JPS62149261A - Method and apparatus for adjusting color - Google Patents

Abstract

PURPOSE:To attain desired color adjustment simply without skill by using three color (red, blue, green) color adjusting coefficients so as to calculate the color adjusting quantity and adding the said color adjusting quantity to an output density before color adjustment. CONSTITUTION:After a color separation signal of an original picture is subject to a pre-processing such as shading correction and conversion to an END densi ty, the result is fed to a basic matrix masking circuit 1 and a discrimination output circuit 2 as input density signals B, G, R. The circuit 1 calculates output densities Y0, M0, C0 before color adjustment and the circuit 2 calculates a color discrimination output. Color discrimination outputs DB, DG, DR are outputted to a color adjusting masking circuit 4, where color correction coefficients alphaB, alphaG, alphaR outputted from the color adjustment coefficient circuit 3 are multiplied and each of color adjusting quantities DELTAY, DELTAM and DELTAC is outputted. Each of the color adjusting quantities DELTAY, DELTAM, DELTAC is added respectively to each of the densities Y0, M0 and C0 by an adder circuit 5 and the densities Y, M, C subject to color adjustment and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a color adjustment method and apparatus that reduce the number of color adjustments and eliminate the need for skill in color adjustment.

[Conventional technology]

As a conventional color adjustment device, for example, it can perform basic masking to remove incorrect absorption of ink color, and also perform masking to correct characteristic colors according to color distortion of the original image or the viewer's preference. I have a color scanner.

In the former masking, two signals are used: the signal that passes through the R (red), G (green), and B (blue) filters (white color) and the signal that is absorbed (black color). Y (yellow) 1M (magenta)
, C (cyan). Also,
For the latter masking, Y.

Y, M for six hues of M, C, B, G, and R.

Color adjustment is performed using each of C and K (black).

[Problem that the invention seeks to solve]

However, with conventional color adjustment devices, when adjusting colors,
The number of adjustments is large (6 to 32), and the number of color separations (
This has to be done for each color (Y, M, C, K), which is disadvantageous in that considerable skill is required in order to perform the color adjustment intended by the viewer.

Regarding this type of color adjustment device,
There are No. 0-14845 and JP-A-58-181045.

[Means and effects for solving the problems] The present invention has been made in view of the above, and in order to reduce the number of color adjustment devices and make color adjustment possible without requiring skill.
The present invention provides a color adjustment device and apparatus that add a color adjustment amount determined based on a color adjustment coefficient to an output density before color adjustment.

〔Example〕

Hereinafter, the color adjustment device and device according to the present invention will be explained in detail.

First, the principle of the present invention will be explained by showing mathematical formulas.

Output density Y o, M o, C before color adjustment
Matrix masking by o is expressed by the following equation.

However, B, G, and R are input concentrations, all to a'J3 are color correction coefficients.

In addition, the amount of change in Y, M, and C due to the color adjustment of the present invention is ΔY
, ΔM, and ΔC, the following equation is obtained.

However, α8. α. , α3 are color adjustment coefficients for blue, green, and red, respectively, Q'I+' = m! IC! @, αR' ”mQcXG
, αI! '=ml+11'.

(Each of m, , mc, and m is a constant).

From equations (1) and (2), Y, M, and C after color adjustment can be expressed by the following equations.

(D s ” = 2 B + G 1R, D
c = B 2 G + R.

D,=B+C,-2R.

Here, it is defined as follows.

These three conditions mean that the color of the original is judged.
That is, Dg is the blue area and DG is the edge area.

Dll means to judge the red area.

From this, it can be seen that the color adjustment of the present invention can be obtained by performing equation (4) under the conditions of equation (5).

Furthermore, the following equation is derived from equations (1) and (3).

The color adjustment of the present invention is realized by satisfying this equation (6).

Next, in order to hold the original grain, (11 type B
, G, R are input concentrations as END (equivalent neutral) concentrations,
The coefficient all'''a13 may satisfy the condition of the following expression.

By satisfying the condition shown in equation (7), (
2) Since the sum of the coefficients of the columns of the 3×3 matrix in the equation is set to 0, gray is always maintained.

As the matrix size for basic matrix masking, (3 rows and 3 columns was used in Equation 11, but in the color adjustment of the present invention, any matrix size can be used. For example, the following 3 rows and 9 columns is used. A column may also be used.

In this case, color adjustment may be performed for 3 rows and 3 columns in a matrix of 3 rows and 9 columns. Furthermore, in order to maintain gray, the input densities of B, G, and R may be set to END (equivalent neutral) densities, and the color correction coefficients all to a19 may be determined to satisfy the following equation.

By the way, equation (3) can be further expanded as shown in the following equation.

However, l1ff++β31 [G1. l Gl l
R1,/R2 are constants.

Therefore, DB = (131+1zr) B + 1zI
G + 13□RDc = lc, rB (Rat
+lr,□)G+J,2RD*=j2i+B+l*z
G (1*++1°)R.

In addition, in formula 001, 13r=exz=lal=lcz=1**=Il*t=
Equation (3) corresponds to when it is set to 1.

Red, green by choosing constants in the 0ψ equation.

It can be shifted from the blue color adjustment area.

Range that can be adjusted by color adjustment of the present invention (color adjustment area)
, the amount of strong color adjustment change) was shown numerically.
It is a table. The input density value is a value converted into a value from 0 to 255. The amount of change in color adjustment in Table 1 is shown in graphs in FIG. 7 (red color adjustment), FIG. 8 (green color adjustment), and FIG. 9 (blue color adjustment). Also, the amount of change (ΔY, ΔM
.

FIG. 10 shows the change in ΔC). (In addition, the 7th
The cases shown in Figures to Figure 10 are m, =mc =m=
= 0.5, and the values of αB, αG, and αR can be converted by changing the values of mH, mG, and mR.) When performing color adjustment, for example, if you want to emphasize red case,
As is clear from Figure 7, by increasing the red color correction coefficient αR, Y and M necessary for red reproduction are increased without changing the gray, and at the same time, unnecessary C is reduced for red reproduction. becomes possible. Note that the amount of color adjustment change is greatest for red in the original, Y and M are % of R, and G, B
, C do not change at all (see Table 1). The same holds true when green and blue are strengthened.

FIG. 1 shows an embodiment of the present invention, in which the matrix calculation shown in equation (8) is executed, and the output density Y o before color adjustment,
A basic matrix masking circuit 1 that outputs M o, Co, and an original color judgment output D8°Dc in equation (4).
, D++, and the color adjustment coefficient α.
8. α6. α1. Masking circuit 4 for color adjustment
By multiplying each output signal of the color adjustment coefficient circuit 3 and the judgment output circuit 2 by the color adjustment coefficient output from the color adjustment coefficient circuit 3, the color adjustment amounts ΔY, ΔM shown in equation (3) are obtained. ,
The color adjustment masking circuit 4 that calculates ΔC and the output density Y output from the basic matrix masking circuit 1.
Consisting of an adding circuit 5 that adds color adjustment amounts ΔY, ΔM, and ΔC output from a color adjustment masking circuit 5 to each of M, , C, and outputs output density signals Y, M, and C. be done. Note that the controller 6 includes a color adjustment coefficient circuit 3.
It has a function to set coefficients.

In the above configuration, the color separation signals of the original image are subjected to necessary preprocessing such as shading correction and conversion to END density, and then are input to the basic matrix masking circuit 1 and the judgment output circuit 2 as input density signals B, G, and R. is applied to The basic matrix masking circuit 1 calculates the output densities Yo, Mo, Co before color adjustment shown in equation (8),
The determination output circuit 2 calculates a color determination output based on equation (4). Color judgment output DB.

DG and DR are output to the color adjustment masking circuit 4, and in the circuit 4, the color correction coefficients α8. Each of αG and α is multiplied to output each of color adjustment amounts ΔY, ΔM, and ΔC based on equation (3).

Each of the color adjustment amounts ΔY, ΔM, and ΔC corresponds to the output densities Yo, Mo, and C output from the basic matrix masking circuit 1 by the addition circuit 5.

, and color adjustment is performed from the adding circuit 5.
, M, and C are output.

Figure 2 shows the details of the basic matrix masking circuit l, which is composed of ROM, allB+a,,B''
= a,,R+a,,R"J%')-r
- A multiplier 1 that multiplies pulls 101 to 109 and each of B, G, and R by a signal of one other color to obtain BG, BR, and GR.
10 to 112, memory tables 113 to 121 for determining a, 48 G''-a 36RB based on the output signals of the multipliers 110 to 112, and a memory table 101.
adders 122 to 124 that add two of the output signals of the adders 122 to 106, and adders 125 to 125 that add each output signal of the adders 122 to 124 and each output signal of the memory tables 107 to 109. 127, and the adder 125~
127 respective output signals and memory tables 113 to 11
adders 128 to 130 for adding the output signals of each of
and two of the output signals of memory tables 116 to 121.
Adders 131 to 133 that add two signals, and adder 1
adders 134 to 1 that add two signals from 28 to 133 and output output density signals Yo, Mo, and Co;
It is composed of 36 pieces.

In the configuration of FIG. 2, memory tables 101 to 109
by a++B+a+wB” ~a,,R+a,R”
is calculated, and a is determined by memory tables 113 to 121.
A matrix calculation value of each term of 148 G-a 36 RB is obtained, and each of the obtained terms is added to adders 122 to 122 for each color.
136 and the calculation of equation (8) is executed,
Each of Y o, M o, and Co is determined.

FIG. 3 shows the details of the judgment output circuit 2, including an adder 201 that adds the human force concentration signal G and R, and the human force concentration signal B (
! : an adder 202 that adds R; an adder 203 that adds input agricultural signals B and G; and a subtracter 204 that subtracts 2B from the output signal of the adder 201 to calculate (G+R-2B). , Similarly, (B+R-2G) and (B+G-
2R) and subtracters 205 and 206 that calculate
It is comprised of buffers 207-209 that selectively output the respective output signals of 04-206 using a carry signal, and pull-down resistors 210-212 connected between each output terminal of the buffers 207-209 and ground.

In the configuration shown in FIG. 3, the combination of adder 201 and subtracter 204 makes it necessary for the calculation of equation (3).

=-28+G+R is calculated, and adder 202 and subtracter 2
By the combination of 05, Da = 8 2G + R is calculated, and further by the combination of the adder 203 and the subtracter 206, DR = B + G = -2R is calculated. Each judgment output is output to buffers 207 to 209, but by inputting the sign bit to the output control terminal 100, when the result of subtraction is negative, the output of buffer 207 (or 208, 209) is suppressed, and the pull-down The output becomes O due to the effect of the resistor 704. Also, if the result of subtraction is positive, DB
(or DG, DR) is output.

FIG. 4 shows details of the color adjustment coefficient circuit 3, in which when an H level signal is applied as data to the D terminal, the selection signal αl SEL from the controller 6 is applied.

The H level signal based on α, SEL, αR3EL is given as α3. α6. It is composed of launches 301 to 303 that are output as α8. In such a configuration, for example, when α and SEL are output from the controller 6, an H level signal is output to the Q terminal of the latch 301 on the condition that an H level signal is given to the D terminal, and this It becomes αB. Launches 302 and 303 operate in the same manner, and each α6. Output α3.

FIG. 5 shows details of the color adjustment masking circuit 4, and shows the determination output signal D! Color adjustment coefficient α for each of l, DG, and DR
3. α6. Multiplying number items 401 to 40 for multiplying each of α1
3, and memory tables 404 to 4 that output values obtained by multiplying the multiplication results of the multipliers 401 to 403 by a constant m, respectively.
06, 407 to 409 that add two signals among the signals output from the multipliers 401 to 403, and the adder 4
Each output signal of 07 to 409 and memory table 404
~ 406 output signals are subtracted to obtain the color adjustment amount Δ
Subtractors 410 to 412 that output each of Y, ΔM, and ΔC
It consists of

In the configuration of FIG. 5, multipliers 401-403 each have α8D8. αG D G and αRD R are output,
Each of these multiplication outputs is multiplied by m by the memory tables 404 to 406, and from each of the memory tables 404 to 406, CtB' DB =rrzr,, Da,, e
tc,' Dc =m LxcDc, CX*' D
R=m αRDR is output to each of subtractors 410-412. On the other hand, adders 407 to 409 add αc[
) c+αRDR, αRD R+α! IDBI lαBD
Each of B+αGDG is added and output. These addition results are subtracted from the output values of memory tables 407 to 409 by subtracters 410 to 412, respectively, and ΔY−−αR′DB+αc[)c+αRDR.

ΔM=αBDB−α. 'DG + αRDR.

Each of ΔC=αBDB+αc, I)c−α, and l+DR is output from the subtractors 410 to 412.

In addition, αB, αG, α8. Since each α of αBZ G'+ α8'' is usually a value of about -1.0 to +1.0, in reality α8 to α8° are multiplied to an appropriate power of 2 to make an integer, and this is Digit alignment is performed by inputting the data into latches 301 to 303 shown in the figure and discarding the lower bits of the outputs of multipliers 401 to 403.

FIG. 6 shows the details of the addition circuit 5, and shows the output density Y o of the basic matrix masking circuit 1 before color adjustment.
, Mo, and Co, the color adjustment amounts ΔY, ΔM, and ΔC output from the color adjustment masking circuit 4 are added to each of them to obtain output density signals Y, M.

It is composed of adders 501 to 503 that output each of C. With this configuration, from each of the adders 501 to 503, Y ”” Y o +ΔY, M=Mo +6
M.

A color-adjusted output density signal of C=C, +ΔC is output.

Note that the basic matrix masking circuit 1 can include a color adjustment masking circuit 4. For example, each memory table 101 to 109 and 113 to 12 shown in FIG.
1, using rewritable memory (RAM),
The sign bit outputs of the subtracters 204 to 206 in FIG. 3 are added to the address line, and each color (B, G, R) is stored in this RAM.
This can be achieved by writing a total of 8 types of calculation tables, including those that perform color adjustment and those that do not.

〔Effect of the invention〕

As explained above, according to the color adjustment method and apparatus of the present invention, the color adjustment amount is calculated using the color adjustment coefficients for the three colors red, blue, and green, and the color adjustment amount is calculated as the output density before color adjustment. Since the color adjustment is added to the color separation image, color adjustment can be performed within a limited range with three adjustments, and there is no need to make adjustments for each color separation image.
Desired color adjustments can be easily made without requiring any skill.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing details of the basic matrix masking circuit 1 shown in FIG. 1, and FIG. 3 is a judgment output circuit 2 shown in FIG. 1.
4 is a circuit diagram showing details of the color adjustment coefficient circuit 3 shown in FIG. 1, FIG. 5 is a circuit diagram showing details of the color adjustment masking circuit 4 shown in FIG. 1, FIG. 6 is a circuit diagram showing details of the addition circuit 5 shown in FIG. 1, FIGS. 7, 8, and 9 are color adjustment amount change characteristic diagrams for each of red, green, and blue, and FIG. 10 4-≠←→ is a color adjustment amount change characteristic diagram when the red color adjustment coefficient is increased. Explanation of symbols 1-----1 matrix masking circuit, 2--
Judgment output circuit, 3---m-.-Color adjustment coefficient circuit, 4
---Masking circuit for color adjustment, 5-----1 addition circuit, 101-109. , 201 to 203 --- one addition circuit, 204 to 206 --- ifi calculation circuit, 207
~209--------Han 7y, 301~303~
--------Ly f, 401 to 403---Multiplier, 404 to 406---Memory table,
407 to 409. 501 to 503 --- Adder, 410 to 412 --- Subtractor. Patent applicant Fuji Xerox Co., Ltd. Agent Patent attorney Shin Matsubara 2 Seiji Muraki Jun Ueshima - Hiroaki Sakai Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (5)

[Claims] (1) Perform matrix masking by changing the color correction coefficients for the color separation signals B, G, and R of the original image,
In a color adjustment method that performs color adjustment, a color adjustment amount is calculated based on the color information of the original image and a preset color adjustment coefficient, and the output density before color adjustment obtained by the matrix masking is adjusted based on the calculation result. A color adjustment method characterized by: (2) The color adjustment method according to claim 1, wherein the sum of the matrix rows of the color adjustment coefficients is set to zero. (3) A patent characterized in that the absolute value of the sum of the color adjustment coefficients corresponding to the color separation signal to be color corrected is equal to the sum of the color adjustment coefficients corresponding to other color separation signals, and the signs are opposite to each other. A color adjustment method according to claim 1. (4) Constant l_B_ for the color separation signals B, G, and R.
1, l_B_2, l_G_1, l_G_2, l_R_1
, l_R_2 is added and subtracted to determine the color of the original image, D_B=-(l_B_1+l_B_2)B+l_B_1
G+l_B_2RD_G=l_G_1B-(l_G_1
+l_G_2)G+l_G_2RD_R=l_R_1B
In each of +l_R_2G−(l_R_1+l_R_2)R, when D_B<0, D_B=0 or the blue color adjustment coefficient is set to zero, when D_G<0, D_G=0 or the green color adjustment coefficient is set to zero, and D_R< D_R when 0
2. The color adjustment method according to claim 1, wherein the color adjustment coefficient of red is set to zero or zero. (5) a basic matrix masking circuit that performs matrix masking on the color separation signals of the original image; a determination output circuit that performs addition/subtraction processing on each of the color separation signals to determine the color of the original image; and an output signal of the determination output circuit. and a color adjustment masking circuit that outputs a color adjustment amount signal for modifying the output signal of the matrix masking circuit based on a color adjustment coefficient set for each color.