JPH04298196A - Color picture information compression display method - Google Patents

Abstract

PURPOSE:To improve display quality of compressed color picture information displayed on a color picture display screen. CONSTITUTION:Color original picture information is converted into compressed color picture information expressed in less color number than that of the color original picture information, a prescribed color number is extracted in the order of higher appearance in the color included in the color original picture information or intermediate compression color picture information and a color map is generated based on the extracted color and the color original picture information or the intermediate compression color picture information is converted into the compressed color picture information based on the color map and displayed on a color picture display screen. Thus, the display quality of the compressed color picture information displayed on the color picture display screen is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image display method, and more particularly to a method for compressing and displaying color image information in a color image display device.

0002

2. Description of the Related Art In a conventional method for compressing and displaying color image information of this type, for example, color original image information is converted into compressed color image information and displayed as a color image in accordance with a processing procedure consisting of five steps shown in FIG. Display on the device. Figure 9
A method for compressing and displaying color image information will be explained according to the flowchart.

First, in step 41, full color (16
777,216 colors) into compressed color image information expressed using 256 preset colors, and each pixel forming the display screen of a color image display device that can simultaneously display the compressed color image information in 256 colors. Create a color information conversion table (hereinafter referred to as a color map) for converting into values. When the full-color original image information is input in step 42, in step 43, according to the color map,
The original image information is converted into compressed color image information expressed using the 256 colors. In step 44, this compressed color image information is used to determine the pixel value of each pixel on the display screen of a color image display device capable of simultaneously displaying 256 colors. At this time, colors other than the 256 colors in the original image information are considered to be the same color as the closest color among the 256 colors, and are converted. Finally, in step 45, according to the pixel value of each pixel on the display screen of the color image display device determined as described above, the compressed color image information of the 256 colors is displayed on the display screen of the color image display device that can display 256 colors simultaneously. Display.

0004

However, in the conventional color image information compression display method, when converting full-color original image information into 256-color compressed color image information,
Since 256 colors are determined regardless of the original image information, 2
When compressed color image information of 56 colors is displayed on a color image display device, there is a problem in that the quality of the displayed image deteriorates.

An object of the present invention is to provide a technique that can improve the display quality of compressed color image information displayed on a color image display screen.

The above and other objects and novel features of the present invention will become clear from the description of this specification and the accompanying drawings.

[0007]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, color original image information is converted into compressed color image information expressed with a smaller number of colors than the color original image information according to a color map. In the color image information compression display method for displaying this on a color image display screen, the frequency of appearance of colors included in the color original image information is calculated for the color original image information, and the colors are displayed in descending order of appearance frequency. A predetermined number of colors are extracted from the color original image information, a color map is created using only the extracted color or the extracted color and at least one preset color, and the color map is used to create a color map using the color map. It is characterized by converting original image information into compressed color image information expressed using fewer colors than the color original image information and displaying the compressed color image information on a display screen.

[0008] Furthermore, the color original image information is compressed into intermediate compressed color image information expressed by a number of colors less than the number of colors of the color original image information and more than the number of colors of the compressed color image information, and the intermediate compressed color image information is The appearance frequency of the color included in the information is calculated for the intermediate compressed color image information, a predetermined number of colors to be displayed in order of frequency of appearance are extracted from the intermediate compressed color image information, and only the extracted color or the relevant color is displayed. Compressed color in which a color map is created using the extracted color and one or more colors set in advance, and the intermediate compressed color image information is expressed using a smaller number of colors than the intermediate compressed color image information using the color map. It is characterized by converting it into image information and displaying it on the display screen.

[0009]

[Operation] According to the above-mentioned means, a color map used for converting color original image information into compressed color image information and displaying it on a color image display device can be created by The color image information is determined based on the frequency, and the color map is used to convert the color original image information into compressed color image information expressed with fewer colors than the color original image information, and the compressed color image information is displayed on the display screen. The display quality of compressed color image information displayed on the screen can be improved.

[0010] Further, the color map is determined based on the frequency of appearance of all colors included in the intermediate compressed color image information,
The intermediate compressed color image information is converted into compressed color image information expressed using fewer colors than the intermediate compressed color image information using the color map and displayed on the display screen, so that the intermediate compressed color image information is displayed on the color image display screen. The display quality of compressed color image information can be improved.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

[Embodiment 1] FIG. 1 is a flowchart for explaining the processing procedure in a color image information compression display method according to Embodiment 1 of the present invention, and FIG. FIG. 3 is a block diagram showing the functional configuration of the implementation device of FIG. 2.

As shown in FIG. 2, the apparatus for implementing the color image information compression and display method of the present invention includes an image input device 101 for inputting color original image information;
a frame memory 102 for storing the input color original image information; an analog/digital converter (A/D) 103 for converting the input color original image information into a digital signal; An electronic computer 104 for compressing digital signals of color original image information, displaying color image information, creating color maps, controlling various parts, etc.; color image information;
Display device (display) 1 that displays bitmaps, etc.
05, an image information file 106 that stores color image information and various data.

As shown in FIG. 3, the functional configuration of the present apparatus includes an image input section 201 that inputs color image information using the image input device 101 such as a video camera, and an image input section 201 that inputs color image information of the input analog signal. An analog/digital converter 202 that converts the digital data into digital data using a digital converter (A/D) 103 calculates the appearance frequency of colors included in the color original image information and creates a color appearance frequency table. The color appearance frequency table creation unit 203 extracts a predetermined number of colors to be displayed from the color original image information in descending order of appearance frequency, and presets only the extracted color or the extracted color. A color map creation unit 204 that creates a color map using at least one color, and a pixel that uses the color map to convert the color original image information into compressed color image information that is expressed with fewer colors than the color original image information. It is composed of a value conversion section 205, an image display control section 206, and an image display section 207. The appearance frequency table creation section 203, color map creation section 204, pixel value conversion section 205, and image display control section 206 are
This is the functional configuration of 4.

Next, a method for compressing and displaying color image information according to the first embodiment using the apparatus shown in FIGS. 2 and 3 will be described.

As shown in FIG. 1, the method for compressing and displaying color image information according to the first embodiment starts with step 1, in which full colors (16777216 colors) are expressed by 8 bits each of the three primary colors of light, red, green, and blue. ) When the original image information is input, in step 2, the frequency of appearance of the colors included in the full-color original image information is calculated. FIG. 4 shows an example of the appearance frequency distribution calculated in this way. In FIG. 4, the horizontal axis represents colors expressed by combinations of 8 bits each for red, green, and blue, and the vertical axis represents the frequency of appearance of the colors. The colors A1, A2, A3, ... AN-1, AN expressed by a combination of 8 bits each of red, green, and blue on the horizontal axis are as follows:
For example, it is represented by a color bit display as shown in FIG.

Next, in step 3, the full color (
16777216 colors) The original image information is compressed into 256 colors of color image information, and this compressed color image information is expressed.
It is determined whether there is a color specified in advance to be used among the 56 colors. If the specified color does not exist, the process moves to step 4, and 256 colors are extracted in order of frequency of appearance calculated in step 2. This extracted 25
Compressed color image information is expressed using six colors. After this,
Processing moves to step 7. If one or more colors have been specified in step 3, the subsequent process moves to step 5. In step 5, if the specified number of colors is X, then (256-X) colors are extracted in order of the frequency of appearance of the colors calculated in step 2, and in step 6, the extracted (256-X) colors are extracted. and the pre-specified X color 2
Decide on 56 colors. Compressed color image information is expressed using these 256 colors. After this, the process moves to step 7. In step 7, the full-color original image information is converted into compressed color image information of the determined 256 colors, and this compressed color image information is converted into the pixel value of each pixel constituting the display screen of a color image display device that can display 256 colors simultaneously. Create a colormap for conversion. In step 8, full-color original image information is created using this color map.
Converts to compressed color image information of 56 colors. At this time, colors other than the 256 colors in the full-color original image information are considered to be the same as the closest color among the 256 colors, or the colors other than the 256 colors are converted. Assigns the same color as neighboring pixels to a pixel with

In step 9, the compressed color image information is used to determine the pixel value of each pixel on the display screen of a color image display device capable of simultaneously displaying 256 colors. Finally, in step 10, the 256-color compressed color image information is displayed on the display screen of a color image display device capable of simultaneously displaying 256 colors in accordance with the pixel values.

As can be seen from the above explanation, this embodiment 1
According to the color image information compression display method, when converting full-color original image information into 256-color compressed color image information, colors that appear frequently in the full-color original image information are extracted, and the extracted colors are A color map is created based on this, and the full-color original image information is converted into compressed color image information of 256 colors. In this way, a color map is created based on the full-color original image information, and according to this, the full-color original image information is converted into compressed color image information and displayed on the color image display device, so a high-quality image is displayed. be able to.

[Embodiment 2] FIG. 6 is a flowchart for explaining the processing procedure in a color image information compression display method according to Embodiment 2 of the present invention.

In the color image information compression display method of the second embodiment, as shown in FIG. It is converted into intermediate compressed color image information of the set 4096 colors. Here, the 4096 colors of the intermediate compressed color image information are determined, for example, by the following method. The 16777216 colors of full-color original image information are the three primary colors of light: red, green,
Each blue color is represented by 8 bits. This 167772
One way to compress and classify 16 colors into 4096 colors is to
This method uses the upper 4 bits of each of red, green, and blue. In other words, colors in which the upper 4 bits of each of the three primary colors match are considered to be the same color and are classified. Using this method, 4096 colors are determined.

Next, in step 23, the frequency of appearance of 4096 colors is calculated in the intermediate compressed color image information obtained as described above. FIG. 7 shows an example of the calculated appearance frequency distribution. In FIG. 8, the horizontal axis represents colors expressed by combinations of 4 bits each for red, green, and blue. In step 24, it is determined whether or not there is a color designated in advance for use among the 256 colors expressing compressed color image information. If the specified color is not available, proceed to step 2.
The process moves to step 5, where 256 colors are extracted in order of the frequency of appearance of the colors calculated in step 23. This extracted 25
Compressed color image information is expressed using six colors. After this, the process moves to step 28. If one or more colors are specified in step 24, the process then moves to step 26. In step 26, if the specified number of colors is X, then (256-X) colors are extracted from the 4096 colors in order of frequency of appearance calculated in step 23. In step 27, the extracted (256-X
) color and the previously specified X color, 256 colors are determined. Compressed color image information is expressed using these 256 colors. After this, the process moves to step 28. In step 28, the intermediate compressed color image information of 4096 colors is converted into compressed color image information of the determined 256 colors, and each pixel constituting the display screen of the color image display device capable of displaying the compressed color image information of 256 colors simultaneously. Create a color map to convert to pixel values. In step 29, this color map is used to convert intermediate compressed color image information of 4096 colors into compressed color image information of 256 colors. At this time, colors other than the 256 colors among the 4096 colors of the intermediate compressed color image information are considered to be the same as the closest color among the 256 colors, or are converted using the 256 colors. Assign the same color as neighboring pixels to pixels that have a color other than . In step 30, the pixel value of each pixel on the display screen of a color image display device capable of simultaneously displaying 256 colors is determined using the compressed color image information. Finally, according to this determined pixel value in step 31,
The 256-color compressed color image information is displayed on a display screen of a color image display device capable of displaying 256 colors simultaneously.

As can be seen from the above explanation, this embodiment 2
In the color image information compression display method, full-color original image information is converted to intermediate compressed color image information of 4096 colors,
Thereafter, the 4096 colors of this intermediate compressed color image information are converted into compressed color image information of 256 colors. When converting intermediate compressed color image information of 4096 colors to compressed color image information of 256 colors, colors that appear frequently in the intermediate compressed color image information are extracted, and a color map is created based on the extracted colors. This is used to convert the 4096 colors of the intermediate compressed color image information into compressed color image information of 256 colors. Here, full color original image information is 409
As in the first embodiment, full color (16777216 colors) is once converted to intermediate compressed color image information of 6 colors.
This is to avoid the fact that when calculating the appearance frequency of a color included in the original image information, the amount of memory and calculation load of the computer required for the calculation tends to increase. Even if the full-color original image information is once converted into intermediate compressed color image information of 4096 colors, the intermediate compressed color image information has much higher definition than the compressed color image information of 256 colors. A color map is created based on the colors that appear frequently included in the compressed color image information, and the intermediate compressed color image information is
Since it is converted into compressed color image information of six colors and displayed on a color image display device, it is possible to display a high quality image.

Although the present invention has been specifically explained above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples, and can be modified in various ways without departing from the gist thereof. do not have.

[0025]

As explained above, according to the present invention, color original image information is converted into compressed color image information expressed using fewer colors than the color original image information, and the color original image information or Among the colors included in the intermediate compressed color image information, a predetermined number of colors are extracted in order of frequency of appearance, a color map is created based on the extracted colors, and the color original image is created based on this color map. Since information or intermediate compressed color image information is converted into compressed color image information and this is displayed on a color image display screen, the quality of the displayed color image can be improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart for explaining a processing procedure in a color image information compression display method according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of an implementation device for implementing the color image information compression and display method of the present invention.

FIG. 3 is a block diagram showing the functional configuration of the implementation device of FIG. 2;

FIG. 4 is a diagram showing an example of a calculated distribution of appearance frequencies of colors included in full-color original image information according to the first embodiment.

[Fig. 5] Colors A1, A2, A3, . . . expressed by combinations of 8 bits each of red, green, and blue on the horizontal axis in Fig. 4;
FIG. 6 is a diagram showing an example for explaining color bit display of AN-1 and AN.

FIG. 6 is a flowchart for explaining a processing procedure in a color image information compression display method according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of a calculated appearance frequency distribution of 4096 colors included in intermediate compressed color image information according to the second embodiment.

[Fig. 8] Colors A1, A2, A3, . . . expressed by combinations of the upper 4 bits of each of red, green, and blue on the horizontal axis in Fig. 7;
... is a diagram showing an example for explaining color bit display of AN-1 and AN.

FIG. 9 is a flowchart for explaining problems in a conventional color image information compression display method.

[Explanation of symbols]

101... Image input device, 102... Frame memory, 10
3...Analog/digital converter (A/D), 104...
Electronic computer, 105... Display device (display), 10
6... Image information file, 201... Image input section, 202...
Analog/digital conversion section, 203... Appearance frequency table creation section, 204... Color map creation section, 205... Pixel value conversion section, 206... Image display control section, 207... Image display section.

Claims (2)

[Claims] 1. A color image in which color original image information is converted into compressed color image information expressed with fewer colors than the color original image information according to a color information conversion table, and this is displayed on a color image display screen. In the information compression display method, the appearance frequency of colors included in the color original image information is calculated for the color original image information, and a predetermined number of colors to be displayed in descending order of appearance frequency are extracted from the color original image information. , create a color information conversion table using only the extracted color or the extracted color and at least one preset color, and use the color information conversion table to convert the color original image information from the color original image information. A color image information compression display method characterized by converting the compressed color image information expressed using a small number of colors and displaying the compressed color image information on a display screen. 2. Compressing color original image information into intermediate compressed color image information expressed by a number of colors less than the number of colors of the color original image information and more than the number of colors of the compressed color image information, The frequency of appearance of colors included in the image information is calculated for the intermediate compressed color image information, a predetermined number of colors to be displayed in order of frequency of appearance are extracted from the intermediate compressed color image information, and only the extracted colors or Create a color information conversion table using the extracted color and one or more colors set in advance, and use the color information conversion table to convert the intermediate compressed color image information into colors smaller than the intermediate compressed color image information. A method for compressing and displaying color image information, characterized by converting it into compressed color image information expressed in numbers and displaying it on a display screen.