JPH0296477A - Color regulating method - Google Patents

Abstract

PURPOSE:To reproduce a preferable storage color at every user by moving only a storage color regenerative objective area vicinity such as a flesh color to the other color. CONSTITUTION:A density signal 1 by means of a color scanner is converted into H, L and S signals 3 by a development system converting unit 2, and the H and S signals are respectively inputted to an objective area designating H table 4 and an S table 5. In the tables 4 and 5, prescribed values are stored based on the gravity center coordinate values in an HLS space in the objective area such as the flesh color. These signals are multiplied 6 to be signals 7. A storage color regulating signal generator 8 designates the color regulating value in respective H, L and S directions at the objective area gravity center, and generates signals 9 to 11. Prescribed calculations are executed for the respective signals by multipliers 12 to 14 and adders 15 and 17. In addition, H', L' and S' signals 18 after regulation are converted into three color separating density signal 20 after regulation by a development system inverting unit 19, and made into a hard copy device driving CMY or a CMYK signal in a masking unit 21.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color adjustment method for performing color adjustment of color signals when a color original is reproduced using a Hartcoby device from three-color separation signals of a color scanner. It is.

2. Description of the Related Art Conventionally, in an apparatus that reproduces a color original as a hard copy, the same color correction processing is applied to the entire screen. For this reason, it has been difficult to reproduce only colors that humans have in mind, such as skin tones, that is, memory colors, into colors that humans prefer. It is possible to solve this problem by determining the area on the screen and changing the processing for each part (for example, a person's face, hair, fruit), but it is necessary to divide the image into areas.
This is very difficult to do manually or automatically. Therefore, a method has been proposed in which area determination is performed within the color space rather than on the screen. This is a technology that determines to which region in the color space the color input to the second position belongs, and changes the content of color reproduction processing according to the determination result. To briefly explain the configuration, a memory color correction unit is connected to the output side of the masking IM)M that stores the color correction contents via a UC'(undercolor removal) unit, and the masking R
, OM output signals C (cyan), M (magenta), Y (
It is determined that only a certain range of the combinations of (Yellow-) corresponds to the memory color in the color space, and the corresponding R
This replaces the OM contents with a combination of C, M, and Y that produces ideal color reproduction.

Problems that the invention aims to solve However, the conventional technology has the following problems.

(A) Since the memory color reproduction area such as skin color is set discontinuously within the color space, when the manually created color is located at the boundary of the area, the output color will be discontinuous. False contours occur.

Also, C and M are ideal for reproducing memory colors.

Only one type of Y combination is set for each color area, and since one ideal color is reproduced in this area, subtle changes in color tone and gradation of the original image are destroyed.

(B) The target area for memory color reproduction is 3 of the input colors.
Since the determination is made based on the C2M and Y values after masking processing, rather than color separation signals, when changing the masking coefficient, it is necessary to change the target area for memory color reproduction at the same time, and it is not possible to configure both independently. Have difficulty.

In the example above, we explained a method in which the target area for memory color reproduction, such as skin tone, is automatically determined and automatically reproduced as an ideal color. Hey. Regarding skin color, it has been reported that Japanese people imagine a pinkish color rather than a real skin color, while Westerners imagine and prefer a yellow color rather than a real skin color.

Also, unlike the case of television, which uses phosphors to emit stable colors at all times, in hard copy color reproduction, the reproduced colors vary slightly depending on various environmental conditions, and the ideal C, M
, Y does not necessarily reproduce an ideal color.

For the above reasons, it can be seen that adding some kind of color adjustment function is effective even in the case of memory color reproduction, but most conventional color adjustment functions act on the entire color space.

These adjustments make the screen brighter, darker, or reddish, and do not serve the purpose here of adjusting only the color of a specific area. Taking color adjustment on a television as an example, if you turn the hue knob to add a reddish tinge to a yellowish skin tone, the skin tone will certainly be improved, but at the same time the hue of the entire screen will change uniformly. At this time, due to the fact that the absolute amount of change in high-chroma colors is large when the hue angle is changed, unnatural things occur, such as bright yellow fruits becoming extremely red.

In view of the above-mentioned problems, the present invention automatically determines the color of the memory color reproduction target area, which is determined independently of masking, while maintaining the natural gradation of the reproduced image. The user can easily adjust only the close color areas to any color tone, and as a result, it is possible to reproduce the memory color preferred by each user.

Means for Solving the Problems In order to achieve the above problems, the technical solution of the present invention is as follows:
A color development system conversion unit, a memory color adjustment unit, and a color development system inverse conversion unit are newly installed by connecting to the three-color separation signal of the scanner, and the existing masking unit is installed at the subsequent stage to send signals to the hard copy device. The color developing system conversion unit is configured to send three color separation reflectance signals R (red), G (green), and B (pull) obtained from the scanner.
, or logarithmically converted three color density signals Dr (red density), Dg (green density), and Db (blue density) into three color developer quantities convenient for color adjustment: hue, brightness, and saturation. Consists of tables for.

The memory color adjustment unit includes a search power and hue table for specifying a memory color reproduction target area, a multiplier, an adder, and a memory color adjustment signal generator used by humans for color adjustment.

In addition, the color developer system inverse conversion unit has three functions: hue, brightness, and saturation.
It consists of a table that converts the amount into a masking unit and 3 human-powered signals (usually 3-color deep signals).

The masking unit extracts eight signals from the input three color density signals.
Drive signals C, M, ゛Y or C, M of the copying device
, Y, and K. The key point of the present invention is that in addition to the above configuration, by moving only the vicinity of the memory color reproduction target area, such as the skin color area, to another color,
This is a color adjustment that automatically determines the color of the memory color reproduction target area, which is determined independently of masking, while maintaining the natural gradation of the reproduced image, and only selects the color area that is close to that color. The user can easily adjust the color tone freely, and as a result, it is possible to reproduce the memory color preferred by each user.

EXAMPLES Below, the concept of the color adjustment method of the present invention will be explained.

A color signal separated into three colors by a scanner is converted into three quantities: hue (H), lightness (L), and saturation (S) by a color developer conversion circuit. Here, the model used for the conversion is r(I(LS), which is easy to convert from OB. Although we assumed the bihexagonal pyramid model, it is not particularly specified. For example, L can also be Y of YIQ coordinates,
You can also use L * of L book a * b * space, etc., and H
, S consider polar coordinates on the IQ plane or a*b* plane that represents chromaticity, and the distance from the H11 quantity to the angle for specifying the hue is S.
And it is sufficient.

The present invention adjusts the color by moving only the vicinity of the memory color reproduction target area, such as the skin color area, to another color.
First, it is necessary to specify a memory color reproduction target area (hereinafter referred to as a target area).

This method of specifying the target area will be explained using FIG. 2. The target area is specified by chromaticity and is unrelated to brightness, so only ■] and S may be used for this specification. Also, when adjusting colors, in order to eliminate discontinuities at boundaries with other colors, the amount of movement for color adjustment is increased at the center of gravity (tt, st) of the target area, and the amount of movement is gradually decreased as you move away from the center of gravity. do. The size of this color adjustment amount is expressed as O~1, H,
As a function of S, W(1-I,S) (0≦W≦
1). Furthermore, this quantity is decomposed into the H axis and the S axis, and W(
H, S) = Wh(H) x Ws (S) ・(Formula 1)
(H) and Ws (S) are stored, and the product of both is calculated to obtain W(H,S). Furthermore, W(H,S
) takes 1 at the center of gravity of the target area (Ht, st), becomes 0 outside the target area, and decreases smoothly between them, so wh( H
) and Ws(S) are 1 for Ht and St, respectively.
, takes the form of a smoothly decreasing function.

Next, how to adjust the color of the center of gravity of the target area will be explained using FIG. 4. Since color adjustment is performed using the coordinates of the color development system, the color is rotated in the hue (H) direction,
Hue adjustment to change the color tone, saturation adjustment to make colors more vivid or less tint by moving towards saturation (8), and brightness adjustment to make colors brighter or darker by moving towards lightness (L). , and adjust these combinations. H,S
In the direction, increase or decrease ΔH2ΔS, and in the L direction, increase or decrease ΔH2ΔS.
Adjust by multiplying by the proportionality constant KL. As long as changes in hue and saturation are maintained, additive increases and decreases will not cause much unnaturalness in the reproduced image, but when it comes to brightness, simple increases and decreases will significantly affect the brightness of the reproduced image. It tends to look unnatural because it reduces the range. Therefore, we adopted an adjustment method that multiplies the brightness adjustment amount by a proportionality constant in order to reduce the amount of brightness adjustment in dark areas and increase it in bright areas.Furthermore, we conserved L outside the target area and adjusted KLxL at the center of gravity of the target area. , the proportionality constant is changed using W(H,S) so as to maintain continuity between them.

If the above is expressed as a formula, H=H0(DH) xW(H,S)...(Second
Formula) S-8+(DS)XW(i(,S) ,,,
,, (3rd equation) L = ((KL-1) xW(H,S
)+11xL(KL-1) xW(H,S) x L+
L...(4th formula). where) −f, L,
S is the color P [coordinate values in LS space, H, L, S
is the coordinate value after adjustment, DH, DS, and KL are parameters specified as the amount of adjustment to the center of gravity of the target area, and are the rotation angle of hue (10 to 360), amount of change in saturation, and change in brightness, respectively. It shows the constant of proportionality. Therefore, with this adjustment, the center of gravity (Ht, St
) is W(H,5)-1, so H,S[DH.

A change of only DS occurs, and a change of L times KL occurs. This change decreases as W (H, S) decreases at positions away from the center of gravity of the memory color reproduction area, and outside the memory color reproduction area, W (H, S ) o nanote l1 = H,
L'-L, S'=8 Toner C adjustment will not be performed at all.

Here, we will explain how to actually perform color adjustment using skin color adjustment as an example. The I (center of gravity in the LS space) of the skin color area is calculated in advance and set to Wh (H) and Ws (S). If the skin color of the input color original is very dark and yellowish. DH
--10('), KL=1.5, DS=0
By specifying things like this, you can make adjustments that change the skin color in the direction of the light and brighten it at the same time, without affecting other colors in the image.

In the above process, first, the memory color reproduction target area can be adjusted in a preferable direction in )-H,S space, and then x-(,r,'
.

Three color separation densities (Dr, Dg, DI) where S is manually inputted to the masking unit by the color developer inverse conversion unit
It becomes the C, M, Y, K capacity that drives the hard copy device by the masking operation, and in this way, the memory color adjustment in the hole S space is reflected on the reproduced image of the 1-F copy. That will happen.

The present invention enables local color adjustment of skin tone areas, etc., while maintaining the naturalness of the reproduced image using the above method. can. Still, since the memory color adjustment unit is installed before 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 can be configured completely independently.

Hereinafter, an embodiment of a specific apparatus for realizing the color adjustment method of the present invention will be described with reference to FIG. The reflectance or density signal l separated into three colors by the color scanner is converted to If in the color developer conversion unit 2.

The L and S signals are converted into L and S signals 3, and the H and S signals are input to a target area designation table 4 and a target area designation S table 5, respectively. Tables 4 and 5 are pre-filled with 1-(barycentric coordinates in L8 space (l(t,
Wh (H) as shown in Figure 3 based on St)
, Ws (S) are stored.

The signals Wh (H) and Ws (S) are multiplied by a multiplier 6 to calculate the second equation, resulting in a W(H,S) signal 7. The memory color adjustment signal generator 8 calculates the magnitude (including positive and negative) of DH and DS in the target area 1 (mental color adjustment values in H, L, and S directions, that is, the DH and DS of the second to fourth equations). It generates DH signal 9, DS signal 10, and KL signal 11.W(H,S) signal 7, DH signal 9, and H
The signal is calculated by the second equation by the multiplier 12 and the adder 15 and becomes 1 (signal).

W(H,S) signal 7 and DS signal]0 and S signals are subjected to calculation according to the third equation by a multiplier 13 and an adder 16 to become an S signal. The W(H,8) signal 7, the KL signal 11, and the L signal are subjected to calculation according to equation 1 by the multiplier 14 and the adder 17, and become the L signal. After adjustment) ('L'S' signal 18
is converted into an adjusted three-color separation density signal 20 in the color developer system inverse conversion unit 19, and then converted into a C, M, Y signal for driving a hard copy device or a C, M, Y signal for driving a hard copy device in a masking unit 21.
M, Y, can be converted into signals.

Effects of the Invention As described above, the present invention is capable of locally adjusting the color area of a color that is desired to be reproduced as a memory color, such as a skin tone area, while maintaining the naturalness of the reproduced image. saturation,
It can be handled with the brightness parameter. In addition, since the memory color adjustment unit is installed before 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 advantage that it can be configured completely independently. .

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of a memory color adjustment device that implements the color adjustment method of the present invention, and Fig. 2 is a color developing system).
II.A conceptual diagram showing a method for specifying a memory color reproduction area in the present invention in 8 space. Fig. 3 is a conceptual diagram showing the contents of a table for hue and saturation for specifying a memory color reproduction target area in the present invention. 4 are conceptual diagrams showing a color adjustment method in the color developer system I (LS space) of the present invention. 2... Color developer system conversion unit, 4... Memory color reproduction for H (hue) Target area specification table, 5... Memory color reproduction target area specification table for S (saturation), 6... Multiplier, 8
. . . Memory color adjustment signal generator, 12 to 14 . . . Multiplier, 15 to 17 . . . Adder, 19 . Name of agent: Patent attorney Shigetaka Awano and 1 other person1
Figure 4 Column 19 Filling in Figure 2 - 11 *Colored ship unit 1111 Figure 2 (clL)

Claims (5)

[Claims] (1) Connected to the three color separation signals of the color scanner, it has a color development system conversion unit, memory color adjustment unit, and color development system inverse conversion unit, and an existing masking unit is installed at the subsequent stage, and the hardware A color adjustment method that sends a color signal to a copying device and locally adjusts the color only in the area corresponding to the color that humans remember in color space. (2) The color developing system conversion unit is a three-color separated reflectance signal R (red) and G (green) obtained from a color scanner.
, B (pull-), or the three color density signals Dr (red density), Dg (green density), and Db (blue density) obtained by logarithmically converting it, are converted into three quantities of color development system: hue, brightness, and saturation. 2. The color adjustment method according to claim 1, wherein the color adjustment method comprises a table. (3) The memory color adjustment unit consists of a saturation and hue table for specifying the 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 at the center of gravity of the color area that you want to reproduce as a memory color, and the amount of adjustment becomes smaller continuously as you move away from the center of gravity.
2. The color adjustment device according to claim 1, wherein the adjustment is performed using a saturation parameter. (4) The color developer system inverse conversion unit has three components: hue, brightness, and saturation.
Claim 1 comprising a table for converting the amount into three color density signals input to the masking unit.
Color adjustment method described. (5) The masking unit generates drive signals C (cyan), M (magenta), Y (yellow) or C, M, Y, K (
2. The color adjustment method according to claim 1, further comprising a table for generating a color (black).