JP2001275004A - Color converting processor and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speed up color conversion processing. SOLUTION: The color converting processor has a density data input part 1 which inputs data in 1st image format, a memory 2 which stores the values of pixels inputted by the density data input part 1, a 1st color conversion part 3 which performs color conversion processing for pixels less than the pixels stored in the memory 2 to data in 2nd image format, a 2nd color conversion part 4 which performs color conversion processing for the pixels other than the pixels converted by the 1st color conversion part 3 to data in the 2nd image format by using the values of the pixels stored in the memory 2 and the values converted by the 1st color conversion part 3, and an output part 5 which outputs the values obtained by the color conversion of the 1st color conversion part 3 and 2nd color conversion part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color scanner,
The present invention relates to a color conversion processing technology used for a color printer, a color monitor, and the like, and particularly to a technology that is effective when applied to a color conversion process for performing color conversion from data in a first image format to data in a second image format.

[0002]

2. Description of the Related Art Conventionally, three-dimensional lookup is performed to perform color conversion from data of a first image format (for example, RGB image density data) to data of a second image format (for example, CMY or CMYK image print data). A table reference method and a 3 × 3 masking operation method have been proposed.

Hereinafter, a conventional color conversion technique based on a three-dimensional lookup table reference method will be described with reference to FIGS. 2 and 3. FIG.

FIG. 2 is a flowchart showing a color conversion process in the color conversion processing device, and FIG. 3 is an explanatory diagram showing a reference lookup table used for the color conversion process in the color conversion processing device. In FIG. 3, the look-up table contains 0, which is the input value of Dr, Dg, Db.
It is composed of 9 × 9 × 9 grid points obtained by equally dividing 8-bit data of up to 255 into 8 bits, and all values between the grid points are 32 (= 2 to the fifth power).

In the color conversion process, first, in FIG.
RGB image density data dr, dg, db are input (step 1), and upper 3 bits X, Y, Z and lower 5 bits x, y, z are extracted from the input dr, dg, db. (Step 2) (Step 3).

Next, the extracted upper three bits X,
From Y and Z, Dr.Dg.Db-C.M.Y shown in FIG.
, The values P0 (X, Y, and 8) of eight points of Dr. Dg. Db which are RGB image density data
Z), P1 (X, Y, Z + 1), P2 (X, Y + 1,
Z), P3 (X, Y + 1, Z + 1), P4 (X + 1,
Y, Z), P5 (X + 1, Y, Z + 1), P6 (X +
C, M, CMY image print data corresponding to P1, (Y + 1, Z) and P7 (X + 1, Y + 1, Z + 1).
-8 points Q0 (C0, M0, Y0) and Q1 of Y and K
(C1, M1, Y1), Q2 (C2, M2, Y2), Q
3 (C3, M3, Y3), Q4 (C4, M4, Y4),
Q5 (C5, M5, Y5), Q6 (C6, M6, Y
6), Q7 (C7, M7, Y7) is extracted (step 4).

Further, Q0 to Q7, which are the values of C, M and Y,
Weighting coefficients H0 to H7 for the eight points
= (32-x) × (32-y) × (32-z), H1 =
xx (32-y) x (32-z), H2 = (32-x)
× y × (32-z), H3 = x × y × (32-z), H
4 = (32−x) × (32−y) × z, H5 = xx × (3
2-y) × z, H6 = (32−x) × y × z, H7 = x
× y × z (step 5).

Then, the values of C, M, and Y corresponding to the input values dr, dg, and db are changed to Q0 to Q7 and H0 to
It is obtained by (Equation 1) using H7 (step 6).

When the processing from step 1 to step 6 is performed on all the pixels, the color conversion processing ends.

(Equation 1) C = {(Ci × Hi)} (32 × 32 × 32) M = {(Mi × Hi)} (32 × 32 × 32) Y = {(Yi × Hi)} (32 × 32 × 32)

[0011]

However, in the prior art, since the interpolation processing is performed with reference to the look-up table for each pixel of the input image, processing time is required.

Accordingly, an object of the present invention is to provide a color conversion processing technique that can speed up the color conversion processing.

[0013]

In order to solve this problem, a color conversion processing apparatus according to the present invention comprises: an input unit to which data of a first image format is input; and a plurality of pixels input by the input unit. , A first color conversion unit that performs a color conversion process on a smaller number of pixels than the number of pixels stored in the memory into data of a second image format, and a memory stored in the memory. For the pixels for which the color conversion processing has not been performed in the first color conversion unit among the pixels, a pixel using the values of the plurality of pixels stored in the memory and the values color-converted by the first color conversion unit is used. A second color conversion unit that performs a color conversion process on the data of the second image format, and an output unit that outputs a value color-converted by the first color conversion unit and the second color conversion unit. Things.

This makes it possible to speed up the color conversion process.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to an input unit to which data of a first image format is input, and a memory for storing a plurality of pixel values input by the input unit. A first color conversion unit that performs a color conversion process on the number of pixels smaller than the number of pixels stored in the memory into data of the second image format, and a first color conversion unit among the pixels stored in the memory. For pixels for which color conversion processing has not been performed by the color conversion unit, data of the second image format is converted into data of the second image format using the values of a plurality of pixels stored in the memory and the values color-converted by the first color conversion unit. The color conversion processing device includes a second color conversion unit that performs a color conversion process, and an output unit that outputs a value that is color-converted by the first color conversion unit and the second color conversion unit. Has the effect that it is possible to increase the speed.

According to a second aspect of the present invention, in the first aspect, the data stored in the memory is:
This is a color conversion processing device that is a pixel on the same line or a pixel on a plurality of lines, and has an effect that the speed of the color conversion process can be increased.

According to a third aspect of the present invention, a step of inputting data of a first image format, a step of storing values of a plurality of input pixels, and a step of storing a number smaller than the number of stored pixels Performing a color conversion process on the pixels of the second image format into data of the second image format; and, for the pixels that have not been subjected to the color conversion process among the stored pixels, the stored values of the plurality of pixels and the color A recording medium storing a program for executing a step of performing a color conversion process on the data of the second image format using the converted value and a step of outputting the color-converted value; Has the effect that it is possible to increase the speed.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG.

FIG. 1 is a block diagram showing a color conversion processing device according to an embodiment of the present invention, FIG. 2 is a flowchart showing color conversion processing in the color conversion processing device, and FIG. FIG. 4 is an explanatory diagram showing a reference lookup table used, FIG. 4 is an explanatory diagram showing an example of a color conversion process in a second color conversion unit of the color conversion processing device of FIG. 1, and FIG. 5 is a diagram of the color conversion processing device of FIG. FIG. 6 is an explanatory diagram showing another example of the color conversion process in the second color conversion unit, and FIG.
FIG. 7 is an explanatory diagram showing still another example of the color conversion processing in the second color conversion unit of the color conversion processing device of FIG. 1, and FIG. 7 is an explanatory diagram showing a specific development example of the color conversion processing device of FIG.

As shown in FIG. 1, a color conversion processing apparatus according to the present embodiment includes a density data input section (input section) 1 for inputting RGB image density data (data of a first image format), A memory 2 for storing density data of a plurality of pixels input by the data input unit 1, and CMY or CMY for pixels smaller than the number of pixels stored in the memory 2.
A first color conversion unit 3 for performing a color conversion process on MYK image print data (data of a second image format);
Of the pixels that have not been subjected to the color conversion processing by the first color conversion unit 3 among the pixels stored in the memory 2, the density conversion of a plurality of pixels stored in the memory 2 and the color conversion by the first color conversion unit 3 Second color conversion unit 4 that performs a color conversion process using the obtained value
And an output unit 5 that outputs a value that has been color-converted by the first color conversion unit 3 and the second color conversion unit 4.

Here, the number of pixels stored in the memory 2 is 2
The case of the number will be described.

First, when RGB image density data dr, dg, db is input to the density data input unit 1, the input density data of the two pixels is stored in the memory 2.

The first color conversion unit 3 performs a first color conversion process on the density data 6A of the first pixel among the two density data stored in the memory 2. The first
The details of the color conversion processing will be described later.

Next, of the two density data stored in the memory 2, the second color conversion unit 4 applies the second color conversion unit 4 to the density data 6 B of the pixel that has not been subjected to the first color conversion processing. Perform color conversion processing. The details of the second color conversion processing will also be described later.

Next, the first color conversion processing will be described in detail with reference to FIGS.

From the RGB image density data, CMY or C
As the first color conversion processing for converting to MYK image print data, a description will be given of a three-dimensional lookup table reference method from among a three-dimensional lookup table reference method, a tetrahedral interpolation method, a 3 × 3 masking operation method, and the like. I do.

FIG. 2 is a flowchart showing a color conversion process using a three-dimensional lookup table reference method, and FIG. 3 is a diagram showing RGB image density data Dr (red density data), Dg (green density data) and Db.
FIG. 8 is an explanatory diagram showing a reference lookup table from (blue density data) to C (cyan), M (magenta), and Y (yellow), which are CMY image print data. In addition,
In FIG. 3, the lookup tables are Dr, Dg,
It is composed of 9 × 9 × 9 grid points obtained by equally dividing 8-bit data of 0 to 255, which is the input value of Db, into eight, and all the values between the grid points are 32 (= 2 to the fifth power). Has become.

In the color conversion process, first, in FIG.
RGB image density data dr, dg, db are input (step 1), and upper 3 bits X, Y, Z and lower 5 bits x, y, z are extracted from the input dr, dg, db. (Step 2) (Step 3).

Next, the extracted upper three bits X,
From Y and Z, Dr.Dg.Db-C.M.Y shown in FIG.
, The values P0 (X, Y, and 8) of eight points of Dr. Dg. Db which are RGB image density data
Z), P1 (X, Y, Z + 32), P2 (X, Y + 3)
2, Z), P3 (X, Y + 32, Z + 32), P4 (X
+32, Y, Z), P5 (X + 32, Y, Z + 32),
P6 (X + 32, Y + 32, Z), P7 (X + 32, Y
+32, Z + 32), C, M, Y, K values of eight points Q0 (C0, C0,
M0, Y0), Q1 (C1, M1, Y1), Q2 (C
2, M2, Y2), Q3 (C3, M3, Y3), Q4
(C4, M4, Y4), Q5 (C5, M5, Y5), Q
6 (C6, M6, Y6) and Q7 (C7, M7, Y7) are extracted (step 4).

Further, Q0 to Q7 which are the values of C, M and Y
Weighting coefficients H0 to H7 for the eight points
= (32-x) × (32-y) × (32-z), H1 =
xx (32-y) x (32-z), H2 = (32-x)
× y × (32-z), H3 = x × y × (32-z), H
4 = (32−x) × (32−y) × z, H5 = xx × (3
2-y) × z, H6 = (32−x) × y × z, H7 = x
× y × z (step 5).

Then, the values of C, M, and Y corresponding to the input values dr, dg, and db are changed to Q0 to Q7 and H0 to
It is obtained by (Equation 1) using H7 (step 6).

When the processing from step 1 to step 6 is performed for all the pixels, the color conversion processing ends.

(Equation 1) C = {(Ci × Hi)} (32 × 32 × 32) M = {(Mi × Hi)} (32 × 32 × 32) Y = {(Yi × Hi)} (32 (× 32 × 32) Next, the second color conversion processing will be described in detail with reference to FIG.

In FIG. 4, reference numerals 6A and 6B denote density data of pixels stored in the memory 2;
A is a value after the color conversion processing for A, and 7B is a value after the color conversion for the density data 6B.

Here, the value 7A after the color conversion processing for the density data 6A is obtained by the above-described first color conversion processing, and the value 7B after the color conversion processing for the density data 6B is obtained.
Is obtained as the second color conversion processing, for example, as in (Equation 2).

(Equation 2) Cyan_b = Cyan_a-Red_a + Red_b Magenta_b = Magenta_a-Green_a + Green_b Yellow_b = Yellow_a-Blue_a + Blue_b where Red_a is the density data 6a and Red_a is the density data 6a.
Red_b is the red value of the density data 6b,
n_a is the green value of the density data 6a, Green
_B is the green value of the density data 6b, and Blue_a
Is the blue value of the density data 6a, and Blue_b is the blue value of the density data 6b. Cyan_a is the cyan value of the value 7a after the color conversion processing, Cyan_b is the cyan value of the value 7b after the color conversion processing, and Magenta
_A is the value of magenta after color conversion processing 7a, and
ta_b is the magenta value of the value 7b after the color conversion processing,
Yellow_a is the yellow value of the value 7a after the color conversion processing, and Yellow_b is the yellow value of the value 7b after the color conversion processing.

Next, a case where the number of pixels stored in the memory 2 is five and all the stored pixels are on the same line will be described.

First, when RGB image density data dr, dg, db is input to the density data input unit 1, the input density data of five pixels on the same line is stored in the memory 2.

Then, among the five density data stored in the memory 2, the above-described first color conversion processing is performed on the density data 6C of the first pixel and the density data 6G of the last pixel.

Next, of the five density data stored in the memory 2, the second color conversion processing is performed on the density data 6D, 6E, and 6F of the pixels for which the first color conversion processing has not been performed. Do.

Here, the second color conversion processing will be described with reference to FIG.
The details will be described with reference to FIG.

In FIG. 5, 6C, 6D, 6E, 6F,
6G is the density data of the pixel stored in the memory 2,
7C is a value of the density data 6C after the color conversion processing, 7D is a value of the density data 6D after the color conversion processing, 7E is a value of the density data 6E after the color conversion processing, and 7F is a density data 6F. 7G is a value after the color conversion for the density data 6G.

The value 7C after the color conversion processing for the density data 6C is obtained by the above-described first color conversion processing. Similarly, the value 7G after the color conversion processing for the density data 6G is also obtained by the first color conversion processing. And the density data 6
Values 7D, 7E, after color conversion processing for D, 6E, 6F
7F is obtained as the second color conversion processing, for example, as in (Equation 3).

(Equation 3) Cyan_e = ((Red_e-Red_g) × Cyan_c + (Red_c-Red_e) × Cyan_g) ÷ (Red_c−Red_g) ) {(Green_c-Green_g) Yellow_e = ((Blue_e-Blue_g) * Yellow_c + (Blue_c-Blue_e) * Yellow_g) {(Blue_c-Blue_g) where Red is the value of Red_c,
Red_e is the red value of the density data 6e,
g is the red value of the density data 6g, Green_c is the green value of the density data 6c, Green_e is the green value of the density data 6e, Green_g is the green value of the density data 6g, and Blue_c is the green value of the density data 6c. Blue_e is the density data 6e
And Blue_g is the blue value of the density data 6g. Also, Cyan_c is the cyan value of the value 7c after the color conversion process, Cyan_e is the cyan value of the value 7e after the color conversion process, Cyan_g is the cyan value of the value 7g after the color conversion process, and Magenta_c is the color. Magenta_e is the magenta value of the converted 7c, and Magenta_e is the magenta value of the value 7e after the color conversion.
Is a magenta value of 7 g after the color conversion processing,
w_c is a yellow value of the value 7c after the color conversion processing,
“low_e” is a yellow value having a value of 7e after the color conversion processing, and Yellow_g is a yellow value having a value of 7g after the color conversion processing.

Next, a case where the number of pixels stored in the memory 2 is five and the stored pixels are on three lines will be described.

First, when RGB image density data dr, dg, db are input to the density data input unit 1, the input density data of five pixels on three lines is stored in the memory 2.

Then, among the five density data 6H, 6I, 6J, 6K, and 6L stored in the memory 2, the above-described first color conversion processing is performed on the density data 6H, 6I, 6JK, and 6L. Do.

Next, of the five density data stored in the memory 2, the second color conversion processing is performed on the density data 6J of the pixels for which the first color conversion processing has not been performed.

Here, the second color conversion processing will be described with reference to FIG.
The details will be described with reference to FIG.

In FIG. 6, 6H, 6I, 6J, 6K,
6L is density data of a pixel stored in the memory 2;
7H is the value of the density data 6H after the color conversion processing, 7I is the value of the density data 6I after the color conversion processing, 7J is the value of the density data 6J after the color conversion processing, and 7K is the density data 6K. 7L is a value after the color conversion for the density data 6L.

The value 7H after the color conversion processing for the density data 6H is obtained by the above-described first color conversion processing, and the value 7I after the color conversion processing for the density data 6I is also obtained by the first color conversion processing. The value 7K after the color conversion processing for the density data 6K is also obtained by the first color conversion processing, the value 7L after the color conversion processing for the density data 6L is also obtained by the first color conversion processing, and the color for the density data 6J is obtained. The value 7J after the conversion processing is obtained as the second color conversion processing, for example, as shown in (Equation 4).

(Equation 4) Cyan_j = ((Red_h−Red_j) × Cyan_l + (Red_i−Red_j) × Cyan_k) + (Red_k−Red_j) × Cyan_i) + (Red_l−Red_j) × Cyan_h) − (− Red) | + | Red_i-Red_j | + | Red_k-Red_j | + | Red_l-Red_j |) Magenta_j = ((Green_h-Green_j) * Magenta_l + (Green_i-Green_j_Gen_Gen_Gen_k) (Green_l-Green_j) × Magenta_h) {(| Green_h-Green_j | + | Green_i-Green_j | + | Green _K-Green_j | + | Green_l-Green_j |) Yellow_j = ((Blue_h-Blue_j) * Yellow_l + (Blue_i-Blue_j) * Yellow_k) + (Blue_k_Blue_Blue_jl) | Blue_h-Blue_j | + | Blue_i-Blue_j | + | Blue_k-Blue_j | + | Blue_l-Blue_j |) where Red_h is the red value of the density data 6h,
Red_i is the red value of the density data 6i,
j is the red value of the density data 6j, Red_k is the red value of the density data 6k, and Red_l is the density data 6
1 is a red value, Green_h is a green value of the density data 6h, Green_i is a green value of the density data 6i, Green_j is a green value of the density data 6j, and Green_k is a green value of the density data 6k. , Green_l is the green value of the density data 6l, Blue_h is the blue value of the density data 6h, Blue_i is the blue value of the density data 6i, and B
blue_j is the blue value of the density data 6j,
_K is the blue value of the density data 6k, and Blue_l is the blue value of the density data 6l.

Cyan_h is a value 7 after the color conversion processing.
h is a cyan value, and Cyan_i is a value 7 after the color conversion processing.
i is a cyan value, and Cyan_j is a value 7 after color conversion processing
j is the cyan value, and Cyan_k is the value 7 after color conversion processing
k is a cyan value, and Cyan_l is a value 7 after color conversion processing
1 is a cyan value, Magenta_h is a magenta value of 7h after color conversion processing, Magenta_i is a magenta value of value 7i after color conversion processing, and Magenta_j is a magenta value of 7j after color conversion processing. Agent
a_k is a magenta value of a value 7k after the color conversion processing,
genta_l is the magenta value of the value 7l after the color conversion process, Yellow_h is the yellow value of the value 7h after the color conversion process, Yellow_i is the yellow value of the value 7i after the color conversion process, and Yellow_j is the color conversion process The later value 7j is the yellow value of the value 7j, Yellow_k is the yellow value of the value 7k after the color conversion process, and Yellow_l is the yellow value of the value 7l after the color conversion process.

As described above, according to the present embodiment, the values of a plurality of pixels are stored in the memory, color conversion is performed on a smaller number of pixels than the stored number of pixels, and The color conversion is performed on the pixels that have not been subjected to the color conversion using the values of the pixels that have been subjected to the color conversion and the values of a plurality of pixels stored in the memory, so that the color conversion processing is speeded up. It becomes possible.

Here, the color conversion processing device described above can be realized also by software.

That is, as shown in FIG.
1, display 12, hard disk 13, memory 1
4. Floppy (registered trademark) disk drive 15, M
O disk drive 16, CD-ROM drive 17,
A computer system including the scanner 18 is constructed, and the values before and after the color conversion processing of the target pixel and the surrounding pixels are stored on a recording medium such as a floppy disk, an MO, a CD-ROM, or the like, from which data can be read by the computer system. A program for realizing a function of obtaining the value of the pixel of interest after the color conversion processing from the value of the pixel after the color conversion processing is recorded.

When an image is input, it is temporarily stored on a hard disk or the like. Here, when the program is executed, the stored image data is read,
A color conversion process using the first color conversion process and the second color conversion process is performed, and the result is output to the display 12 or the like.

[0058]

As described above, according to the present invention, the values of a plurality of pixels are stored in a memory, color conversion is performed on a smaller number of pixels than the number of stored pixels, and Color conversion is performed for pixels that have not undergone color conversion using the values of the pixels that have undergone color conversion and the values of a plurality of pixels stored in the memory. An effective effect that it becomes possible to achieve this is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a color conversion processing device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a color conversion process in the color conversion processing device.

FIG. 3 is an explanatory diagram showing a reference lookup table used for color conversion processing in the color conversion processing device.

FIG. 4 is an explanatory diagram showing an example of a color conversion process in a second color conversion unit of the color conversion processing device of FIG.

FIG. 5 is an explanatory diagram illustrating another example of the color conversion processing in the second color conversion unit of the color conversion processing device in FIG. 1;

FIG. 6 is an explanatory diagram showing still another example of the color conversion processing in the second color conversion unit of the color conversion processing device in FIG. 1;

FIG. 7 is an explanatory diagram showing a specific development example of the color conversion processing device of FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 density data input section (input section) 2 memory 3 first color conversion section 4 second color conversion section 5 output section

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B057 AA11 CA01 CA16 CB01 CB16 CE11 CE18 CH07 CH11 CH12 DB06 5C077 LL18 MP08 PP15 PP32 PP33 PQ22 PQ23 5C079 HB01 HB02 HB03 LA21 LB12 MA01 MA04 NA11 PA02 PA03

Claims (3)

[Claims] An input unit to which data of a first image format is input; a memory in which values of a plurality of pixels input by the input unit are stored; and a number smaller than the number of pixels stored in the memory. A first color conversion unit that performs a color conversion process on the pixels of the second image format into data of a second image format; and a color conversion process is performed by the first color conversion unit among the pixels stored in the memory. A second color conversion process is performed on the missing pixels using the values of the plurality of pixels stored in the memory and the values color-converted by the first color conversion unit into data of a second image format. A color conversion processing device comprising: a color conversion unit; and an output unit that outputs a value that is color-converted by the first color conversion unit and the second color conversion unit. 2. The color conversion processing device according to claim 1, wherein the data stored in the memory is pixels on the same line or pixels on a plurality of lines. 3. A step of inputting data of a first image format, a step of storing input pixel values, and a second image format for a number of pixels smaller than the stored number of pixels. Performing a color conversion process on the stored data, and for a pixel that has not been subjected to the color conversion process among the stored pixels, a second process is performed using the stored values of the plurality of pixels and the already color-converted value. A program for executing a step of performing a color conversion process on data of the image format and a step of outputting a color-converted value.