a lookup table provided therein, and sends the transformed data to the HL/SD circuit 3.
Output to. The HL/SD circuit 3 performs highlight adjustment and shadow adjustment, and after performing predetermined adjustments via a lookup table provided therein, provides the adjusted image data to the masking circuit 4.

The masking circuit 4 includes a lookup table for color conversion, and converts B, G, and R image data into Y and M as described later based on color correction data given to this lookup table. , C, and K are each converted into 8-bit data, and the converted image data is supplied to the color correction circuit 5. The color correction circuit 5 is for color correction, and after performing color correction via a lookup table provided therein, the corrected image data is sent to the U.
It is given to the CA/UCR circuit 6.

The UCA/UCR circuit 6 adds or removes the undercolor of the image, and outputs the processed image data to the gradation circuit 7. The gradation circuit 7 performs gradation processing, and outputs the processed data to the anti-LOG circuit 8. anti LOG
The circuit 8 inversely transforms the logarithmically transformed data in the LOG circuit 2 to return it to its original state, and outputs the inversely transformed data to an output scanner (not shown).

The hard disk (memory means) 10 stores data to be applied to look-up tables provided in the above-mentioned LOG circuit 2, HL/SD circuit 3, masking circuit 4, color correction circuit 5, etc.
Predetermined data is stored for each lookup table. As the color conversion data for the masking circuit 4, a plurality of different data are stored depending on the type of color film, that is, the film characteristics, as will be described later.

CRT terminal (data specification means) 11
is for manually specifying the color correction data stored in the hard disk 10. Operation panel (instead of CRT terminal 11)
keyboard) can also be used. The CPU (control means) 9 controls each of the above-mentioned circuits 2 to 8, and
When color correction data is specified on RT terminal 11,
The designated color correction data is read from the hard disk 10 and set in the lookup table of the masking circuit 4.

Next, color conversion by the masking circuit 4 will be explained. This color conversion is performed based on color correction data obtained from Equations 1 to 3 below. Note that these numbers 1 to 3 correspond to number 4 below.

[0018]

[Math 1]

[0019]

[Math 2]

[0020]

[Math 3]

[0021]

[Math 4]

The conversion characteristic fYB(
B), fMB(B), fCB(B), etc. differ depending on the type of color film. For example, in Figure 2 (
Compared to the case of using the standard color film shown in a), (b), and (c), when using a color film that emphasizes a certain color, for example, red, )
, (c), a function is used in which the output value (vertical axis) moves up and down as a whole for the same input value (horizontal axis).

Specifically, for the R image data shown in FIG. 3(a), fYR(R) and fMR(R) are approximately the same as in the corresponding FIG. 2(a). Yes, but f
CR(R) is high overall. Also,
Regarding the image data of G shown in FIG. 3(b), fYG(G) and fCG
(G) is slightly lower, and fMG(G) is higher. Regarding the image data of B shown in FIG. 3(c), fCB(B
) are almost the same, but fYB(B) and fMB(B) are slightly lower.

These conversion characteristics are determined by actually measuring color film samples using a densitometer. The input values (horizontal axis) in Figures 2 and 3 are
It corresponds to the image data output from the input scanner 1, and the output value (vertical axis) corresponds to each input value, and is on a logarithmic scale. Both figures show that the lower the output value, the more ink is used.

In other words, when using a standard color film, the data for the look-up table consists of 3 data for conversion to Y: fYB (B), fYG (G), and fYR (R).
Regarding the conversion to M, fMB(B), fMG(G),
Regarding the conversion of fMR(R) to C, fCB(B)
, fCG(G), and fCR(R), that is, 3×3, are prepared as one set. Also, when using other color films that emphasize red, a set of nine films is prepared.

[0026] In addition, in the case of color films having different characteristics from those described above, nine films are prepared for each type, the number of which corresponds to the number of types. Then, the prepared color correction data is stored in the hard disk 10 with each set of nine data associated with an identification number, for example. Selection of each set of color correction data is made by reading out the identification number by the CRT terminal 11. The read color correction data is displayed on the screen of the CRT terminal 11 and is also set in the lookup table of the masking circuit 4 via the CPU 9.

[0027] After setting the optimum color correction data in this way, the color original is actually scanned. When the input scanner 1 reads a color original, the read image data B, G, and R are sent to the LOG circuit 2 and the HL/SD circuit 3.
After being subjected to predetermined processing, the signal is input to the masking circuit 4. Here, Y, M,
It is converted as C, K image data. This converted image data is then sent to the color correction circuit 5, UC
A/UCR circuit 6, gradation circuit 7 and anti-L
The image is outputted via the OG circuit 8 to an output scanner (not shown), and a duplicate image is exposed and recorded.

Although the illustrated embodiment is as described above, the present invention can be modified in various ways as described below. In the above embodiment, the color correction section includes the LOG circuit 2, the HL/S
Although the configuration includes a D circuit 3, a masking circuit 4, a color correction circuit 5, a UCA/UCR circuit 6, a gradation circuit 7, and an anti-LOG circuit 8, the present invention is not limited to such a configuration. The present invention can be applied to a color correction section that includes at least the masking circuit 4.

Further, in the above embodiment, a plurality of color correction data are set in the lookup table provided in the masking circuit 4, and identification numbers are assigned in association with the color correction data.
However, the present invention is not limited to this, and the identification N
Instead of o, each set of color correction data may be stored in association with the product name or common name of the film, and the product name or common name may be specified on the CRT terminal (data specifying means) 11. Can be implemented. This has the advantage that data can be specified more easily and accurately than when using identification numbers.

[0030]

Effects of the Invention As explained above, according to the present invention, the type of color film used as a color document (
Color correction data of conversion characteristics according to film characteristics)
By specifying settings in the masking circuit's color conversion lookup table, anyone can perform color correction without the need for delicate manual adjustments like in the past.
And it can be done easily. Furthermore, in the past, when color correction was not performed accurately, it was necessary to perform color correction again, but this can also be prevented. Furthermore, if color correction data is specified using the product name or common name of the color film actually used, the work associated with color correction can be made easier and more accurate, and the operating rate can be improved. can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of a color separation device according to the present invention.

FIG. 2 is a color conversion characteristic diagram of a standard color film, in which (a) shows the characteristic fYR(R
), fMR(R), fCR(R), and (b) shows the characteristics of G image data fYG(G), fMG(G),
fCG(G) is shown, and (c) is a diagram showing characteristics fYB(B), fMB(B), and fCB(B) for B image data.

FIG. 3 is a color conversion characteristic diagram of a color film in which red is emphasized; (a) is a characteristic fY for R image data;
R (R), fMR (R), fCR (R) are shown, (b)
are the characteristics fYG(G), fMG(
G), fCG(G), and (c) shows the characteristics fYB(B), fMB(B), fCB(B) for the image data of B.
FIG.

[Explanation of symbols]

1... Input scanner 3... Highlight shadow calibration circuit 4... Masking circuit 5... Color correction circuit 6... UCA/UCR circuit 7... Gradation circuit 9... CPU (control means) 10... Hard disk (memory means)

Claims (2)

[Claims] [Claim 1] Read a color original with an input scanner,
Film characteristics of a color film used as a color original in a color separation device that performs color correction by feeding an image signal obtained by an input scanner to a color correction unit equipped with a masking circuit having a lookup table for color conversion. a memory means storing a plurality of color correction data having different color conversion characteristics according to the color change; and a color according to the film characteristics of the color film actually used from among the color correction data stored in the memory means. It is characterized by comprising a data designation means for designating correction data, and a control means for reading out the color correction data designated by the data designation means from the memory means and setting it in the lookup table. color separation device. 2. The memory means stores, in addition to a plurality of color correction data, a product name or a common name of a color film in association with the color correction data, and stores the product name or common name of a color film in association with the color correction data, and stores the product name or common name of a color film in correspondence with the color correction data, 2. The color separation apparatus according to claim 1, wherein the color correction data corresponding to the color film to be processed is read out by specifying a product name or a common name by the data specifying means.