JPS61289386A - Contrast conversion control system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] When converting the gradation of a multi-gradation color image such as a full-color natural image, the specific color area specified by the image creator must be converted to the color of that area or the artificial color. For a color image area other than the specific color area, which is displayed in a composite color, a predetermined number of specified colors representing the area are automatically determined, and the gradation of the area is automatically converted using these specified colors. Thereby, it is possible to efficiently perform gradation conversion of a color image while suitably reflecting the intention of the image creator.

[Industrial application field]

The present invention relates to a gradation conversion control method for converting a multi-gradation color image such as a full-color natural image into a color image having an arbitrarily specified number of color gradations smaller than the number of color gradations.

[Conventional technology]

A multi-gradation color image such as a full-color natural image output from a video camera or a video tape has a huge number of color gradations, such as zza color.

On the other hand, in color image processing systems, the number of color gradations is small (
For example, it is often limited to 16 to 256 colors.

In this way, as a gradation conversion control method for converting a color image with an extremely large number of gradations into a color image with a small number of gradations, the conventional method was to: dividing the black and white image into image parts corresponding to specific regions or specific brightness level ranges;
A method in which the image creator selects the display color for each image part from among the specified colors and artificially synthesizes a color image close to the input color image. ■ A method in which a multi-gradation color image is input using a color television, camera, etc. , a method of automatically performing gradation conversion to obtain a color image close to the original input color image within a predetermined number of colors has been used.

[Problem that the invention seeks to solve]

In conventional gradation conversion control methods, method (■) is difficult to artificially express natural colors with a small number of specified colors;
Furthermore, since the image creator must input each area and the specified color for each area, there is a problem in that it is time-consuming. On the other hand, in the method (2), since the color is automatically determined, even if it is desired to arrange a desired specific color for a specific area, this is not possible.

[Means for solving problems]

The means taken by the present invention to solve the above-mentioned problems in the conventional gradation conversion control system will be explained with reference to FIG.

FIG. 1 is a block diagram showing the configuration of the present invention.

In FIG. 1, reference numeral 11O denotes a specific color area extracting means, which extracts at least one specific color from the color image area.
Extract specific color areas. The specific color area is manually specified by the image creator. The specific color is a color within a specific color area or an artificially synthesized color, and is arbitrarily specified by the image creator.

Reference numeral 120 denotes designated color determining means that automatically determines a predetermined number of designated colors representative of a color image area other than the specific color area.

Reference numeral 130 denotes a specific color input means for inputting each specific color for each specific color area.

Reference numeral 140 denotes a gradation conversion means, which automatically determines an area to be displayed with each specified color determined by the specified color determination means 120 for areas other than the specific color area, and for each specific color area, Each specific color input from the input means 130 is input.

[For production]

The operation of the present invention having the configuration shown in FIG. 1 will be explained with reference to FIG. 2. FIG. 2 is an explanatory diagram of an input color image of the present invention.

In the input color image 200 in FIG. 2, 210 is empty;
221-223 are clouds, 230 is the sea, 240 is a sandy beach, 25
1 is a leaf, 252 is a tree trunk, 260 is a person, 270 is an island, 280 is a yacht, and 29 is a ship.

Now, assume that the multi-tone color image 200 is toned-converted into a color image with fewer colors.

The image creator manually specifies specific areas to be displayed in r specific colors (k>r≧1) from among the multi-tone color image area using the specific color area extracting means 110.

A specific color area can be extracted by specifying a specific color from among the colors of the color image 200 as a point or area and extracting an area of these colors simultaneously, or by specifying a specific area. 'J
This is done by tJ.

For example, in FIG. 2, the number of designated colors is -16, the number of specific colors r=4, and among these four specific colors, sky 210. sea 23
0 and the sandy beach 240, the colors in each area are used, and artificial green is specified as the color of the tree leaves 251. In this case, when each pixel in each region of the sky 210, the sea 230, and the sandy beach 240 is the same, each region 2
By specifying any one point within 10 degrees 230 and 240, each 5Ivi of the sky 210, the sea 230, and the sandy beach 240 is specified as an area having that color. If, for example, the color of the sky 210 is not a single color, and you cannot specify the color of that area by simply specifying one point, specify an arbitrary closed area 211 in the sky 210, and select the closed area. The color of the sky 210 is specified by the color 211.

The closed area of the tree leaf 251 for which artificial green is specified is specified.

The specified color determining means 120 determines, for areas other than the specific color area, a predetermined number representing the SN area, that is, -r(-1
2) Automatically determine a designated color.

This method of automatically determining the specified color can be performed using various known methods.

The specific color input means 130 inputs each specific color for each specific color area.

For areas other than the specific color area, the 111UR conversion means 140 automatically determines areas to be displayed with each specified color determined by the specified color determination means 120. For each specific color area, each specific color input from the specific color input means is input.

As described above, the specific area specified by the image creator can be displayed in an artificial specific color or a specific color in a color image as desired by the image creator, and other areas can be displayed in each color. The gradation can be automatically converted and displayed using a color that represents the area.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 2 to 5.

FIG. 3 is a block diagram illustrating the configuration of an embodiment of the present invention, FIG. 4 is a diagram illustrating a color lookup table used in the embodiment, and FIG. 5 is a clustering method used in the embodiment. It is an explanatory diagram.

(Description of Configuration) In FIG.
40 is as explained in FIG.

150 is a television camera that outputs full-color natural image information. Reference numeral 160 denotes an image input control unit, which performs A/D conversion on full-color natural image information and writes it into the image memory 170.The 0-image memory 170 stores A/D-modified full-color natural images, etc., which are generally multi-tone. color image information is stored.

In the specific color region extraction means 110, 111 is an input color lookup table (input color LUT) creation section. As shown in Figure 4, the input color LUT represents each pixel of a color image with a color entry number, and each color entry has a red (red) number indicating the color information of the corresponding pixel.
R), green (G), and blue (B) data are stored. Reference numeral 112 is a color appearance frequency table creation unit in which appearance frequencies for each color are stored. Both of these input color LUTs and color appearance frequency tables are used in color image processing, and their creation methods are well known.

Reference numeral 113 denotes an area input means into which coordinate information of a specific color area to be displayed in a specific color is input. As the area input means 113, for example, a known tab left board is used.

Reference numeral 114 denotes a specific color specifying means for specifying the color portion of the specific color area when the specific color area is displayed using the color of that area. For example, a tablet board is used as the specific color specifying means, and the specific color is specified by indicating a desired specific color portion in the specific color area with a light pen.

Reference numeral 115 denotes a region extraction unit which extracts a color appearance frequency table 112.
A specific color region is extracted from the color information of the specific color region inputted by the region input means 113 or the color information of the specific color designated by the specific color designation means 114.

The extracted specific color information is added to the specific color input means 130, and the specific color area information is added to the specified color determination means 120.

In the specific color input means 130, reference numeral 131 is a composite specific color input unit which inputs an artificially synthesized specific color for displaying a specific color area. A specific color selection section 132 selects a color for displaying a specific color area. That is, when the display color of a specific color area is a color in the specific color area, the area input means 113
Alternatively, the specific color information input from the area extracting section 115 is selected in response to an input operation from the specific color specifying means 114, and when the artificial composite color is the display color, the specific color information input from the composite specific color input means 131 is selected. A composite color is selected and added to the gradation conversion means 140. These operations are performed by the image creator.
It is done manually.

The gradation conversion means 140 has an output color lookup table (output color LOT) 141 inside, and for a specific color area, a specified artificially synthesized specific color or a specific color in the specific color area. (one color), and for areas other than the specific color area, the designated color determining means 120
The gradation is converted using the (k-r) color determined by .

180 is a display unit that displays the input color image and the tone-converted color image.

(Explanation of operation) The operation in Figure 3 is performed when converting the input color image shown in Figure 2 into 16 specified colors, 4 of which are specific colors, i.e. = 16 colors, 1w 4 colors. An example of gradation conversion will be explained. Here, the sky is 210, the sea is 230, and the sand is 240.
The four areas of the leaves 251 and 251 are designated as specific color areas, and among these,
Since the sky 210 is not a single color, the closed area 2 in the sky 210
Using 11 colors as specific colors, sea 230 and sandy beach 240
are each a single color, so in the sea 230, the color of point P,
For the sandy beach 240, the color of point Q is designated as a specific color for each area, and the leaves 251 are displayed in an artificially synthesized "green" color. It is assumed that other areas are displayed in 12 specified colors that are automatically determined as colors representative of those areas.

Full-color natural image information input from the television camera 150 is A/D converted by the image input control section 160 and then stored in the image memory 170 as multi-tone color image information.

The input color LUT creation section 111 creates an input color LUT as shown in FIG. 4 based on the multi-tone color image information in the image memory 170.

The color appearance frequency table creation unit 112 uses the input color L
Create a color appearance frequency table from UT.

The image creator inputs the closed regions of the sky 211 and the leaves 215 using the region input means 113, and inputs the closed regions of the sky 211 and the leaves 215, and
4, point P on the sea 230 and point Q on the sandy beach 240 are specified, and a specific color of each area is specified.

The area extraction unit 115 extracts the color information of the specific color area input from the area input unit 113 and the color information of each specific color specified by the specific color designation unit 114 from the color appearance frequency table. By extracting each color information in each specific color area, each specific color area, that is, sky 210, sea 230,
Each region of the sandy beach 240 and the tree leaves 251 is extracted. Each extracted specific color information is added to specific color input means 130, and specific color area information is added to specified color determination means 120.

The designated color determining means 120 receives each color and its appearance frequency information from the color appearance frequency table creation section 112, and
Each specific color area information is added from the area extraction section 115.

The specified color determining means 120 uses the color information obtained by removing the color information of each specific color information from each color and its appearance frequency information and its appearance frequency information to determine the remaining color -r (=12) representing these.
Automatically determine the specified color. As a result, 12 designated colors representing areas other than the specific color area are automatically determined.

This automatic determination of the designated color can be performed, for example, by a known clustering method.

FIG. 5 explains the principle of the clustering method. The color information of each pixel of a color image is expressed as a Y (luminance) signal,
When expressed as a Q signal and a ■signal, each pixel forms a plurality of clusters in a three-dimensional coordinate space consisting of the Y, Q, and I axes, as shown in Figure 5. to be distributed.

If you specify the number of clusters and perform clustering,
The specified number of clusters are automatically formed. The color information of the centroid of each cluster is the color information representing each cluster. Therefore, in the case of this embodiment, if clustering is performed by specifying the number of clusters as 12, and the color information of each centroid of the formed 12 clusters is obtained, it is possible to specify the color information representing the area other than the specific color area. Color is automatically determined. The 12 designated colors determined in this way are the gradation converting means 14.
Added to 0.

The image creator inputs green color for displaying the tree leaves 251 using the composite specific color input means 131. Furthermore, the image creator
When the specific color selection section 132 receives the closed region information of the leaf 251 from the region input means 113, instead of the color information of the leaf 251 input from the region extraction section 115,
Composite specific color input means 13 at the color entry number
Selecting the green color input from 1, the gradation converting means 140
Add to. Closed region 2 of sky 210 from region input means 113
11 is input, the color information of the closed area 211 input from the area extraction unit 115 is selected and the gradation conversion unit 14
Add to 0. Even when the specific color specifying means 114 specifies the colors of points P and Q as specific colors for the sea 230 and the sandy beach 240, the color information of points P and Q input from the area extraction unit 115 is selected. , is added to the gradation conversion means 140.

For the specific color areas of the sky 210, the sea 230, the sandy beach 240, and the leaves 251, the gradation conversion means 140 converts each of the r(-4) colors input from the specific color selection unit 132 into corresponding specific colors. The color of the color area, and for areas other than the specific color area, the specific color determining means 120,! It was decided that it would be -r (-12) color and floor jl! , +4 conversion.

Specifically, the color output L in the gradation conversion means 140
Rewrite the UT 141 with the four specified colors and the remaining 12 specified colors. That is, in the case of an area other than the specific color area, 1
All color entries corresponding to the first color entry number in a cluster of two designated colors store color information of the designated color of that cluster. Further, in the case of a specific color area, color information of each corresponding specific color is stored in the color entry corresponding to the color entry number of each specific color area.

The tone-converted color image information output from the tone conversion means 140 is added to the color display section 180 and displayed in color. Note that when gradation conversion is not performed, the color human-powered LU created by the color human-powered car LUT creation section 111
Since the contents of T are input as they are to the color output LUT 141, the input color image is also displayed on the color display section 180.

If you want to modify or change the gradation-converted color image, you can modify or change the specified number of colors k, the specific color area, the content of the specific color, etc. as appropriate and perform the above-mentioned processing. good.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment.

For example, in addition to the methods shown in the embodiments described above, various known methods can be used to extract a specific area and determine a designated color.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be obtained.

(b) The image creator can arbitrarily select a specific color area and display that specific color area using the colors in the input color image as they are or using any artificial composite color. , it is possible to perform gradation conversion into a color image that satisfactorily reflects the intentions of the image creator.

(b) For areas other than specific color areas, a predetermined number of specified colors that best represent them can be automatically determined.
The overall color gradation conversion can be performed efficiently and quickly while reflecting the image creator's intention well.

[Brief explanation of drawings]

Figure 1...Block explanatory diagram of the configuration of the present invention, Figure 2...
. . . An explanatory diagram of an input color image of the present invention, FIG. 3 . . . An explanatory diagram of an embodiment of the invention, FIG. 4 . . . An explanatory diagram of a color lookup table used in the embodiment FIG. 5: An explanatory diagram of the clustering method used in the same example. In FIG. 1, 110... Specific color area extraction means, 120... Specific color determining means, 130... Specific color input means, 140...
Gradation conversion means.

Claims (1)

[Scope of Claims] In a gradation conversion control method for converting a multi-gradation color image into a color image having an arbitrarily specified number of color gradations smaller than the number of color gradations, (a) a color image area; (b) for a color image area other than the specific color area, a predetermined color area extracting means (110) for extracting at least one specific color area displayed in any specific color; specified color determining means (120) for automatically determining the number of specified colors; (c) specific color input means (130) for inputting a predetermined specific color for a specific color area; Regarding the area, the area to be displayed with each specified color determined by the specified color determining means (120) is automatically determined, and for the specific color area, the specified color input from the specific color input means (130) is automatically determined. A gradation conversion control method comprising: gradation conversion means (140) for inputting input.