JP3784726B2 - Color adjustment device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color adjustment apparatus that performs color adjustment on a color image.
[0002]
[Prior art]
In a display device such as a monitor, when an input color signal is displayed, a color adjustment process is performed in order to output an image having a desired color reproducibility in accordance with a use condition or the like.
[0003]
In particular, the color signal is represented by three attributes of hue H, saturation S, and brightness V, and adjustment is performed. Since the HSV color space conversion process can handle hue, saturation, and brightness independently, saturation adjustment and brightness adjustment. Widely used.
[0004]
This is because the color space of the input color signal is converted into a color space represented by hue H, saturation S, and brightness V, adjusted in the HSV space, and then converted back to the original color space. Realized.
[0005]
When adjusting, a general method for uniformly adjusting each of hue, saturation, and lightness has an excessive or insufficient adjustment in the image data, which may result in an undesirable image. . For example, in the process of increasing the brightness, there is a problem that black becomes gray, the image is generally whitish, and the contrast is reduced.
[0006]
As a means for avoiding this, Japanese Patent Laid-Open No. 7-203231 discloses functions f (H) and f that can select color components of hue H, saturation S, and lightness L, respectively, although they are expressed in the HSL color space. A color image processing apparatus that flexibly converts input / output characteristics of hue, saturation, and lightness by converting according to (S) and f (L) is shown.
[0007]
FIG. 8 is a conceptual configuration block diagram in the embodiment of the above-mentioned publication. In FIG. 8, reference numeral 40 denotes a coordinate transformation that converts R, G, and B, which are input signals, into an HSL color space of hue, saturation, and brightness and outputs them. The circuit 42 is a selection circuit for selecting the output of the coordinate conversion circuit 40 or the HSL color space data on the CPU address bus 44, and 46 is a function f (H), f for the color components of hue H, saturation S, and lightness L, respectively. (S), a function conversion circuit for converting in accordance with f (L), 48 is a selection circuit for selecting the output of the function conversion circuit 46 or data on the CPU data bus 50, and 52 is an HSL color space output from the selection circuit 48. This is a coordinate reverse conversion circuit that returns color components to the RGB color space.
[0008]
Specifically, the functions f (H), f (S), and f (L) are set as appropriate, and the output f (H) of the input H, the output f (S) of the input S, and the output f ( L) solves the problem.
[0009]
Japanese Patent Laid-Open No. 2000-316095 discloses an image processing apparatus that creates a histogram of hue, saturation, and brightness, and adjusts hue, saturation, and brightness so that the histogram shape is appropriately converted. Yes.
[0010]
FIG. 9 is a conceptual configuration block unit in the embodiment of the above publication, in which 101 is a profile of input color image data, 102 is a color system conversion unit that converts input RGB data into an HSL color system, Reference numeral 103 denotes a pixel-of-interest setting unit that sequentially sets pixels of image data as a pixel of interest, 104 denotes a histogram creation unit that creates a one-dimensional histogram with hue, saturation, and brightness as horizontal axes, and 105 designates an achromatic color range. An achromatic color range designation unit 106 is a highest histogram search unit that retrieves the most frequent value from histograms obtained by removing the output range of the achromatic color range designation unit 105 from the output of the histogram creation unit 104, and 107 is an output of the target pixel setting unit 103 And a distance calculation reference designating unit for designating a distance calculation reference position used for color conversion from the output of the highest histogram search unit 106. Is a color conversion function designating unit for designating a function used for color conversion, and 109 is a color conversion function designated by the color conversion function designating unit 108 as an output of the target pixel setting unit 103 using an output of the distance calculation reference designating unit 107. A color conversion unit for multiplication, 110 is a general control unit that stores a signal indicating the end of processing of the target pixel to the target pixel setting unit 103 and stores the converted color data, and 111 is a table for converting from the HSL color system to the original RGB space. Inverse color system transformation.
[0011]
Specifically, instead of increasing the saturation and lightness of the entire image data, the dynamic range is expanded by converting the densely distributed color values around the histogram, thereby increasing the peak of the histogram. The contrast can be improved by lowering slightly.
[0012]
[Problems to be solved by the invention]
By the way, in order to perform flexible color adjustment such as retouching, not only the hue, saturation, and brightness are adjusted independently, but also saturation and brightness are adjusted for each hue, and saturation is adjusted by changing the brightness. Such complicated adjustment is necessary.
[0013]
For example, the natural harmony in color scheme theory is to make the color close to yellow bright and darken the color close to bluish purple, and to achieve a natural color scheme without any sense of incongruity. It is necessary to increase the lightness and lower the lightness of the bluish purple color, that is, to adjust the lightness by hue.
[0014]
Further, even in the adjustment of a tone that expresses a color with the degree of saturation and lightness, it is difficult to adjust the saturation and lightness independently, and the lightness by saturation and the saturation adjustment by lightness are necessary. FIG. 2 is a basic conceptual diagram of tones, where the vertical axis represents lightness and the horizontal axis represents saturation, and v (vivid: frightened), b (bright: bright), s (strong: strong), dp ( Deep: deep, lt (light: shallow), sf (soft: soft), d (dull: dull), dk (dark: dark), p (pale: thin), ltg (light grayish: light ash) , G (grayish: gray), dkg (dark grayish: dark gray), W (white: white), ltGy (light gray: light gray), Gy (gray: gray), dkGy (dark gray: dark) Gray) and Bk (black: black).
[0015]
On the other hand, the color adjustment disclosed in Japanese Patent Laid-Open No. 7-203231 can convert the output characteristics for each of the hue, saturation, and lightness inputs, but the input of one attribute affects the output of other attributes. Therefore, it is not possible to perform natural harmony that requires lightness adjustment by hue or tone adjustment that requires combined adjustment of saturation and lightness.
[0016]
Also, the color adjustment disclosed in Japanese Patent Laid-Open No. 2000-316095 is a process of transforming the histograms of hue, saturation, and lightness, and is the same as the previous publication in that the characteristics of output with respect to input are converted. Accordingly, there is a similar problem because an input of a certain attribute cannot affect an output of another attribute.
[0017]
The present invention has been made to solve the above problems, and its purpose is to adjust the other outputs according to the input of hue, saturation, and lightness, so that natural harmony and tone can be adjusted. An object of the present invention is to provide a color adjustment apparatus capable of performing flexible color adjustment such as adjustment.
[0018]
[Means for Solving the Problems]
In order to achieve the above-described object, the color adjustment apparatus according to the present invention is
Color space conversion means for converting the color signal as input data into hue Hi, saturation Si, and brightness Vi;
A hue adjustment value calculating unit that outputs the hue adjustment value Hh, the saturation adjustment value Hs, and the lightness adjustment value Hv by using the hue Hi output from the color space conversion unit;
A saturation adjustment value calculation unit that outputs the hue adjustment value Sh, the saturation adjustment value Ss, and the lightness adjustment value Sv by using the saturation Si output from the color space conversion unit;
A lightness adjustment value calculating means for outputting a hue adjustment value Vh, a saturation adjustment value Vs, and a lightness adjustment value Vv by using the lightness Vi output from the color space conversion means;
Hue adjustment means for adjusting the hue Hi of the input data using the hue adjustment values Hh, Sh, Vh output from the respective adjustment value calculation means;
Saturation adjustment means for adjusting the saturation Si of the input data using the saturation adjustment values Hs, Ss, Vs output from each of the adjustment value calculation means;
Brightness adjustment means for adjusting the brightness Vi of the input data using the brightness adjustment values Hv, Sv, Vv output from the respective adjustment value calculation means;
Color space inverse conversion means for converting the adjusted hue Ho, saturation So, and brightness Vo output from each of the adjustment means into a color signal as output data,
Take the configuration provided.
[0019]
The hue-based adjustment value calculation means includes means for outputting the hue adjustment value Hh, the saturation adjustment value Hs, and the brightness adjustment value Hv according to the characteristics set by the input hue Hi.
[0020]
The saturation adjustment value calculation means includes means for outputting the hue adjustment value Sh, the saturation adjustment value Ss, and the brightness adjustment value Sv according to the characteristics set by the input saturation Si.
[0021]
The lightness adjustment value calculation means has means for outputting according to the characteristics in which the hue adjustment value Vh, the saturation adjustment value Vs, and the lightness adjustment value Vv are set according to the input lightness Vi.
[0022]
The hue adjustment unit described above includes a unit that adjusts the hue Hi of the input data in accordance with Hh, Sh, and Vh that are the outputs of the adjustment value calculation units, and outputs the adjusted hue Ho.
[0023]
Further, the saturation adjusting means described above has means for adjusting the saturation Si of the input data according to Hs, Ss, and Vs that are the outputs of the respective adjustment value calculating means, and outputting the adjusted saturation So.
[0024]
Further, the lightness adjusting means described above has means for adjusting the lightness Vi of the input data according to Hv, Sv, Vv that are the outputs of the respective adjustment value calculating means, and outputting the lightness Vo after the adjustment.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0026]
FIG. 1 is a block diagram showing an example of the configuration of a color adjustment apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a color space converter that converts input color data Ri, Gi, Bi into hue Hi, saturation Si, and brightness Vi and outputs them, and 2 is output from the color space converter 1. The hue adjustment value calculator for outputting the hue adjustment value Hh, the saturation adjustment value Hs, and the lightness adjustment value Hv, 3 is input with the saturation Si output from the color space converter 1. Saturation adjustment value calculator for outputting hue adjustment value Sh, saturation adjustment value Ss, and brightness adjustment value Sv, 4 receives the brightness Vi output from color space converter 1, and receives hue adjustment value Vh, A lightness adjustment value calculator 5 for outputting the saturation adjustment value Vs and the lightness adjustment value Vv, 5 outputs the hue Hi output from the color space converter 1 from the adjustment value calculators 2, 3, 4. Color after adjustment according to hue adjustment values Hh, Sh, Vh The hue adjuster 6 that outputs Ho adjusts the saturation Si output from the color space converter 1 according to the saturation adjustment values Hs, Ss, and Vs output from the adjustment value calculators 2, 3, and 4. Then, the saturation adjuster 7 that outputs the adjusted saturation So, the brightness adjustment value 7 that is output from each of the adjustment value calculators 2, 3, and 4, and the brightness Vi that is output from the color space converter 1. A lightness adjuster 8 that adjusts according to Hv, Sv, and Vv and outputs adjusted lightness Vo, and outputs the adjusted hue Ho, saturation So, and lightness Vo to color signals Ro, Go, and Bo as output data. It is a color space inverse converter that converts and outputs.
[0027]
In the configuration shown in FIG. 1, input color data (color signals) Ri, Gi, Bi is sent to the color space converter 1 and converted into hue Hi, saturation Si, and brightness Vi. This conversion is executed using a color space conversion formula from RGB to HSV, which is a well-known technique.
[0028]
The adjustment value calculator 2 receives the hue Hi and outputs a hue adjustment value Hh, a saturation adjustment value Hs, and a lightness adjustment value Hv set as parameters. In the adjustment value setting, the difference between the value after adjustment and the value before adjustment is stored in a memory as a lookup table (LUT). In this way, it is possible to adjust not only the hue but also the saturation and brightness by the input hue. FIG. 3 is an example showing the relationship between hue and brightness among the relationship between the input value and the adjustment value set in the adjustment value calculator 2. The brightness adjustment value for the input hue is expressed as a plus or minus value with zero as the difference before and after adjustment. The brightness adjustment value increases the brightness when the hue is yellow and decreases the brightness when the hue is blue-violet. By giving Hv, natural harmony can be realized. In addition to the difference as the adjustment value, it is also possible to handle the ratio between the value after adjustment and the value before adjustment. In this case, the processing content in the adjuster described later is changed. Also, the adjustment value can be referred to by performing a function F (H) in addition to the LUT.
[0029]
The adjustment value calculator 3 receives the saturation Si, and outputs a hue adjustment value Sh, a saturation adjustment value Ss, and a brightness adjustment value Sv set as parameters. As with the adjustment value calculator 2, the adjustment value is set by giving the difference or ratio before and after adjustment as an LUT or function. In this way, not only the saturation but also the hue and brightness can be adjusted by the input saturation. FIG. 4 is an example showing the relationship between the saturation and the lightness among the relationship between the input value set in the adjustment value calculator 3 and the adjustment value. The brightness adjustment value with respect to the input saturation is expressed as a positive value based on 1 as a ratio before and after the adjustment, and a brightness adjustment value Sv that increases the brightness in an intermediate saturation area is given. FIG. 5 represents a tone change according to the adjustment example of FIG. 4, and by this processing, the tones of p, ltg, g, and dkg are adjusted in the directions of p, p, ltg, and g, respectively, and the tone of ash Can be adjusted to a lighter tone. Further, depending on which of the difference and the ratio is handled as the adjustment value, the processing content in the adjuster described later changes.
[0030]
The adjustment value calculator 4 receives the lightness Vi and outputs a hue adjustment value Vh, a saturation adjustment value Vs, and a lightness adjustment value Vv set as parameters. As with the adjustment value calculator 2, the adjustment value is set by giving the difference or ratio before and after adjustment as an LUT or function. In this way, not only the lightness but also the hue and saturation can be adjusted by the input lightness. FIG. 6 is an example showing the relationship between brightness and saturation among the relationship between the input value set in the adjustment value calculator 4 and the adjustment value. The saturation adjustment value with respect to the input lightness is expressed with reference to zero as the difference before and after the adjustment, and a saturation adjustment value Vs that lowers the saturation of the entire lightness with the intermediate lightness being maximized is given. FIG. 7 expresses a tone change according to the adjustment example of FIG. 6, and by this processing, the strong tone becomes weak and the tone can be adjusted to a calm tone. Further, depending on which of the difference and the ratio is handled as the adjustment value, the processing content in the adjuster described later changes.
[0031]
The hue adjuster 5 adjusts the hue Hi output from the color space converter 1 in accordance with the hue adjustment values Hh, Sh, and Vh output from the adjustment value calculators 2, 3, and 4, respectively. Output Ho. As an example of adjustment, addition is performed when the hue adjustment value represents a difference before and after the adjustment, and multiplication is performed when the hue adjustment value represents a ratio. That is, when all of the hue adjustment values Hh, Sh, and Vh are differences, Ho = Hi + Hh + Sh + Vh, and when all of the hue adjustment values Hh, Sh, and Vh are ratios, Ho = Hi * Hh * Sh * Vh. It becomes. When Hh is a ratio and Sh and Vh are differences, adjustment is performed by calculating Ho = Hi * Hh + Sh + Vh or Ho = (Hi + Sh + Vh) * Hh.
[0032]
The saturation adjuster 6 adjusts the saturation Si output from the color space converter 1 according to the saturation adjustment values Hs, Ss, and Vs output from the adjustment value calculators 2, 3, and 4, respectively. The later saturation So is output. Specifically, as in the case of the hue adjuster 5, addition is performed when the saturation adjustment value represents a difference, and multiplication is performed when the saturation adjustment value represents a ratio. That is, when all of the saturation adjustment values Hs, Ss, and Vs are differences, So = Si + Hs + Ss + Vs. When all of the saturation adjustment values Hs, Ss, and Vs are ratios, So = Si * Hs * Ss. * Vs.
[0033]
The lightness adjuster 7 adjusts the lightness Vi output from the color space converter 1 in accordance with the lightness adjustment values Hv, Sv, and Vv output from the adjustment value calculators 2, 3, and 4, respectively. Vo is output. Specifically, as in the case of the hue adjuster 5, addition is performed when the brightness adjustment value represents a difference, and multiplication is performed when the ratio represents a ratio. That is, when all of the brightness adjustment values Hv, Sv, and Vv are differences, Vo = Vi + Hv + Sv + Vv. When all of the brightness adjustment values Hv, Sv, and Vv are ratios, Vo = Vi * Hv * Sv * Vv. It becomes.
[0034]
Finally, the adjusted hue Ho, saturation So, and brightness Vo output from the hue adjuster 5, saturation adjuster 6, and brightness adjuster 7, respectively, are sent to the color space inverse converter 8 and are output data. It is converted into color signals Ro, Go, Bo and output. This conversion is executed using a well-known color space conversion formula as the inverse conversion of the color space converter 1.
[0035]
In the above-described embodiment, RGB is exemplified as the input / output color space. However, the present invention is not limited to this, and can be used in a color space such as CMY or YCbCr.
[0036]
【The invention's effect】
As described above, according to the present invention, for hue, saturation, and brightness color adjustment, hue, saturation, and brightness adjustment based on input hue, hue, saturation, and brightness adjustment based on input saturation, and input brightness Hue, saturation, and lightness can be adjusted by adjusting the hue, saturation, and lightness of natural hues that require lightness adjustment by hue, and tone adjustment that requires combined adjustment of saturation and lightness. This is advantageous in that it is possible to perform color adjustment which is difficult with independent adjustment.
[0037]
In addition, by adjusting the saturation adjustment value by hue, brightness adjustment value, hue adjustment value by saturation, brightness adjustment value, hue adjustment value by brightness, and saturation adjustment value to zero, the conventional hue, saturation, brightness Gradation conversion can be realized, and there is an effect that characteristics of the HSV color space in which hue, saturation, and brightness can be adjusted independently can be maintained.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of a configuration of a color adjustment apparatus according to an embodiment of the present invention.
FIG. 2 is a conceptual diagram for explaining a basic concept of tone adjustment.
FIG. 3 is an explanatory diagram showing an example of a relationship between hue and brightness among adjustment value settings of an adjustment value calculator based on hue according to an embodiment of the present invention.
FIG. 4 is an explanatory diagram showing an example of a relationship between saturation and lightness among adjustment value settings of an adjustment value calculator based on saturation in an embodiment of the present invention.
FIG. 5 is an explanatory diagram showing an example of a tone change according to the adjustment example of FIG. 4;
FIG. 6 is an explanatory diagram showing an example of a relationship between lightness and saturation among adjustment value settings of an adjustment value calculator based on lightness according to an embodiment of the present invention.
7 is an explanatory diagram showing an example of a tone change according to the adjustment example of FIG. 6; FIG.
FIG. 8 is a block diagram for explaining a basic concept of a conventional color conversion processing apparatus.
FIG. 9 is a block diagram for explaining a basic concept of a conventional color adjustment processing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Color space converter 2 Adjustment value calculator by hue 3 Adjustment value calculator by saturation 4 Adjustment value calculator by brightness 5 Hue adjuster 6 Saturation adjuster 7 Lightness adjuster 8 Color space inverse converter 40 Coordinate conversion circuit 42, 48 Selection circuit 44 CPU address bus 46 Function conversion circuit 50 CPU data bus 52 Inverse coordinate conversion circuit 101 Profile 102 Color system conversion unit 103 Target pixel setting unit 104 Histogram creation unit 105 Achromatic color range specification unit 106 Maximum histogram search unit 107 distance calculation reference designation unit 108 color conversion function designation unit 109 color conversion unit 110 overall control unit 111 color system inverse transformation unit

Claims (4)

Color space conversion means for converting the color signal as input data into hue Hi, saturation Si, and brightness Vi;
A hue adjustment value calculating unit that outputs the hue adjustment value Hh, the saturation adjustment value Hs, and the lightness adjustment value Hv by using the hue Hi output from the color space conversion unit;
A saturation adjustment value calculation unit that outputs the hue adjustment value Sh, the saturation adjustment value Ss, and the lightness adjustment value Sv by using the saturation Si output from the color space conversion unit;
A lightness adjustment value calculating means for outputting a hue adjustment value Vh, a saturation adjustment value Vs, and a lightness adjustment value Vv by using the lightness Vi output from the color space conversion means;
Hue adjustment means for adjusting the hue Hi of the input data using the hue adjustment values Hh, Sh, Vh output from the respective adjustment value calculation means;
Saturation adjustment means for adjusting the saturation Si of the input data using the saturation adjustment values Hs, Ss, Vs output from each of the adjustment value calculation means;
Brightness adjustment means for adjusting the brightness Vi of the input data using the brightness adjustment values Hv, Sv, Vv output from the respective adjustment value calculation means;
Color space inverse conversion means for converting the adjusted hue Ho, saturation So, and brightness Vo output from each of the adjustment means into a color signal as output data,
A color adjusting device comprising: In claim 1,
The hue adjustment value calculation means includes means for outputting according to the characteristics in which the hue adjustment value Hh, the saturation adjustment value Hs, and the lightness adjustment value Hv are set according to the input hue Hi. Adjustment device. In claim 1,
The adjustment value calculation means by saturation described above has means for outputting according to the characteristics in which the hue adjustment value Sh, the saturation adjustment value Ss, and the lightness adjustment value Sv are set by the input saturation Si. Color adjustment device. In claim 1,
The lightness adjustment value calculation means includes a means for outputting according to characteristics in which the hue adjustment value Vh, the saturation adjustment value Vs, and the lightness adjustment value Vv are set according to the input lightness Vi. Adjustment device.

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