JPH08191400A - Method and device for adjusting color of color image - Google Patents

Abstract

PURPOSE: To selectively and easily adjust the color contained in a color image as desired. CONSTITUTION: This device is composed by being provided with a reference color designator 16 storing the color image inputted by an image data input device 11 as the data of each picture element in an image data storage device 12, outputting the color of the picture element of the prescribed area of the color image displayed on a display 1 from an image data output device 28 after the color is adjusted to a target color and designating a reference color from the color images, a target color designator 18 designating the target color, a category discriminating part 23 determining the category based on the basic color name to which each picture element data belongs, an adjustment amount calculating part 26 calculating the adjustment amount for changing the reference color to the target color, a color adjustment arithmetic part 21 performing the color adjustment calculation of each picture element based on adjustment amount and color adjustment correction arithmetic part 22 correcting the color adjustment arithmetic result by defining the category to which the reference color determined by a category discriminating part 25 belongs as a reference for each picture element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image color adjusting method and apparatus, and more particularly to a color image color adjusting method and apparatus capable of easily and reliably adjusting a color of a color image to a target color.

[0002]

2. Description of the Related Art Conventionally, in an image editing apparatus for printing, for example, color correction of a color image is performed by first displaying a target image on a color display, and an operator watching the screen, cyan (C) which is a primary color of printing. , Magenta (M), yellow (Y), and black (K), the gradation conversion curves for the four color components are corrected.

That is, for example, when the original image is entirely purple, the operator changes the shape of each gradation conversion curve while considering the balance of each color component so as to correct it. The image converted by the gradation conversion curve is confirmed on the screen, and if necessary, further adjustment is performed.

[0004]

However, in the method of correcting the gradation conversion curve and adjusting the color as described above,
Since it is necessary to individually adjust the four color components of cyan, magenta, yellow, and black, which are the primary colors of printing, to change the colors, knowledge and skill on color mixing are required, and therefore use without knowledge of color mixing There is a problem that it is difficult for a person or an operator with little experience to operate, and it is difficult to obtain a satisfactory result in terms of quality.

Further, as a color tone correction of a color image, it is sometimes desired to change only a specific color range of the original image. In this case, the method of changing the shape of the gradation conversion curve as described above to change the balance of each color component also affects all other colors including the color component to be changed, so it is necessary to change it. There was a problem that even the uncolored colors would change.

To explain this in detail, for example, when the purple part is changed to red, purple is mainly represented by magenta and cyan components in printing. Need to be reduced and the yellow component increased instead. However, if the cyan component is reduced, the part that was initially cyan becomes lighter, and the color of the part that was blue is relatively magenta, so it changes to reddish blue, that is, purple, and similarly the yellow component. By increasing, the yellow color becomes stronger and the red color changes to orange. Therefore, in the above method,
There is a drawback in that it is not possible to change only a specific color range.

The present invention has been made to solve the above-mentioned conventional problems, and even a user who has no knowledge of color mixture or an operator who has little experience can easily obtain only necessary colors included in a color image by electronic means. It is an object of the present invention to provide a color image color adjusting method and device capable of selectively adjusting a desired color to a desired color.

[0008]

According to a first aspect of the present invention, image data is input, a color image is displayed on a display based on the image data, and each pixel in an adjustment target area included in the color image is displayed. In a color adjustment method of a color image in which image data is adjusted for each color, a representative point in an adjustment target area on a display is designated to specify a reference color to be a reference for adjustment, and the reference color is adjusted. Discriminates the category classified based on the basic color name to which the color belongs, specifies the target color as the adjustment target for the reference color in the same category as the reference color, and sets the color space coordinate value of each pixel in the adjustment target area. The problem is solved by adjusting the image data described in (1) in consideration of the reference color and the target color.

According to a second aspect of the present invention, the image data is input, a color image is displayed on the display based on the image data, and the image data is set for each pixel in the adjustment target area included in the color image. In the color image color adjusting method of adjusting the color by adjusting the color, a representative point in the adjustment target area on the display is designated to specify a reference color as a reference for adjustment, and the basic color to which the reference color belongs An image described by discriminating the categories classified based on the name, designating a target color as an adjustment target for the reference color in a category different from the reference color, and describing the color space coordinate value of each pixel in the adjustment target region. The problem is similarly solved by adjusting the data in consideration of the reference color and the target color.

According to the present invention, in the color adjusting method of a color image according to claim 1 or 2, the adjustment amount of the image data is obtained by subtracting the reference color data from the target color data, and the adjustment amount is obtained in the color space of each pixel. The adjustment amount is added to the coordinate value, and the adjustment amount is corrected if necessary.

According to the present invention, in the color adjustment method for a color image, the adjustment amount of the image data is added to the target color data by the adjustment amount obtained by subtracting the reference color data from the color space coordinate value of each pixel. The adjustment amount is corrected if necessary.

According to the present invention, in the color adjusting method for a color image, when the color space coordinate value of each pixel in the adjustment target area is adjusted based on the calculated adjustment amount, it is within the category to which the target color belongs. The adjustment amount is corrected so that it falls within the range.

According to the present invention, in the color image color adjusting method described above, a pixel included in a color region of a category to which a reference color belongs is selected and extracted as a region to be adjusted.

According to the present invention, the image data of the color image is input by the image data input means, the color image is stored in the image storage means as the data of each pixel, and is displayed on the display. In the color image color adjusting apparatus for adjusting the color of the predetermined area of the color image to the target color and outputting the adjusted image data by the image data output means, the color image can be adjusted from the color image displayed on the display. Reference color designating means for designating a reference color to be a reference, target color designating means for designating a target color to be a reference color adjustment target, and a basic color to which the image data of each pixel constituting the reference color and the color image belongs. The category discriminator that obtains the category classified based on the name, and the category that belongs to the same category as the category to which the reference color obtained by the category discriminator belongs Adjustment area extracting means for extracting a pixel having image data as an adjustment target area, and an adjustment amount for calculating the adjustment amount in consideration of the color space coordinate value of each pixel in the adjustment target area, the reference color and the target color. The calculation means, the color adjustment calculation means for performing color adjustment calculation for each pixel in the adjustment target area based on the adjustment amount obtained by the adjustment amount calculation means, and the color adjustment calculation means for each pixel in the adjustment target area, The problem is similarly solved by including a color adjustment correction calculation unit that corrects the color adjustment calculation result obtained by the color adjustment calculation unit on the basis of the category to which the target color belongs.

[0015]

The present inventors, even those who have no knowledge of color mixing,
As a result of various studies to develop a technology that allows an inexperienced operator to easily and surely adjust a desired color in a color image to a target color, as a result, the color of the pixel is determined from the image data of each pixel of the color image. Under the condition that human beings can easily recognize visually, by determining the category of the basic color name that belongs to, limiting the colors adjusted based on this category, and limiting the adjustment amount to an appropriate range, We have found that adjustment is possible. The present invention has been made based on this finding.

First, regarding the basic color name which is the feature of the present invention, "Optics", Vol. 17, No. 12, No. 6, issued in 1988.
Explaining the contents of "Category perception of surface color" published on pages 61 to 669, people generally classify colors into categorical categories by color name, and the colors are treated as if they were discrete quantities. It's handled. For example, a color referred to by one color name "green" includes many consecutive "greens" such as light green, dark green, green close to yellow, green close to blue, and the like. However, people have grouped these consecutive different colors into one "green" category and other "yellow" or "blue" categories.
It is distinguished from the category such as.

The existing and developed languages have a color category consisting of 11 basic color names, and the color space is divided into common categories according to these basic color names in every language. For example, in the case of Japanese, the basic color names forming the color category are 11 colors of white, black, red, green, yellow, blue, brown, purple, orange, pink, and gray.

The correspondence between the basic color name and the color space is obtained by the psychophysical experiment introduced in the above document, and the basic color name is uniquely associated with all colors in any color space. be able to.

Therefore, as in the first aspect of the present invention, the representative point in the adjustment target area is designated to specify the reference color as the reference for adjustment, and the category of the color to which the reference color belongs is determined. A target color that is an adjustment target for the reference color is specified in the same category, and the image data described by the color space coordinate value of each pixel in the adjustment target region is considered in consideration of the reference color and the target color. By adjusting, it becomes possible to use the categories classified by the above basic color names as an index or a reference when performing color correction, and only the necessary colors can be selectively and easily adjusted to the desired color. It becomes possible.

In the present invention, the color space coordinate values include L ^* C ^* H °, which will be described in detail later, and RG.
B, CMYK, uniform color space L ^* a ^* b ^* , L ^* u
A coordinate system value such as ^* v ^* can be adopted.

Next, the basic principle of the present invention will be described with reference to the flowchart of FIG. The target color image is a set of primary color signals in which the image data of each pixel is independent (usually an RGB signal for color display device display, or CMY for printing or color hard copy device output).
Or CMYK signals).

First, in step S1, a representative point where the color to be adjusted in the target image is displayed is designated, a color as a reference for adjustment, that is, a reference color is designated, and then in step S2, it becomes a target for adjustment. Specify a color, that is, a target color. afterwards,
In step S3, the image data of each pixel of the entire image is represented by an appropriate color space having independent coordinate axes corresponding to lightness, saturation, and hue (for example, a CIE1976L ^* a ^* b ^* uniform color space is represented by a cylindrical coordinate. (L ^* C ^* H ° color space). As a result, the color of each pixel of the original image can be operated independently for each of lightness, saturation, and hue.

Next, in step S4, the color category of each pixel is determined based on the category classification consisting of the above-mentioned 11 basic colors from white to gray in the color space. In the next step S5, only the area of the color belonging to the same category as the reference color designated in step S1 is extracted. In step S6, as the adjustment amount, for example, the amount necessary to change the reference color to the target color from the reference color specified in step S1 and the target color specified in step S2 (the difference between the two color data) is calculated. To do.

In step S7, for each pixel in the adjustment target area extracted in step S5, the adjusted color is calculated based on the adjustment amount calculated in step S6, and the category is calculated. Here, for example, as described in an example described later, it is determined whether the adjusted color category is the same as the target color category, and if different, the color of the same category as the target color is determined. Correct the adjustment amount so that When the image data of the adjusted image is obtained in this way, it is finally converted into image data of the same expression format as the original image in step S8, and the entire processing is completed.

As described above, in the present invention, the color of each pixel of the color image is made to correspond to the category of the basic color so that the area of the color to be adjusted and the adjustment amount can be appropriately controlled. It is possible to easily obtain the adjustment result that matches the perception. That is, it is possible to selectively adjust only the color of the category to be adjusted, and it is possible to prevent the color adjustment from changing the image to a color of a completely different category. It is also possible to adjust the colors of different categories as needed.

According to the second aspect of the present invention, the target color to be adjusted with respect to the reference color is designated by a category different from the reference color, and the image data described by the color space coordinate value of each pixel in the adjustment target area is specified. Is adjusted in consideration of the reference color and the target color. Therefore, even in the case of adjusting a color image to a color of a different category, the adjustment can be performed simply and accurately as in the invention of claim 1. it can.

According to the first or second aspect of the present invention, the adjustment amount of the image data is obtained by adding the adjustment amount obtained by subtracting the reference color data from the target color data to the color space coordinate value of each pixel, and if necessary, When the adjustment amount is corrected, the color adjustment based on the category can be appropriately performed.

In the invention of claim 1 or 2, the adjustment amount of the image data is added to the target color data by adding the adjustment amount obtained by subtracting the reference color data from the color space coordinate value of each pixel, and if necessary, the adjustment is performed. When the amount is corrected, similarly, it is possible to appropriately perform the color adjustment based on the category.

In the invention of claim 1 or 2, when the color space coordinate value of each pixel in the adjustment target area is adjusted based on the calculated adjustment amount, the adjustment amount is set so that it falls within the category to which the target color belongs. When the correction is performed, natural color adjustment can be performed on the entire adjustment target area.

In the invention of claim 1 or 2, when the pixels included in the area of the color of the category to which the reference color belongs is selected and extracted as the adjustment target area, the colors of the same category included in the entire image are extracted. It is possible to perform an appropriate color adjustment for.

According to the invention of claim 7, it is possible to surely carry out any of the inventions of claims 1 to 6.

[0032]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a block diagram showing a schematic structure of a color adjusting device according to the first embodiment of the present invention, and FIG. 3 is a schematic front view showing a color display (display device) included in the color adjusting device. Is.

The color adjustment of the color image for printing will be described below as an example. In the color display device 1 for displaying the target image to be subjected to the color adjustment shown in FIG. An image of a landscape showing a lake and clouds in the sky is displayed. Here, the target images for color adjustment are cyan (C), magenta (M), which are the primary colors for printing,
The landscape image is represented by yellow (Y) and black (K) data, and the landscape image is converted into R, G, B data by a method described later, and then the color display device 1 displays. It is displayed in the image display area 2.

In this embodiment, the color adjustment operation on the screen is executed by the following procedure. Reference numeral 3 shown in FIG.
Is an operation panel display area in which an operation panel for performing various operations necessary for color adjustment is displayed. In this display area 3, the reference color for color adjustment (the color of the representative point in the target image) is displayed. A reference color display area 4 for displaying and a target color display area 5 for displaying a target color for color adjustment are displayed in a rectangular frame. The target color displayed in the target color display area 5 is set by the target color adjustment bar 6, and the target color adjustment bar 6 has a hue adjustment bar 7 as shown in an enlarged view in FIG. It is composed of three bars, a lightness adjusting bar 8 and a saturation adjusting bar 9.

Next, various operations performed by the operator when adjusting the color of the printing color image while looking at the display screen of the display device 1 will be described in order.

(1) Designation of reference color The operator looks at the target image displayed in the image display area 2 and designates one point of the image including the color to be adjusted by the coordinate designating means such as a mouse. That is, if you move the cursor on the screen with the mouse and point the cursor at one point on the image, the color at that point is selected as the reference color to be adjusted, and the patch of the color specified on the screen is displayed in the reference color display area. Four
Is displayed in.

(2) Designation of target color By moving the position of the hue adjustment bar 7 constituting the target color adjustment bar 6 left and right, the display color of the target color display area 5 is changed from red to orange, yellow, green, blue, Continuously changing between all hues of purple, similarly moving only the brightness adjusting bar 8 to continuously change only the brightness, and moving the saturation adjusting bar 9 to continuously change only the saturation. It can be changed.

Therefore, the operator can specify the target color by moving the three kinds of operation bars 7 to 9 of the target color adjusting bar 6 to desired positions on the screen with a mouse or the like. The target color may be specified by inputting CMYK numerical data from the keyboard.
Alternatively, a color palette may be separately displayed on the screen, and a color may be selected from the color palette. Further, if the target color exists in the image on the display, it is also possible to adopt a method of designating one point and designating the color.

When the target color is determined in this way, the operator clicks the execution command instruction box 10 on the screen with a mouse or the like to start the process for color adjustment.

(3) Conversion of Color Signal In the color adjustment processing, first, the image data is set to lightness, saturation,
It is converted into L ^* , C ^* , and H ° data corresponding to the hue. Image data of c, m, y, k (cyan (C), magenta (M), yellow (Y), black (K) halftone dot area ratios (0 ≦ c, m, y, k, respectively) ≦ 1)
Represents the data from step 1
It is converted into L ^* , C ^* , and H ° color space data through the three-step processing of 3. (Step 1): Tristimulus values X, Y, from c, m, y, k
Calculate Z. (Step 2): Tristimulus values X, Y, Z to L ^* , a ^* ,
Calculate b ^* . (Step 3): C ^* and H ° are calculated from a ^* and b ^* .

The above step (step 1) is performed, for example, by the well-known Neugebauer equation represented by the following equation (1).

X = X p (1-c) (1-m) (1-y) (1-k) + X _C c (1-m) (1-y) (1-k) + X _M (1-c ) M (1-y) (1-k) + X _Y (1-c) (1-m) y (1-k) + X _K (1-c) (1-m) (1-y) k + X _CM cm (1-y) (1-k) + _XCYc (1-m) y (1-k) + _XCKc (1-m) (1-y) k + _XMY (1-c) my ( 1-k) + X _MK (1-c) m (1-y) k + X _YK (1-c) (1-m) y k + X _{CMY cmy} (1-k) + X _CMK cm (1-y) _{) k + X CYK c (1} -m) y k + X MYK (1-c) m y k + X CMYK c m y k ... (1)

The above equation (1) in Xp are tristimulus values of the printing _{paper, X C, X M, X} Y, C is X _K indicated in each subscript, M, Y, a monochromatic Each ink K Tristimulus values of the solid part printed, similarly X _CM , X _CY , X _CK , X _MY , X
_MK , X _YK are tristimulus values when two colors are overprinted, X _CMY ,
X _CMK , X _CYK , and X _MYK are tristimulus values when three colors are overprinted, and X _CMYK are tristimulus values when four colors are overprinted.

As described above, the tristimulus value X is calculated by the above equation (1), but the other two tristimulus values Y and Z are the same as those in which X in this equation (1) is replaced with Y and Z, respectively. It can be calculated by the formula.

Although the Neugebauer equation is used here, the color patch of the combination of c, m, y and k is measured to form a look-up table, and XYZ is directly converted from cmyk based on this table. You may ask.

In the next (step 2), the values of L ^* , a ^* and b ^* are calculated by the following equation (2).

L ^* = 116 (Y / Y0) ¹ / 3-16 (when Y / Y0> 0.008856) L ^* = 903.25Y / Y0 (when Y / Y0 ≦ 0.008856) a ^* = 500 {(X / X0) ¹ / 3- (Y / Y0) ^1/3 } b ^* = 200 {(Y / Y0) ¹ / 3- (Z / Z0) ^1/3 } (X0, Y0, Z0 are Tristimulus value of reference white surface) (2)

When using the above equation (2), X0,
The tristimulus values of the reference white surface of Y0 and Z0 can be obtained by corresponding to the values of X, Y, and Z of the perfect diffusion antislope such as barium sulfate.

Further, in (step 3), the values of C ^* and H ° are calculated by the following equation (3).

C ^* = {(a ^{* 2} + b ^{* 2} )} ^1/2 H ° = tan ⁻¹ (b ^* / a ^* ) (3)

As described above, c, m, y, k of each pixel
Data is converted into data (coordinate values) in the color space coordinate system in the expression format of L ^* , C ^* , and H °. After converting the c, y, m, and k data into L ^* , C ^* , and H ° data in this way, in order to obtain the category of the basic color to which the color belongs, the category discrimination described in (4) below is performed. I do.

(4) Category Discrimination This category discrimination processing is performed using a category number table (lookup table) as shown in FIG. That is, in this category number table, for the combination of the values of L ^* , C ^* , and H °, the above 1
Data representing the categories corresponding to the basic color name of one color by numbers from 1 to 11 is preset, and L ^* ,
The corresponding category number N can be searched using the values of C ^* and H ° as indexes.

This category number table may be provided with category number data for all possible combinations of L ^* , C ^* , and H ° values, but L ^* , C
The values of ^* and H ° are not necessarily integers, and the number of data is very large, which is not realistic. Therefore, the category number data is given only to the representative color represented by the combination of the values of L ^* , C ^* , and H ° sampled at appropriate intervals (for example, an integer value in increments of 1) to form a table. For other colors, the category number is determined by judging from the representative colors around. In particular,
For colors other than the representative color, the category number of the representative color having the shortest Euclidean distance in the three-dimensional space of L ^* C ^* H ° may be used as the category number of the color.

If the representative color is set by setting the sampling interval in the L ^* C ^* H ° space to be sufficiently small, the estimation accuracy of the category number with respect to an arbitrary color will not be a practical problem. In this way, all the pixels are associated with one of the 11 category numbers.

Although the category number table for L ^* , C ^* , and H ° is adopted in this embodiment, since the category classification by the basic color is possible in any color space, L ^* a ^* b ^*. The category number table may be configured for the CMYK color space. However, in this case, the processing content described later changes slightly.

(5) Extraction of Adjustment Target Area First, the category number to which the reference color belongs is determined by applying the discrimination method described in (4) above to the reference color designated previously. Next, pixels of a color having the same category number as the category number of the reference color are extracted from the entire image as an adjustment target area. Color adjustment is performed only on the pixels thus extracted. Therefore, if, for example, blue is designated at the stage of designating the reference color, all pixel portions of the blue category are picked up as adjustment target regions regardless of the two-dimensional location on the screen. If the adjustment target area (the category of the adjustment target color) is not limited and all the colors forming the image are desired to be adjusted, this extraction step may be skipped.

The extraction of the adjustment target area is not limited to the extraction based on the area of the color space corresponding to the category as described above, but the range of the two-dimensional area on the screen is designated and the area is adjusted. It also includes a process of extracting the adjustment target.

(6) Calculation of adjustment amount For the reference color and the target color designated previously, the change of (3)
L by conversion processing^*, C^*, H ° value is calculated,
Standard color C_srcThe calculation result for L_src ^*, C _src ^*,
H_srcAnd the target color C_desAgainst L_des ^*, C_des
^*, H_desIf °, the standard color C_srcThe target color C_desTo
Adjustment amount necessary to change ΔL^*, ΔC^*, ΔH ° is
It is calculated by the following equation (4).

[0060] ^{_{ΔL * = L des * -L src}} * ΔC * = C des * -C src * ΔH ° = H des ° -H src ° ... (4)

Next, the adjustment amounts ΔL ^* , ΔC ^* , ΔH °.
By using the color space coordinate values L1 ^* , C1 of each pixel before adjustment
Colors L2 ^* , C2 ^* , H2 ° after adjustment for ^* , H1 °
Is calculated by the following equation (5).

L2 ^* = L1 ^* + ΔL ^* C2 ^* = C1 ^* + ΔC ^* H2 ° = H1 ° + ΔH ° (5)

(7) Correction of adjustment amount With respect to the color after adjustment calculated by the above equation (5), the category number is determined from the values of the color space coordinates L ^* , C ^* , and H ° as described in (4) above. The category number obtained by the processing is compared with the category number of the color before adjustment to determine whether or not the category number is changed by the adjustment according to the equation (5). Based on the determination result, the adjustment amount is corrected. Is done.

The adjusting condition may be changed to a color in the same category as the original color or may be changed to a color in a category different from the original color. In the latter case, it is not necessary to correct the adjustment amount, but in the former case, for example, the following correction process is performed.

When there is no pixel whose category is changed before and after the adjustment calculation by the equation (5), L2 ^* , C2 ^* , H2 calculated by the equation (5) is directly calculated.
Let ° be the adjusted color.

On the contrary, when there is a pixel whose category changes before and after the adjustment, the adjustment amount is corrected so that the category does not change only for the corresponding pixel. Various methods can be considered for this correction, and one example thereof will be described below.

First, the adjustment amount ΔL obtained from the above equation (5)
^{Based on *} , ΔC ^* , ΔH °, the correction amounts Δl ^* , Δc ^* , Δ
h ° is calculated by the following equation (6).

Δl ^* = ΔL ^* / n Δc ^* = ΔC ^* / n Δh ° = ΔH ° / n (6)

Here, n is an appropriate positive integer value, and can be set to a value of about 10, for example.

Next, the data L3 ^* , C3 ^* , H3 ° after the adjustment amount correction are calculated by the following equation (7).

L3 ^* = L2 ^* −Δl ^* C3 ^* = C2 ^* −Δc ^* H3 ° = H2 ° −Δh ° (7)

L3 ^* , C3 ^* , and H3 ° thus obtained
Apply the above discrimination method to obtain the category number,
The category number is again compared with the category number before adjustment, and if the category number is the same, the result of the equation (7) is adopted. If the category numbers are still different, L
By substituting the calculation results of 3 ^* , C3 ^* , and H3 ° into L2 ^* , C2 ^* , and H2 ° of the above formula (7), new values of L3 ^* , C3 ^* , and H3 ° are obtained by the formula (7). Is calculated to obtain the category number and similarly compared with the category number before adjustment. The process of this procedure is repeated until the same category number as before adjustment is obtained.

In the above equation (7), L ^* , C ^* , H °
The case where the adjustment amount is corrected for each of the three coordinate values is shown.
You may correct one or two. Further, if it is desired to approach the target adjustment amount as close as possible, the value of n in the equation (6) should be set as large as possible to reduce the correction amount. However, it should be noted that if the value of n is set too large, the number of times of repetitive calculations will increase and the processing time will increase.

(8) Inverse conversion of color signal By the processing up to (7) above, adjustment by the data of L ^* , C ^* , and H ° is completed, and the color space coordinate value to be set for each target pixel is decided. Therefore, the coordinate values (L ^* , C ^* , H °) of the finally determined pixels are inversely converted into C, M, Y, K data having the same expression format as the original image. This inverse conversion is achieved by performing the reverse processing from the expression (3) to the expression (1), which is opposite to the conversion processing from the expression (1) to the expression (3).

Next, a color adjusting apparatus of this embodiment capable of executing the processes (1) to (8) will be described with reference to the block diagram shown in FIG.

The image data input device 11 reads a color original and prints halftone dot area ratio data (c, m, y,
For inputting k), a specific means may be, for example, a plate-making scanner or the like. In addition to this, it is a device that takes in printing data created by another plate making system by using an offline data input device such as a magnetic tape device or a magneto-optical disk device, or an online data input means. May be.

The image data storage device 12 uses the image data input from the image input device 11 and the color adjustment device of the present embodiment to carry out the processes (1) to (8) described above to perform a color signal inverse conversion unit, which will be described later. Image data input from 27 is stored,
For example, it is composed of a magnetic disk device for storing. The image data input device 1 is stored in the image data storage device 12.
After the image data is input from 1, the input image data is read from the image data storage device 12 for each pixel,
It is adapted to be sent to the color signal conversion unit 13.

The color signal converting section 13 is composed of the equations (1) to
Halftone dot area ratio data (c, m, y, k) is calculated by the equation (3)
Is converted into a color signal suitable for subsequent processing. Further, the color signal conversion unit 13 has a function of converting the input image data of each pixel into tristimulus values (X, Y, Z) by the equation (1) and outputting the result to the XYZ → RGB conversion unit 14. I also have. The conversion unit 14 converts the input data into RGB data for display on the display, and then outputs the RGB data to the display memory 15, which further outputs the RGB data to the color display device 1 shown in FIG. However, the color image to be adjusted is displayed.

The reference color designating device 16 is used to designate the coordinates of a place to be adjusted on the image displayed in the image display area 2 of the display device 1 shown in FIG. A mouse or the like to be connected.

Points specified by the reference color specifying device 16
Pixel data of (c_src, M_src, Y _src, K_src) Is the base
The reference color display image of FIG.
The patch of that color is displayed on the rear 4.

The target color designation device 18 displays in the target color display area 5 by operating the target color adjustment bar 6 displayed in the operation panel display area 3 of the color display device 1 of FIG. 2 with a mouse or the like. The target color to be
You can set it while changing it for each saturation and brightness, or directly
It has a function to specify a color with numerical data. Image data of a target color can be input by the target color designation device 18, and this data is stored in the target color data storage unit 19 as color space coordinate values (L
_des ^* , _Cdes ^* , _Hdes °).

Stored in the reference color data storage unit 17
The reference color data is processed by the color signal conversion unit 13 for the lightness, saturation, and hue.
L corresponding to^*, C^*, H ° value (L_src ^*,
C_src ^*, H _src°) and the converted data is
It is output to the 1-category discrimination unit 23 and the adjustment amount calculation unit 26.
It

The first category discriminating section 23 has a function of calculating the category number from the coordinate values of L ^* , C ^* , and H ° input from the color signal converting section 13 and the target color data storing section 19, respectively. Then, each pixel data of the image, the reference color data and the target color data are processed here. The category number data N _src of the reference color and the category number data N _des of the target color discriminated by the first category discriminating unit 23 are input and stored in the category number storage unit 24.

Further, the adjustment amount calculating section 26 is arranged so that the reference color data (L _src ^* , C _src) inputted from the color signal converting section 13 is inputted.
^* , H _src °) and the target color data (L _des ^* , C _des ^* , H _des °) stored in the target color data storage unit 19 are necessary for the color adjustment used in the equation (5). L ^* C ^*
The adjustment amount (ΔL ^* , ΔC ^* , ΔH °) in the H ° space is calculated.

The adjustment area extraction unit 20 receives the category number data N input from the first category discrimination unit 23 for each pixel.
And the category number data N _src of the reference color stored in the category number storage unit 24 are compared, and if the two are the same, the pixel data (L1 ^* , C1 ^* , H1 °) is sent to the color adjustment calculation unit 21. Output. On the contrary, if they are different, the pixel data is output to the color signal inverse conversion unit 27 after passing through the process in the middle. As a result, only the pixels having the same category number as the reference color in the entire image, that is, the pixels existing in the predetermined area in the color space, are selected (extracted) as the adjustment target area, and only the extracted specific pixels are colored. Adjustments can be made.

In the color adjustment calculation unit 21, the adjustment amount (ΔL ^* , ΔC ^* , ΔH °) calculated by the adjustment amount calculation unit 26.
On the basis of the above, the calculation of the color adjustment using the equation (5) is executed for each pixel selected and input by the adjustment area extracting unit 20. The resulting color space coordinate values (L2 ^* , C2 ^* , H2 °) for each pixel are input to the second category discriminating unit 25, where the categories are discriminated as in the case of the first category discriminating unit 23. The category number N '
Is obtained and is output to the color adjustment correction calculation unit 22.

In this color adjustment correction calculation section 22, the inputted category number _N'is compared with the category number N _des of the target color stored in the category number storage section 24. For example, in the item (7) above. The correction calculation processing of the color adjustment amount described above is executed, and the necessary correction calculation of the color adjustment amount is executed.

As a result, the corrected color space coordinate values (L3 ^* , C3 ^* , H3) obtained as the value on the left side of the equation (7) are obtained.
.Degree.) Is output to the color signal inverse conversion unit 27 and is returned to the halftone dot area ratio data (c ', m', y ', k') together with the pixel data not selected by the adjustment area extraction unit 20. The final result of the color adjustment is stored in the image data storage device 12 and is read out by the image data output device 28 as necessary, and is output as image data adjusted by the method of this embodiment. It is supposed to do. As the image data output device 28, normally,
A plate making scanner or the like that can output to a color separation film is used, but a data exchange device that can be passed as image data to another system may be used.

Next, the operation of this embodiment will be described with reference to the flow charts of FIGS.

When image data is input from the image data input device 11, the color signal conversion unit 13 performs color signal conversion on the data (step S11), and the converted color space coordinate values L1 ^* , C1. The category is discriminated by the first category discriminating unit 23 for ^* and H1 ° (step S1).
2), the category number N is calculated, and XYZ
→ It is output to the display device via the RGB conversion unit 14 and the display memory 15, and a color image is displayed on the display.

On the other hand, the reference color designating device 16 designates a reference color on the screen, and the data thereof is similarly processed by the color signal converting unit 13.
The color signal conversion is performed in step S13, and the first color discriminating unit 23 discriminates the color space coordinate values L _src ^* , C _src ^* , and H _src ° after the conversion to obtain the category number N _src. Then, the category number is compared with the category number N obtained for each pixel in step S12 (step S15).

Further, the target color is designated by the target color designating device 18, and the adjustment amount calculator 26 converts the color space coordinate values L _des ^* , C _des ^* , H _des ° of the target color into the above-mentioned step S12. Color space coordinate value L of the standard color obtained by
_The adjustment amounts ΔL ^* , ΔC ^* , and ΔH ° are calculated from _src ^* , C _src ^* , and H _src ° according to the equation (4) (step S1).
6) Further, the color adjustment correction calculator 22 calculates the correction amount according to the equation (6) (step S17).

Then, in step S15, the same color as the reference color is obtained.
Of the pixels in the image data determined to be in one category
Adjustment for color space coordinate values calculated in step S16
The equation (5) is calculated using the amount (step S1
8), coordinate value L2 after the calculation ^*, C2^*, H2 °
Then, the second category determination unit 25 determines (step S1
9), the category number N ′ is the category number of the standard color
Issue N_src(Step S20) and N '≠ N_srcof
In this case, in the color adjustment correction calculation unit 22,
Correction calculation is performed (step S21), and the coordinate value L
Three^*, C3^*, H3 ° is performed again for category determination
(Step S22), with the category number N ″ at that time
Standard color category number N_srcAnd compare again and again
(Step S23), N ″ ≠ N_srcIf the above, (7)
L2 on the right side of the expression^*, C2^*, H2 ° is the coordinate value
L3^*, C3^*, H3 ° to replace the adjustment data
Do (step S24), and categorize at step S23.
Repeat steps S21 to S24 until the renumbers match.
Repeat.

Further, N ≠ N _{src in} step S15, N ′ = N _{src in} step S20 or N ″ in step S23.
= N _src, the color signal inverse conversion unit 27 performs inverse conversion of the image data for each color space coordinate value (step S25), and the final color adjusted data (c ′,
m ', y', k ') (step S26), which is stored in the image data storage device 12 and, if necessary, output from the image data output device 28.

Further, the tristimulus values X ', Y', Z'in the middle obtained by the inverse conversion of the step S25 are converted into R, G, B signals, and the color-adjusted color image is displayed on the display ( Step S27).

According to the present embodiment described above, the color of each pixel of the color image is classified based on the category classification based on the basic color name. Therefore, by specifying the category of the color to be adjusted, the image is adjusted. It is possible to extract the area of the color belonging to the category from. Since this category classification is based on human vision, extraction results that match the vision can be obtained. In addition, we made it possible to perform color adjustment so that the color category does not change even after adjustment, so it is necessary to make color adjustments that change the color so much that it is perceived as a color of another category. Can be prevented. Further, by introducing the concept of the category based on the basic color name, it becomes easy to predict the effect of color adjustment, so that even a person who has no knowledge of color mixing can easily perform the operation of color adjustment.

Next, a color adjusting apparatus according to the second embodiment of the present invention will be described.

The color adjusting apparatus according to the present embodiment is designed such that the image displayed in the image display area (display) 2 of the display device 1 is predetermined with respect to the two-dimensional image displayed in the XY coordinate system by the mouse. When the area range is specified and the area range is extracted as the color adjustment target area and the target color for the reference color is specified in different categories, the image data of each pixel in the adjustment target area is set as the target color. The color adjusting apparatus is substantially the same as the color adjusting apparatus of the first embodiment except for the method of calculating the correction amount necessary for changing to the color of the same category. That is, the color adjusting device of the present embodiment is
For example, the adjustment area extraction unit 20 shown in FIG.
This can be realized by providing a function of extracting a three-dimensional area and having a function of correcting the color (image data) of each pixel in the adjustment target area to a color of the same category as the target color by the color adjustment correction calculation unit 22.

In this embodiment, for example, a mouse is used for empty 2
The lowest position of A is designated, the two-dimensional range above it is extracted as an adjustment region, and an empty representative point is designated as in the case of the first embodiment, and its blue color is designated as the reference color. By doing so, only the image of the blue sky can be specified as the adjustment target. Therefore, Lake 2 on the hillside
Even if B is blue in the same category, the color of the lake can be excluded from the adjustment target.

Further, in this embodiment, it is possible to designate a target color, for example, a red color having a different category from the color to be adjusted. At this time, all the color space coordinate values (image data) of each pixel (included in the adjustment target area) that configures the image together with the color space coordinate values of the reference color existing in the adjustment target sky image are set as the target color. Can be converted to the same category. As a concrete method, first, as in the first embodiment, steps S11 to S11 of the flowchart of FIG.
After obtaining the adjusted colors L2 ^* , C2 ^* , H2 ° according to S18, as shown in FIG. 9 instead of FIG. 7, the category of this adjusted color is discriminated (step S19 ′), and the category is the target. There is a method of judging whether or not the color is in the same category as the color (step S20 '), and if the color is different from the target color, the color is corrected to the same category as the target color as follows.

First, the difference between the color space coordinate values L1 ^* , C1 ^* , H1 ° of each pixel included in the adjustment target area and the reference colors L _src ^* , C _src ^* , H _src ° before the adjustment (new Adjustment amounts) ΔLr ^* , ΔCr ^* , and ΔHr ° are calculated by the following equation (8).

[0102] _{^{ΔLr * = L1 * -L src *}} ΔCr * = C1 * -C src * ΔHr ° = H1 ° -H src ° ... (8)

Further, the following equation (9) is obtained from the above equations (4) and (5).

[0104] _{^{L2 * = L1 * + L des}} * -L src * C2 * = C1 * + C des * -C src * H2 ° = H1 ° + H des ° -H src ° ... (9)

Then, the following equation is obtained from the equations (8) and (9).

[0106] _{^{L2 * = L des * + ΔLr}} * C2 * = C des * + ΔCr * H2 ° = H des ° + ΔHr ° ... (10)

From the equation (10), the adjusted color L2^*, C2
^*, H2 ° is the target color L_des ^*, C _des ^*, H_des° and
Adjustment amount ΔLr^*, ΔCr^*, ΔHr °
I understand. Therefore, the color after adjustment is the same as the target color.
To correct the color so that
Adjusted amount ΔLr^*, ΔCr^*, ΔHr ° effect is corrected
do it.

Therefore, first, the adjusted colors L2 ^* , C2 ^* ,
Correction amount Δl calculated from H2 ° by the following equation (11)
r ^* , Δcr ^* , and Δhr ° are calculated (step S1)
7 '). Here, m is an appropriate positive integer value, and can be set to about 10, for example.

[0109] ^{Δlr * = ΔLr * / m =} (L1 * -L src *) / m Δcr * = ΔCr * / m = (C1 * -C src *) / m Δhr ° = ΔHr ° / m = (H1 ° -H _src °) / m (11)

Then, according to equations (10) and (11),
The corrected colors L4 ^* , C4 ^* , H4 ° are obtained by the following equation (12) (step S21 ').

L4 ^* = L2 ^* −Δlr ^* C4 ^* = C2 ^* −Δcr ^* H4 ° = H2 ° −ΔHr ° (12)

Next, the corrected colors L4 ^* , C4 ^* , H
The category of 4 ° is checked (step S22 '), and if it is the same as the target color, that value is adopted as the final correction value (step S23'). If the category is different from the target color here, L calculated by equation (12) is used.
The values of 4 ^* , C4 ^* , and H4 ° are substituted into L2 ^* , C2 ^* , and H2 ° (step S24 '), the process returns to step S21', the formula (12) is calculated again, and the resulting color is obtained. The category of is analyzed again to see if it is the same as the category of the target color. The processing of steps S21 'to S24' is repeated until the correction result becomes a color in the same category as the target color.

As described above, after the processing according to the flowchart shown in FIG. 9, L3 ^* , C3 ^* , and H3 ° are changed to L4 ^* , C in step S25 of the flowchart shown in FIG.
By replacing 4 ^* and H4 °, color adjustment can be performed in the same manner as in the case of the first embodiment according to the same processing procedure.

Therefore, according to the present embodiment, by designating the target color as red as described above, the lake 2 is included in the landscape image displayed on the display device 1 of FIG.
The blue color of B is left as it is, and only the color of the sky 2A is adjusted from blue color to red color at sunset, and the color adjustment between different categories is suitable for human vision as in the first embodiment. Since it can be performed under conditions, even an inexperienced operator or the like can easily and appropriately perform color adjustment.

The adjustment amount of the second embodiment is (1)
Color space coordinate value L1 of each pixel as given by equation (1)
^*, C1^*, H1 ° and standard color L_src ^*, C_src ^*, H
_srcIt is different from the first embodiment in that it is based on the difference from °.
ing. In addition, in the second embodiment, step S in FIG.
By performing the processing from 21 'to S24', the above (1
As a result, the value of the second item of each expression of 0) approaches 0.
Then, L2 after adjustment^*, C2 ^*, H2 ° is the target color
L_des ^*, C_des ^*, H_desTo approach °,
If the target color category is different from the standard color category
However, even if the
It will be adjusted to belong to the category. Follow
Other pixels to be adjusted that belong to the same category as the reference color
The color of the reference color to adjust the length of the difference vector
Can be corrected to a color in the same category as the target color by
become. This method can also be applied to the first embodiment.

The present invention has been specifically described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

For example, when the color adjustment is performed within the same category as the target color, a category check function for checking whether or not the color is out of the category as a result of the color adjustment calculation may be added.

The specific structure of the color adjusting device is not limited to that shown in the above embodiment.

[0119]

As described above, according to the invention of claim 1, even a user who has no knowledge of color mixture or an operator who has little experience can easily select only the necessary colors included in a color image by electronic means. The color can be adjusted to the desired color.

According to the second aspect of the invention, even when the colors of the target image and the target color are different, the target image can be adjusted to the target color in the same manner.

According to the invention of claim 3, it is possible to perform an appropriate color adjustment based on the category.

According to the fourth aspect of the invention, similarly, appropriate color adjustment can be performed based on the category.

According to the fifth aspect of the invention, it is possible to surely perform adjustment to a color that does not cause a feeling of strangeness.

According to the sixth aspect of the present invention, it is possible to appropriately adjust the colors of the same category existing at arbitrary positions in the entire image.

According to the invention of claim 7, it is possible to provide a color adjusting apparatus which can execute the color adjusting method according to the present invention.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining the basic principle of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a color adjusting apparatus of a first embodiment according to the invention.

FIG. 3 is an explanatory diagram showing a schematic configuration of a display device included in the color adjustment device.

FIG. 4 is an explanatory view showing an enlarged target color adjustment bar included in the display device.

FIG. 5 is an explanatory diagram showing an example of the configuration of a category number table.

FIG. 6 is a flowchart illustrating the operation of the first embodiment.

FIG. 7 is another flowchart for explaining the operation of the first embodiment.

FIG. 8 is still another flowchart for explaining the operation of the first embodiment.

FIG. 9 is a flowchart for explaining the operation of the second embodiment.

[Explanation of symbols]

 1 ... Color display device 2 ... Image display area 3 ... Operation panel display area 4 ... Standard color display area 5 ... Target color display area 6 ... Target color adjusting bar 7 ... Hue adjusting bar 8 ... Brightness adjusting bar 9 ... Saturation adjusting bar 10 ... Execution command command box 11 ... Image data input device 12 ... Image data storage device 13 ... Color signal conversion unit 14 ... XYZ → RGB conversion unit 15 ... Display memory 16 ... Reference color designation device 17 ... Reference color data storage unit 18 Target color designation device 19 Target color data storage unit 20 Adjustment region extraction unit 21 Color adjustment calculation unit 22 Color adjustment correction calculation unit 23 First category determination unit 24 Category number storage unit 25 Second category determination Part 26 ... Adjustment amount calculation part 27 ... Color signal inverse conversion part 28 ... Image data output device

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04N 1/46 Z

Claims (7)

[Claims] 1. Color image adjustment by inputting image data, displaying a color image on a display based on the image data, and adjusting the image data for each pixel in an adjustment target area included in the color image. In the color adjusting method of a color image, the representative point in the adjustment target area on the display is designated to specify the reference color as the reference for adjustment, and the color is classified based on the basic color name to which the reference color belongs. The category is discriminated, the target color to be the adjustment target for the reference color is specified in the same category as the reference color, and the image data described by the color space coordinate value of each pixel in the adjustment target area is used as the reference color. And a color adjusting method for a color image, which is adjusted in consideration of the target color. 2. A color adjustment is performed by inputting image data, displaying a color image on a display based on the image data, and adjusting the image data for each pixel in an adjustment target area included in the color image. In the color adjusting method of a color image, the representative point in the adjustment target area on the display is designated to specify the reference color as the reference for adjustment, and the color is classified based on the basic color name to which the reference color belongs. The category is discriminated, the target color as the adjustment target for the reference color is specified in a category different from the reference color, and the image data described by the color space coordinate values of each pixel in the adjustment target area is set to the reference color and A color adjusting method for a color image, wherein the target color is adjusted in consideration. 3. The adjustment of image data according to claim 1, wherein an adjustment amount obtained by subtracting the reference color data from the target color data is added to the color space coordinate value of each pixel, and if necessary, the adjustment is performed. A color adjustment method for a color image, which is performed by correcting an adjustment amount. 4. The adjustment of image data according to claim 1, wherein the adjustment amount obtained by subtracting the reference color data from the color space coordinate value of each pixel is added to the target color data, and the adjustment is performed as necessary. A color adjustment method for a color image, which is performed by correcting an adjustment amount. 5. The adjustment amount according to claim 1, when the color space coordinate value of each pixel in the adjustment target area is adjusted based on the calculated adjustment amount, the adjustment amount is set to fall within the category to which the target color belongs. A color adjustment method for a color image, which comprises: 6. The color adjusting method for a color image according to claim 1, wherein a pixel included in an area of a color of a category to which the reference color belongs is selected and extracted as the area to be adjusted. 7. Image data of a color image is input by an image data input means, the color image is stored in the image storage means as data of each pixel and is displayed on a display, and the color image of the color image displayed on the display is displayed. In a color image color adjusting apparatus that adjusts the color of a predetermined area to a target color and then outputs the adjusted image data by the image data output means, a reference that is a reference for color adjustment from the color image displayed on the display. Based on the basic color name to which the reference color specifying means for specifying the color, the target color specifying means for specifying the target color to be the reference color adjustment target, and the reference color and the image data of each pixel forming the color image belong The category discriminator for obtaining the classified category and the image data belonging to the same category as the category to which the reference color obtained by the category discriminator belongs Area extracting means for extracting a pixel having a pixel as an adjustment target area, and an adjustment amount calculating means for calculating an adjustment amount in consideration of the color space coordinate value of each pixel in the adjustment target area, the reference color and the target color. A color adjustment calculation means for performing color adjustment calculation for each pixel in the adjustment target area based on the adjustment amount obtained by the adjustment amount calculation means; and for each pixel in the adjustment target area, the target color A color adjustment device for a color image, comprising: a color adjustment correction calculation unit that corrects a color adjustment calculation result obtained by the color adjustment calculation unit on the basis of a category to which the color adjustment calculation unit belongs.