JP2537997B2 - Color adjustment device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color adjusting device for performing color adjustment of a color original when a color original is reproduced by a hard copy device from three color separation signals of a color scanner. is there.

2. Description of the Related Art Conventionally, in a device that reproduces a color original as a hard copy, the same color correction process is performed on the entire screen. For this reason, it has been difficult to reproduce only a color that humans have as an image, such as a skin color, that is, a memory color, into a color that is preferable to humans. It is possible to solve this by determining the area on the screen and changing the process for each part (for example, human face, hair, fruit), but it is necessary to divide the image area, which is done manually. It is also very difficult to do automatically. Therefore, a method has been proposed in which the area determination is performed in the color space instead of on the screen. This is a technique for determining which region in the color space the color input to the device belongs to and changing the content of color reproduction processing according to the determination result. For example, the technique described in JP-A-60-91770. There is
To briefly explain the configuration, a memory color correction unit is connected to the output side of the masking ROM that stores the color correction content via a UCR (under color removal) unit, and the output signals C (cyan) and M (magenta) of the masking ROM are connected. ), Y (yellow), only a certain range is determined to be a color area corresponding to the memory color in the color space, and the corresponding ROM content is C, M, It is to be replaced with the Y combination.

Problems to be Solved by the Invention However, the conventional techniques have the following problems.

(A) Since the memory color reproduction area such as the skin color is set discontinuously in the color space, when the input color is located at the boundary of the area, the output color becomes discontinuous and the false color appears on the reproduced image. The contour is generated. Also, the ideal combination of C, M, and Y for memory color reproduction is 1 for each color area.
Since only one type is set and an ideal one color is reproduced in this area, a slight change in color tone and gradation of the original image are destroyed.

(B) The target area for memory color reproduction is judged not by the three-color separated signal of the input color but by the C, M, Y values after the masking process, so if the masking coefficient is changed, the memory color is changed. It is necessary to change the target area for reproduction at the same time, and it is difficult to configure both independently.

In the above example, the target area for memory color reproduction such as skin color is
Although the method of automatically determining and automatically reproducing an ideal color has been described, the ideal color has a large individual difference. Regarding skin color, it is reported that Japanese people imagine a more pinkish color than a real skin color, but Westerners prefer a yellow color to a real skin color.

Also, unlike the case of a television that always emits a stable color due to the phosphor, in the color reproduction of hard copy, the reproduced color slightly changes depending on various environmental conditions, and ideal C, M,
The Y combination does not always reproduce the ideal color.

From the above reason, it is understood that addition of some color adjustment function is effective even in the case of memory color reproduction, but most of the conventional color adjustment functions act on the entire color space. The adjustment is to make these screens brighter, darker, or reddish, and does not serve the purpose here of adjusting only the color of a specific area. Taking television color adjustment as an example, turning the hue knob to add a reddish tint to the skin tone certainly improves the skin tone, but at the same time, the hue of the entire screen changes evenly. At this time, due to the property that a color having a higher hue saturation has a larger amount of absolute color change with an equal change in hue angle, for example, an unnatural phenomenon occurs in which a bright yellow fruit is colored extremely red.

In view of the above problems, the present invention automatically determines the color of the memory color reproduction target area determined independently of the masking while maintaining the natural gradation on the reproduced image, and The user can easily adjust only the near color region to a desired color tone, and as a result, it is possible to reproduce the color of the memory color preferable for each user.

Means for Solving the Problems In order to achieve the above object, a technical solution of the present invention is to connect a three-color separation signal of a scanner to develop a color developing system conversion unit, a memory color adjusting unit, and a color developing system inverse conversion. A new unit is installed, and an existing masking unit is installed in the subsequent stage to send a signal to a hard copy device. The color development system conversion unit uses a three-color separation reflectance signal R ( Red), G (green), B (blue), or the three-color density signal Dr obtained by logarithmically converting it
It is composed of a table for converting (red density), Dg (green density), and Db (blue density) into three quantities of hue, lightness, and saturation which are convenient for color adjustment.

Further, the memory color adjustment unit includes a table for measuring and hue for designating a memory color reproduction target area, a multiplier, an adder, and a memory color adjustment signal generator used by a person for color adjustment.

Further, the color-developing system inverse conversion unit is composed of a table for converting the three amounts of color image, lightness, and saturation into three signals (usually three color density signals) input to the masking unit.

The masking unit comprises a table for generating drive signals C, M, Y or C, M, Y, K of the hard copy device from the inputted three color density signals.

Action The main point of the present invention is to perform color adjustment by moving only the vicinity of the memory color reproduction target area such as the skin color area to another color with the above configuration, while maintaining the natural gradation on the reproduced image, The color of the memory color reproduction target area that is determined independently of masking is automatically determined, and the user can easily adjust only the color area close to that color to the desired color tone, and as a result, for each user This makes it possible to reproduce a preferable memory color.

Practical Example The concept of the color adjusting apparatus of the present invention will be described below.

The color signal separated into three colors by the scanner is converted into three amounts of hue (H), lightness (L), and saturation (S) by the developer conversion circuit.

Since the present invention performs color adjustment by moving only the vicinity of the memory color reproduction target area such as the skin color area to another color, first, the memory color reproduction target area (hereinafter referred to as the target area)
Must be specified.

A method of specifying the target area will be described with reference to FIG. Since the target area is specified by chromaticity and is not related to lightness, only H and S may be used for this specification. Also, in color adjustment, in order to eliminate discontinuity at the boundary with other colors, the amount of color adjustment movement is large at the center of gravity (Ht, St) of the target area.
The amount of movement gradually decreases as the distance from the center of gravity increases. The magnitude of the color adjustment amount is represented by 0 to 1, and W (H, S) (0 ≦ W ≦ 1) is a function of H and S. Furthermore, this amount is decomposed into H-axis and S-axis, and W (H, S) = Wh (H) × Ws (S) (1st equation) (0 ≦ Wh, Ws ≦ 1) Wh (H), in the target area specification table of
Ws (S) is memorized, the product of both is calculated, and W
Find (H, S). Note that W (H, S) is the center of gravity (H
t, St) takes 1 and becomes 0 outside the target area, and in order to make a smooth decrease between them, in FIG. 3 (a), (b)
As shown in, Wh (H) and Ws (S) are Ht and St, respectively.
And take a function form that decreases smoothly.

Next, how to adjust the color of the center of gravity of the target area will be described with reference to FIG. Since the color adjustment is performed using the coordinates of the color developing system, the color is rotationally moved in the hue (H) direction to adjust the hue, and the hue adjustment is moved to the saturation (S) direction to make the color vivid. Alternatively, the saturation adjustment for dropping only the color, the brightness adjustment for moving the color in the lightness (L) direction to make it brighter or darker, and the combination adjustment thereof are performed.
In the H and S directions, ΔH and ΔS are increased or decreased, and in the L direction, L is multiplied by a proportional constant KL for adjustment. Here, changes in hue and saturation do not cause unnaturalness in the reproduced image even if they are additively increased or decreased if continuity is maintained, but a simple increase or decrease in lightness is a dynamic range of the brightness of the reproduced image. It is easy to be unnatural because it reduces. Therefore, in order to reduce the brightness adjustment amount in the dark part and increase it in the bright part, the adjustment that multiplies the proportional constant is adopted. Furthermore, L is saved outside the target area, and KL × L is adjusted at the center of gravity of the target area. However, the proportional constant is set to W to maintain continuity between them.
Use (H, S) to change.

Expressing the above with the formula, H ′ = H + (DH) × W (H, S) …… (Second formula) S ′ = S + (DS) × W (H, S) …… (Third formula) L = {(KL-1) × W (H, S) +1} × L = (KL-1) × W (H, S) × L + L (Formula 4), where H, L, S Is the coordinate value of the color before adjustment in the HLS space, H ', L', S'is the coordinate value after adjustment, and DH, DS, KL are the parameters specified as the amount of adjustment for the center of gravity of the target area. The rotation angle of hue (± 0 ° to 360 °), the amount of change in saturation, and the constant of proportional change in lightness are shown. Therefore, by this adjustment, W (H, S) = 1 at the center of gravity (Ht, St) of the memory color target area, so that only DH and DS are changed in H and S, and KL times are changed in L. This change decreases with a decrease in W (H, S) at a position deviated from the center of gravity of the memory color reproduction region, and W changes outside the memory color reproduction region.
Since (H, S) = 0, H '= H, L' = L, S '= S, and no adjustment is performed.

Here, how to actually perform the color adjustment will be described taking the skin color adjustment as an example. It is assumed that the center of gravity of the skin color area in the HLS space has been calculated in advance and set to Wh (H) and Ws (S). If the flesh color of the input color original is very dark and yellowish, DH = -10 (°), KL =
By specifying 1.5, DS = 0, etc., it is possible to change the flesh color in the red direction and simultaneously brighten it, and it is possible to make an adjustment that does not affect other colors in the image.

In the above process, first, the memory color reproduction target area can be adjusted to a preferred direction in the HLS space, and then H ', L', S'are input to the masking unit by the color-developing system inverse conversion unit. Dr, Dg, Db are converted into C, M, Y, K quantities that drive the hard copy device by masking operation,
In this way, the memory color adjustment in the HLS space is reflected on the reproduced image of the hard copy.

According to the present invention, it is possible to locally adjust the color of a skin color area or the like while maintaining the naturalness on the reproduced image by the above method, and in that case, the color can be handled by parameters of hue, saturation, and brightness. it can. Further, since the memory color adjusting unit is installed in front of the masking unit, there is no particular effect when changing the masking unit because the characteristics of the hard copy device have changed, and the memory color adjusting unit can be configured completely independently.

An embodiment of a specific apparatus for realizing the color adjusting method of the present invention will be described below with reference to FIG. The reflectance or density signal 1 separated into three colors by the color scanner is converted into H, L, S signals 3 in the color development system conversion unit 2, and H, S
The signals are input to the target area specifying H table 4 and the target area specifying S table, respectively. In each table 4 and 5, the barycentric coordinate value (Ht, S
Wh (H), Ws (S) as shown in Fig. 3 based on t)
Is stored. Those Wh (H), Ws
The signal of (S) is multiplied by the multiplier 6 and the calculation of the first equation is performed, resulting in the W (H, S) signal 7. Memory color adjustment signal generator 8
Is the color adjustment value in each direction of H, L, S at the center of gravity of the target area, that is, the size of DH, DS, KL (including positive and negative) of the second to fourth equations is specified. Signal 9, DS signal 10, KL signal 11
Occurs. W (H, S) signal 7, DH signal 9 and H signal are
The multiplier 12 and the adder 15 perform the calculation of the second equation to obtain the H'signal. The W (H, S) signal 7, the DS signal 10 and the S signal are subjected to the calculation of the third equation by the multiplier 13 and the adder 16 to become the S signal. W (H, S) signal 7, KL signal 11 and L signal are multiplied by multiplier 1
The calculation of the fourth equation is performed by 4 and the adder 17 to obtain the L'signal. The adjusted H'L'S 'signal 18 is converted into an adjusted three-color separation density signal 20 by the color developing system inverse conversion unit 19, and the masking unit 21 drives C, M, and C for driving the hard copy device.
It can be converted into a Y signal or a C, M, Y, K signal.

EFFECTS OF THE INVENTION As described above, the present invention is capable of locally performing color adjustment on a region of a color to be reproduced such as a skin color region while maintaining the naturalness on a reproduced image. It can be handled with parameters of saturation and brightness. Further, since the memory color adjusting unit is installed in front of the masking unit, it is not particularly affected when changing the masking unit due to changes in the characteristics of the hard copy device, and has the effect that it can be configured completely independently. .

[Brief description of drawings]

FIG. 1 is a block connection diagram in an embodiment of a color adjusting apparatus of the present invention, FIG. 2 is a conceptual diagram showing a method of designating a memory reproduction area in the present invention in a color developing system HLS space, and FIG. FIG. 4 is a conceptual diagram showing the contents of a hue and saturation table for designating a memory color reproduction target area, and FIG. 4 is a conceptual diagram showing a color adjustment method in a color developing system HLS space according to the present invention. 2 ... Development system conversion unit, 4 ... H (hue) memory color reproduction target area designation table, 5 ... S (saturation) memory color reproduction target area designation table, 6 ... Multiplier, 8 ... … Memory color adjustment signal generator, 12 to 14 …… Multiplier, 15 to 17 …… Adder, 19 …… Reverse color conversion unit, 21 …… Masking unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidehiko Kawakami 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Prefecture Matsushita Giken Co., Ltd. Matsushita Giken Co., Ltd. (56) References JP-A-46-554 (JP, A) JP-A-59-163962 (JP, A) JP-A-63-208981 (JP, A) JP-A Sho 63-219271 (JP, A) JP 64-16658 (JP, A) JP 2-51979 (JP, A)

Claims (5)

(57) [Claims] 1. A three-color separated reflectance signal R (red), G (green), B (blue) obtained from the color scanner connected to the three-color separated signal of the color scanner, or a logarithmic conversion thereof. Three-color density signals Dr (red density), Dg (green density), Db (blue density) are set to 3 of the color development system of hue, brightness, and saturation.
A color-developing system conversion unit for converting the color-developing amount into a quantity is used to specify the memory color reproduction target area by using the three quantities of the color-developing system, and the continuity of the three quantities of the color-developing system in the memory-color reproduction target area is maintained. A memory color adjustment unit for selectively performing color adjustment while maintaining the color, a color reversal conversion unit for converting the three amounts of the color revelation system after color adjustment into three color density signals, and an output of the color reversal system conversion unit A color adjusting device having a masking unit for converting a hard disk drive signal into a hard copy device drive signal. 2. The color development system conversion unit comprises three color separation reflectance signals R (red), G (green), B (blue) obtained from a color scanner, or a three color density signal Dr ( 2. The color adjusting apparatus according to claim 1, further comprising a table for converting red density), Dg (green density), and Db (blue density) into three quantities of hue, lightness, and color saturation. 3. A memory color adjustment unit comprises a saturation and hue table for specifying a memory color reproduction target area, a multiplier, an adder, and an adjustment signal generator used by humans for color adjustment. The amount of adjustment is large in the center of gravity of the color area that you want to reproduce as a color, and the amount of adjustment decreases continuously as you move away from the center of gravity, and the center of gravity of this color area is adjusted using the hue, brightness, and saturation parameters of the developer system. The color adjusting device according to claim 1, wherein 4. The color-developing system inverse conversion unit has a table for converting three values of hue, lightness, and saturation into three-color density signals to be input to the masking unit. Color adjustment device. 5. A masking unit receives drive signals C (cyan) and M of a hard copy device from input three color density signals.
The color adjusting apparatus according to claim 1, further comprising a table for generating (magenta), Y (yellow) or C, M, Y, K (black).