JP2001189871A - Color image processing method and color inage processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain natural color adjustment in RGB space by properly deciding a correction area. SOLUTION: A color adjustment area is decided by using a relative luminance value of an adjustment object color with respect to a representative color and an adjustment quantity with respect to a color in the adjustment area is calculated. Then color adjustment processing is applied to the color within the adjustment area based on the calculated adjustment quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a color adjustment technique for a color image performed in an RGB space, and more particularly to an improvement in a method of determining a color correction (adjustment) area.

[0002]

2. Description of the Related Art In general, there are a YUV system represented by a television and an RGB system represented by a personal computer as a method of expressing colors in a color image. In the YUV method, the color of an image is specified by luminance (Y) and color component (UV). On the other hand, in the RGB system, R (red), G
The color is specified by the ratio of each component of (green) and B (blue).

When performing color adjustment (correction) of an image in an RGB space, it is general to designate one representative color, adjust the representative color, and then adjust colors near the representative color.

[0004]

In the RGB space,
The color is specified by the ratio of RGB, but the same color may have different luminance. For this reason, according to the conventional color adjustment method, even if the colors are the same, the brightness may be different, and thus the colors may be outside the correction area. As a result, colors that should be adjusted but are not adjusted occur, and natural color adjustment cannot be performed. Such a problem is conspicuous when a large number of the same colors having different luminances exist, such as a gradation image. On the other hand, when performing color adjustment in the YUV space, since the color difference (U, V) is adjusted, the above-described problem does not basically occur.

When color adjustment of a color image is performed in the RGB color space, one of the colors may be saturated (exceeding the expression limit), and as a result, the ratio of R, G, and B components changes, This may cause color misregistration. On the other hand, Y
Even when performing color adjustment processing of an image in the UV space, the color difference U,
Any of V may be saturated, causing color shift.

The present invention has been made in view of the above situation, and a color image processing method and a color image processing apparatus capable of performing natural color adjustment in an RGB space by performing appropriate color adjustment area determination. The purpose is to provide.

[0007]

In order to solve the above-mentioned problems, in a color image processing method according to a first aspect of the present invention, a color adjustment area is determined using a relative luminance value of an input pixel with respect to a representative color. Then, an adjustment amount for the input pixel is calculated. Then, when the input pixel is within the adjustment area, the color adjustment processing is performed on the input pixel based on the calculated adjustment amount. For example, by multiplying the RGB pixel value of the input pixel by the relative luminance value, the luminance of the input pixel is not affected in the area determination.

[0008] A color image processing apparatus according to a second aspect of the present invention includes a relative luminance calculation circuit for calculating a relative luminance value of an input pixel with respect to a representative color; And an adjustment area determination circuit for determining an adjustment area. The image processing apparatus further includes an adjustment processing circuit that calculates a color adjustment value of the input pixel and performs color adjustment of the input pixel based on the calculated adjustment value when the input pixel is within the adjustment area determination. For example, a multiplier for multiplying the RGB pixel value of the input pixel by the relative luminance value is provided. In the adjustment region determination circuit, the output of the multiplier is used so that the luminance of the input pixel does not affect the region determination.

In the present invention as described above, since the luminance component of the input pixel (color to be adjusted) does not affect the determination of the adjustment area, some colors having the same color (hue) but different luminances are adjusted. Without the inconvenience of going outside,
Natural color adjustment can be performed. That is, according to the present invention, by making an appropriate adjustment region determination, R
There is a special effect that natural color adjustment can be performed in the GB space.

[0010] In the present invention as described above, more preferably, when the adjustment value is added to each of the RGB color components, RGB values are used.
The saturation state of each color is detected, and the addition process is adjusted based on the detection result. This makes it possible to prevent color shift due to saturation of any color.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. In the embodiments described below, a method and apparatus for correcting one color (representative color) of an RGB digital image and colors in the vicinity thereof will be described as an example.

First, the basic principle of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining the concept of a color adjustment region determination method for a color image according to an embodiment of the present invention, and shows an RGB color space. FIG. 2 shows an equation applied to the calculation in the present embodiment.

In this embodiment, the luminance Y is obtained from the input signal (RGB signal) by the equation (1) in FIG. In Equation (1), r, g, and b are constants (r + g + b = 1),
For example, the ratio is set as follows. r = 0.299 g = 0.587 b = 0.114

In this embodiment, a predetermined correction (adjustment)
In order to correct all colors having the same hue existing in the region, R
The GB signal is normalized by luminance. The “same color” color means a color having a constant ratio of “RGB”. As can be seen from equation (1), the luminance is not constant even for the same hue. That is, there can be colors having the same hue and completely different luminances. In the present invention, even if the luminance is different, if the color is the same, it is ensured that the color enters the correction area.

Next, the luminance Y ₀ of the representative color (selected color) is calculated (designated) based on the equation (2). The Y _0, for instance, specify the point at which luminance is the center of the dynamic range. In the RGB space, the region to be corrected near the representative color has a range represented by Expression (3) when the region is a sphere. The range shown in equation (3) is, in FIG.
The k ₀ as the center, corresponding to the inside of the sphere of radius L _0.

[0016] When the internal region to be corrected is a sphere k _0, there is the color of different shades the same brightness is out of the area. Therefore, in this embodiment, the origin of the RGB space (0) and the vertex, the interior of the cone 10 the ball k ₀ is inscribed with the region to be corrected. When such a setting (judgment) method is expressed by an equation, the equation (4) is obtained. That is, the relative luminance “Y ₀ / Y” is added to the pixel value “P” of the input pixel (target pixel).
Multiply by This makes it possible to absorb the influence of luminance in the RGB space, and to correct all colors having different luminances and the same hue. _"Y 0 / _Y"
Indicates the relative luminance of the selected color with respect to the luminance of the input pixel.

When the operation represented by the equation (4) is realized by hardware, it is desirable to convert the operation to the equation (5).
That is, all divisions are converted into multiplications. _{"Y 0"}
Is a constant, the determination of the color correction target area can be realized only by the multiplier. In the example shown in FIG. 1, the correction target area is a cone in which the sphere k ₀ is inscribed. However, with the same idea, for example, a cone in which a regular octahedron is inscribed may be used, or the origin of the RGB space may be used. It is also possible to use a mathematical solid that can be expressed mathematically with the vertex as a vertex.

The pixel P that satisfies the condition of the equation (5) exists inside the sphere K having a radius L ₀ × Y / Y ₀ also having a center on a straight line connecting the center of the sphere k ₀ and the origin shown in FIG. I do. Therefore, the calculation of the color correction is as shown in Expression (6).

Finally, equations (6) and (7)
By performing the calculation shown in equation (8) based on
Elementary color adjustment (color correction) can be performed. Note that FIG.
The second term of the equation (8), Y / Y₀− (1 / L₀) × | P_in-C₀× (Y / Y
₀) |｝ × ΔC₀  Is equivalent to ΔP shown in the claims of the claims.
I do.

In the specification, "P" and "C" indicate vector values in the RGB color space. In the same sense, in FIGS. 2 to 7, “P” and “C” in italic font indicate vector values in the RGB color space.

Next, an image processing apparatus and an image processing method including the color adjustment determining apparatus for realizing the above-described color adjustment area determining method will be described with reference to the block diagram shown in FIG.
The color image processing device shown in FIG. 3 includes an image input device 12 for outputting input pixel data (P _in ), a correction area designating memory 14, color data C ₀ and luminance data 1 of a representative color (selected color). / Color memory 1 for designating representative color that holds ₀
6 and a correction amount designating memory 18 for holding the correction amount ΔC ₀ of the representative color. Correction area designation memory 14
Holds the maximum value L ₀ of the distance in the RGB space of the representative color and the input pixel (correction target color).

The color image processing apparatus according to the present embodiment further executes a relative luminance operation circuit 20 for executing the operation of Expression (1) shown in FIG. 2, a multiplier 24, and an operation of Expression (5). A color correction area determination circuit 26 that determines a color correction area by the above operation, and a correction calculation circuit 2 that performs a calculation shown in Expression (8)
8, a selector 30, and an image output device 32.

One of the two output terminals of the image input device 12 is connected to the input terminal of the selector 30 and the input terminal of the color correction area judging circuit 26, and the other is connected to the input terminal of the relative luminance calculation circuit 20. Then, RGB data _{P in} of the input pixel from the image input device 12 is supplied to the relative luminance calculation circuit 20, a selector 30 and the color correction region determining circuit 26.
The output terminal of the correction area designating memory 14 is
And the maximum value L of the distance in the RGB space between the representative color and the input pixel (correction target color).
₀ is supplied.

One of the output terminals of the representative color designation memory 16 is connected to the input terminal of the relative luminance calculation circuit 20, and the other output terminal is connected to the input terminal of the multiplier 24. The luminance data 1 / Y ₀ is supplied to the relative luminance calculation circuit 20, and the color data C of the representative color (selected color) is supplied to the multiplier 24.
₀ is supplied. Correction amount designation memory 1
The output terminal 8 is connected to the input terminal of the correction operation circuit 28, and supplies the correction amount ΔC ₀ of the representative color.

The output terminal of the relative luminance calculation circuit 20 is connected to the input terminal of the color correction area judging circuit 26, the input terminal of the multiplier 24, and the input terminal of the correction calculation circuit 28. Then, the color correction region determining circuit 26, a multiplier 24 and the correction operation circuit 28, and supplies the relative luminance value Y / Y _0.

The output terminal of the color correction area determination circuit 26 is connected to the input terminal of the correction operation circuit 28 and the input terminal (control terminal) of the selector 30. Color correction area determination circuit 2
6, as data for determining the distance Δr from the center of the input pixel P _in the sphere k for correction calculation circuit 28,
(1 / L ₀ ) × | P _in −C ₀ × (Y / Y ₀ ) | Further, a control signal indicating whether or not the input pixel is within the correction area is supplied to the selector 30.

The output terminal of the correction operation circuit 28 is connected to a selector
30 are connected to one input terminal. Correction calculation circuit
28 is a memory 18 for designating a correction amount, a relative luminance calculation circuit 2
0 and data ΔC supplied from the color correction area determination circuit 26₀, Y / Y₀, | P_in-C₀× (Y / Y₀) ｜ ×
1 / L₀  Y / Y as the correction value of the input pixel based on₀− | P_in-C₀× Y / Y₀| × 1 / L₀  Is calculated. The correction operation circuit 28 further calculates the equation (8)
Input pixel P according to_inThe pixel value RGB of
You.

The selector 30 includes a color correction area determination circuit 26
Supplied from the image input device 12 based on the control signal from
Color data P_inSupplied from the correction operation circuit 28
Color data P after correction_in+ ｛Y / Y₀− (1 / L₀) × | P_in-C₀×
Y / Y₀|｝ × ΔC₀  Either of P_outTo the image output device 32
I do. That is, the input pixel P_inIs within the correction area
Represents the corrected data supplied from the correction arithmetic circuit 28.
Select the input pixel P_inIf is outside the correction area,
Input data P supplied from the input device 12_inSelect
You.

The correction operation circuit 28 has the above-described functions.
In addition, it is preferable to add a saturation processing function. sand
That is, one of the colors is saturated at the stage of the RGB color correction.
Perform a process to prevent sloshing. First, FIGS. 4 and 5
The first method of the saturation processing will be described with reference to FIG. Less than
In the following description, in equation (8) above, ｛Y / Y₀− (1 / L₀) × | P_in-C₀× Y / Y₀
|｝ × ΔC₀  With the color correction component ΔP (= ΔR, ΔG, Δ
B).

In the first method, first, the color correction components ΔP (= ΔR, ΔG, ΔB) are equally divided into n (n> 1),
The value ΔP / n (= ΔR / n, ΔG / n, ΔB / n) is added to each color. If any of the colors is saturated at this stage, the value obtained by stopping the addition is output to the image output device 32 as an output P _out . When none of the colors is saturated, the value ΔP / n (= ΔR / n, ΔG /
n, ΔB / n) are added to each color. Such an operation is repeated at most n times, and when any color is saturated, the addition is stopped and the obtained value is used as a P _out signal (R _out , G _out) .
_out , B _out ) to the image output device 32.

In the actual arithmetic processing, the number of arithmetic operations is particularly small when n = 4 (the hardware configuration can be simplified). Therefore, in the preferred embodiment shown in FIGS. 4 and 5, n = 4. . In this case, since red (R) is saturated in the third addition, P + 3ΔP / 4 is used as the output signal P _out without performing the fourth addition.

The detection of the saturated state can be realized by a so-called overflow detection. That is, when performing the addition of 8 bits + 8 bits, “0” is added to the highest order in both the addition number and the augend, and the operation is performed with 9 bits. When the result of the addition exceeds the 8-bit range, "1" is entered at the ninth bit. Therefore, by detecting the ninth bit for R, G, and B, it can be determined whether the color is saturated.

The division of the color correction component ΔP is not limited to four, but by dividing it into four, the hardware configuration can be simplified (the number of operations can be reduced).

Next, a second method of the saturation processing in the correction operation circuit 28 will be described. In the second method, first, the color correction component ΔP (= ΔR, ΔG, ΔB) is set to n
(N> 1), and divide the value into ΔP / n (= ΔR / n, Δ
G / n, ΔB / n) are added to each color. If any color is saturated at this stage, the value ΔP / 2n (= ΔR
/ 2n, ΔG / 2n, ΔB / 2n) are subtracted from each color. And finally, P + ΔP / 2n (= R + Δ
R / 2n, G + ΔG / 2n, and B + ΔB / 2n are output to the image output device 32 (display device) as output signals P _out (R _out , G _out , B _out ).

On the other hand, the value ΔP / n (= ΔR / n, ΔG /
If none of the colors is saturated at the time when n, ΔB / n) are added to each color, the value ΔP / 2n (= ΔR / 2)
n, ΔG / 2n, ΔB / 2n) for each color.
The addition processing ends. That is, P + 3ΔP / 2n (=
R + 3ΔR / 2n, G + 3ΔG / 2n, B + 3ΔB / 2
n is the output signal P _out (R _out , G _out ,
B _out ) to the image output device 32.

In the embodiment shown in FIGS. 6 and 7, "2" is adopted as the number of divisions n in the second method. The main reason for setting n = 2 is to simplify the hardware configuration and reduce the number of operations as in the first method described above.

Also in the second method, the detection of the saturated state can be realized by the overflow detection described above.
According to the second method, since the saturation processing can be performed by two-stage addition (subtraction) processing, the hardware configuration can be further simplified as compared with the first method.

FIG. 8 is a diagram for explaining the concept of a method for determining a color adjustment region of a color image according to another embodiment of the present invention, and shows an RGB color space. In this embodiment, FIG.
In addition to the embodiment shown in FIG. 2, the determination of the color adjustment target area is further improved.

In the present embodiment shown in FIG. 1, the origin (0) of the RGB space is set as the vertex, and the cone 10 in which the sphere k ₀ is inscribed.
Is set as the correction target area. In the embodiment shown in FIG. 8, the inside of the cone 100 or 200 is set as the correction target area. In the color adjustment standardized by the luminance, the effect of the correction may be too conspicuous to human eyes at low luminance, that is, in a dark part, which may be unnatural. Therefore,
In the embodiment shown in FIG. 8, the correction is not performed on the color with low luminance (lower figure) or the correction amount is made smaller (upper figure). Since the present invention performs color adjustment using relative luminance, when the embodiment shown in FIG. 8 is specifically realized,
It is only necessary to make an improvement in the part where the relative luminance is required. In the embodiment shown in FIG. 1, the luminance value Y / Y ₀ is used, whereas in the embodiment shown in FIG. 8, Y ′ / Y _{0 is used.}
Is used. That is, a so-called mapping process is performed.

In the embodiment shown in FIG. 8, similarly to the embodiment shown in FIG. 1, when the luminance Y is defined by “Y = 2R + 4G + B”, the embodiment shown in FIG. This can be realized only by using a 12-bit output ROM that inputs bits. In this case, the circuit scale of the ROM is about ²⁵ × 5 × 12 = 2000 gates. When a rewritable lookup table is used,
The boundary of the correction target area in the RGB color space can be an arbitrary curve, that is, the color adjustment characteristics can be user-defined.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, but can be modified within the scope of the technical idea described in the claims. is there.

[0042]

As described above, according to the present invention, the color adjustment area is determined using the relative luminance value of the input pixel with respect to the representative color, and the adjustment amount for the color within the adjustment area is calculated. A color adjustment process is performed on the input pixels based on the adjustment amount. For this reason, the luminance component does not affect the determination of the adjustment area, and some colors having the same color (hue) but different luminances do not fall outside the adjustment area.
Natural color adjustment can be performed. That is, the present invention has a special effect that natural color adjustment can be performed in the RGB space by performing appropriate correction region determination.

When performing color correction of an input pixel, RG
By detecting the saturation state of each value B and adding a correction value according to the state, it is possible to prevent the occurrence of a color shift due to saturation during color adjustment.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a basic concept (color adjustment area) of the present invention.

FIG. 2 is a formula or the like showing a calculation method of a basic concept of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a color image adjustment device according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a first method in a color adjustment saturation process applied to the embodiment;

FIG. 5 is an explanatory diagram schematically showing the operation shown in FIG. 4;

FIG. 6 is a flowchart illustrating a second method in a color adjustment saturation process.

FIG. 7 is an explanatory diagram schematically showing the operation shown in FIG. 6;

FIG. 8 is an explanatory diagram showing a basic concept (color adjustment area) of another embodiment of the present invention.

[Explanation of symbols]

10, 100, 200 Color adjustment area (cone etc.) of the present invention 12 Image input device 14 Memory for specifying correction area 16 Memory for specifying representative color 18 Memory for specifying correction amount 20 Relative luminance operation circuit 22, 24 Multiplier 26 Color Correction area judgment circuit 28 Correction operation circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H04N 9/64 H04N 1/46 Z F-term (Reference) 5B057 BA25 CA01 CA08 CA12 CA16 CB01 CB08 CB12 CB16 CC01 CE17 CE18 CH08 CH11 CH18 DA08 DA17 DB02 DB06 DB09 DC03 DC36 5C066 AA03 AA13 CA08 CA11 DD06 EA03 EB01 EE04 EF03 GA01 GA05 GA11 GA32 GA33 GB01 HA02 JA01 KA12 KD02 KE02 KE07 KE11 KE16 5C077 LL01 LL19 PP32 P00P12 PP19 LA24 LA31 LB01 MA01 MA02 MA11 NA05 5C082 AA01 AA02 BA12 BA34 BB02 CA12 CA54 MM10

Claims (18)

[Claims] 1. A representative color of a color image and its surrounding colors are represented by R
In a color image processing method for adjusting in a GB color space, for an input pixel, a region to be adjusted is determined using a relative luminance value with respect to the representative color, and an adjustment amount for the input pixel is calculated. A color image processing method comprising: performing a color adjustment process on the input pixel based on the adjustment amount when it is determined that the input pixel is within the area. 2. The method according to claim 1, wherein, when the area is determined, the relative luminance value is multiplied by an RGB value of the input pixel so that the luminance of the input pixel is not affected. The color image processing method described in the above. 3. The luminance Y of the input pixel is obtained by the following equation (1): Y = rR + gG + bB (1) (where r, g, and b are constants, and the total is a constant. The luminance Y _{0 of the} representative color is obtained by the following equation (2): Y = rR ₀ + gG ₀ + bB ₀ (2) (r, g, and b are constants) , The sum is a standardized value that is a certain constant.) The RGB pixel value of the input pixel is P, and the RGB value of the representative color is R.
When the GB pixel value is C ₀ and the maximum value of the distance between P and C ₀ in the RGB space is L ₀ , when the following expression (3) is satisfied, it is determined that the input pixel is within the area. 3. The color image processing method according to claim 2, wherein: | P × (Y ₀ / Y) −C ₀ | ² ≦ L ₀ ² (3) 4. The formula (3) is converted into the following formula (4):
4. The color image processing method according to claim 3, wherein the adjustment area is determined based on the equation (4). ｛(1 / L ₀ ) × | P−C ₀ × (Y / Y ₀ ) |｝ ² ≦ (Y / Y ₀ ) ² (4) 5. A method according to claim 1, wherein a predetermined range of low brightness in said area is narrowed as compared with another range, or color adjustment is not performed within said range. 5. The color image processing method according to 3 or 4. 6. The color adjustment processing includes a step of adding the adjustment amount to each of RGB color components, and a step of detecting a saturation state of each of the RGB colors and adjusting the addition processing based on the detection result. The color image processing method according to claim 1, 2, 3, 4, or 5. 7. The method according to claim 1, wherein in the step of adding the adjustment amount to each of the RGB components, the adjustment amount is divided, and the divided adjustment amounts are added stepwise to the RGB components in the adjustment region. 7. The color image processing method according to 6. 8. When the adjustment amount is ΔP, the adjustment amount ΔP is divided into n equal to ΔP / n (n> 1), and ΔP / n is calculated for each color until one of the RGB colors is saturated. 8. The color image processing method according to claim 7, wherein the addition is performed. 9. When the adjustment amount is ΔP, the RGB values
First, ΔP / n (n> 1) is added to each of the colors. If any of the RGB colors is saturated by the addition of ΔP / n, ΔP / 2n is subtracted from each of the RGB colors. When none of the RGB colors is saturated by the addition of ΔP / n, ΔP / 2n is further added to each of the RGB colors.
8. The process of claim 7, further comprising the step of:
3. The color image processing method according to item 1. 10. A color image processing apparatus for adjusting a representative color of a color image and its surrounding colors in an RGB color space, a relative luminance calculation circuit for calculating a relative luminance value of an input pixel with respect to the representative color; An adjustment area determination circuit that determines an area for performing the adjustment based on the relative luminance value obtained by the arithmetic circuit; an adjustment amount for the input pixel is calculated; and an adjustment amount of the input pixel pixel is calculated based on the adjustment value. A color image processing apparatus comprising: an adjustment processing circuit for performing color adjustment. 11. The method according to claim 11, wherein the relative luminance value is calculated by using RGB of the input pixel.
The apparatus according to claim 1, further comprising a multiplier for multiplying a pixel value, wherein the adjustment area determination circuit uses the output of the multiplier so that the brightness of the input pixel does not affect the area determination. A color image processing apparatus according to claim 10. 12. An image input circuit for detecting an RGB pixel value P of the input pixel and calculating a luminance Y of the input pixel based on the following equation (1): Y = rR + gG + bB (1) ) (r, g, b are constants. a normalized value becomes the sum is constant) and RGB pixel value C ₀ of the representative color, the represented by the following formula (2) a memory for representative color designation for holding the luminance _{Y 0} of the representative _{colors; Y = rR 0 + gG 0} + bB 0 ···· (2) (r, g, b are constants, and the sum is constant the normalized value.) the representative color and further comprising a memory for modification region specified to hold the maximum value L ₀ of the distance in the RGB space of the input pixel, the adjustment region determining circuit, the image input circuit The representative color designation memory and the correction area designation memory The color image processing apparatus according to claim 11, wherein a color satisfying the following expression (3) is determined as an adjustment target based on the data. | P × (Y ₀ / Y) −C ₀ | ² ≦ L ₀ ² (3) 13. The adjustment area determination circuit according to the above equation (3).
13. The color image processing apparatus according to claim 12, wherein an operation represented by the following equation (4), which is obtained by transforming, is performed, and a color satisfying the equation (4) is determined as an adjustment target. ｛(1 / L ₀ ) × | P−C ₀ × (Y / Y ₀ ) |｝ ² ≦ (Y / Y ₀ ) ² (4) 14. The apparatus according to claim 10, wherein a predetermined range in which the brightness is low in said area is narrowed as compared with another range, or color adjustment is not performed within said range.
14. The color image processing apparatus according to 1, 12, or 13. 15. The adjustment processing circuit according to claim 1, wherein the adjustment value is RG
15. The method according to claim 10, wherein, when adding to each of the B color components, a saturation state of each of the RGB colors is detected, and the addition process is adjusted based on the detection result. Color image processing device. 16. The adjustment processing circuit divides the adjustment value, and divides the adjusted adjustment value into RGs in the color adjustment area in a stepwise manner.
12. The method according to claim 10, wherein the component is added to the B component.
16. The color image processing apparatus according to 12, 13, 14, or 15. 17. The adjustment processing circuit according to claim 17, wherein the adjustment value is ΔP
, The adjustment value ΔP is divided into n equal to ΔP / n (n
> 1), ΔP / n until one of the RGB colors is saturated
17. The color image processing apparatus according to claim 16, wherein is added for each color. 18. The adjustment processing circuit according to claim 18, wherein the adjustment value is ΔP
, First, ΔP /
n (n>1); by adding the ΔP / n,
If any of the RGB colors is saturated, ΔP / 2n is subtracted from each of the RGB colors; if none of the RGB colors is saturated by the addition of ΔP / n, RGB is added.
17. The color image processing apparatus according to claim 16, wherein ΔP / 2n is further added to each color.