JP3507170B2 - Image processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for performing a quantization process for representing each pixel of an input image having halftone luminance or density information by a digital value.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a configuration of a conventional image processing apparatus for performing a quantization process on an input image.

In FIG. 1, reference numeral 1 denotes a storage device (DISK) for storing the data of the image A, which is the image A stored therein.
Is a display device (LCD) according to the image A processing program 7.
6 is displayed.

A display control device (LCDC) 5 for controlling the display device 6 has a VRAM 3 for each pixel of an input image.
The pixel value is read from, the value is converted into a luminance value, and the luminance value is sent to the display device 6. The correspondence relationship between each pixel value and the brightness value is stored in the palette table 4.

The image quantization processing section 2 converts the luminance value of each pixel of the image A into a pixel value and writes it in the VRAM 3. At this time, an image quantization processing method known as a dither method or an error diffusion method is used to represent the halftone information of the image A macroscopically. Further, the correspondence relationship between each pixel value and the brightness value is determined by the image A processing program 7, written in the palette table 4 and sent to the image quantization processing unit 2. In the image quantization processing unit 2,
The pixel value of the output image is determined by referring to the correspondence between the pixel value and the brightness value.

If another image B is displayed at another position on the same screen after the image A is displayed, the image B processing program 8 uniquely associates each pixel value with the brightness value. Is determined and the contents of the palette table 4 are updated.

[0007]

By the way, in the conventional image processing apparatus configured as described above, after the digital output value of each pixel is determined by the quantization processing, each pixel is caused for some reason. Even if the correspondence between the value and the brightness is changed, the pixel value on the VRAM is not changed, so that the brightness information of the displayed image does not correctly reflect the brightness information of the input image, which is unnatural. There was a problem that it was displayed.

The present invention has been made by paying attention to the above problems, and it is possible to perform display in which the luminance information of the original image is correctly reflected even if the correspondence between each pixel value and luminance changes. It is an object of the present invention to provide an image processing device capable of

[0009]

An image processing apparatus according to the present invention performs image processing for displaying another second image at another position on the same screen after the first image is displayed. In the image processing apparatus, the first input from the storage means
Means for performing an image quantization process for converting the luminance value of each pixel of the image of 1) into a pixel value which is a digital value by referring to the correspondence between the set luminance value and the pixel value, and outputting the pixel value. And a correspondence table between the set brightness value and the pixel value is written, the palette table storing the correspondence relationship, the VRAM storing the pixel value output from the quantizing unit, and the reading from the VRAM. Display control means for converting the pixel value into a brightness value based on the correspondence stored in the palette table and outputting the brightness value to a display device, and quantization for causing the quantizing means to execute an image quantization process. When a new correspondence relationship between the brightness value and the pixel value set for displaying the second image is generated, the new correspondence relationship is provided. Together they are written to the table,
The quantization activation means, said quantization means, said storage Hand
The first image is input from the stage, the new quantization is referred to, and the image quantization process of the first image is re-executed.

Further , the image quantization processing is a dither method.
Alternatively, it is an error diffusion method, and a new
The correspondence relationship is set by the image processing program.
The new correspondence between the luminance value and the pixel value is
The position of the contrast adjuster that changes the gamma characteristic of the display device
It is set by the device.

[0011]

1 is a block diagram showing the configuration of an image processing apparatus according to a first embodiment of the present invention, and the same reference numerals as those in FIG. 7 denote the same components.

In the figure, the image A processing program 7
Is a program for displaying the image A stored in the storage device (DISK) 1 on the display device (LCD) 6 as in the conventional case, and the display control device (LCDC) 5 for controlling the display device 6 A pixel value is read from the VRAM 3 for each pixel, the value is converted into a brightness value, and the display device 6
Send to. The correspondence relationship between each pixel value and the brightness value is stored in the palette table 4.

The image quantization processing section 2 is an image quantization means for quantizing an input image and outputting its digital value.
The brightness value of each pixel of the image A is converted into a pixel value to obtain V
Write to RAM3. At this time, an image quantization processing method known as a dither method or an error diffusion method is used to represent the halftone information of the image A macroscopically. Further, the correspondence relationship between each pixel value and the brightness value is determined by the image A processing program 7 and written in the palette table 4.

Further, the quantizing starting section 9 is activated by the write signal to the palette table 4, the updated data of the palette table 4 is read and sent to the image quantizing processing section 2, and the quantizing processing is started. . The image quantization processing unit 2 determines each pixel value of the output image by referring to the correspondence relationship between each pixel value and the brightness value.

Then, after the image A is displayed,
To display another image B at another position on the same screen,
The image B processing program 8 uniquely determines the correspondence relationship between each pixel value and the brightness value, and updates the contents of the palette table 4.

At this time, the quantization starting unit 9 functions as a detecting means for detecting a change in the correspondence relationship between each pixel value and the brightness value, and the correspondence relationship between each pixel value and the brightness value changes. Image B processing program 8
Sets a new corresponding relationship between them from the palette table 4 which is the setting means, and the quantization starting section 9 which is the starting means causes the image quantization processing section 2 to re-execute the quantization processing of the image A.

That is, all write signals to the palette table 4 are sent to the quantization starting unit 9. Then, each time, the quantization starting unit 9 reads the image A from the storage device 1 and re-executes the quantization process based on the new correspondence relationship between the pixel value and the brightness value.

For example, if the image A processing program 7 sets the palette table 4 as shown in FIG. 2, the quantization processing is first executed based on these values and displayed on the display device 6. After that, if the image B processing program 8 sets the palette table 4 as shown in FIG. 3, in the conventional image processing apparatus, the brightness value changes while the pixel value of the image A remains unchanged. The display is too bright for its original brightness. However, the image processing apparatus according to the present embodiment detects that the palette table 4 has been updated, and performs the quantization processing based on the settings in FIG. 3 again, so that the original brightness information is maintained and a natural image quality is obtained. can get.

The contents of the pallet table 4 shown in FIG.
Compared with the contents of the palette table 4 in FIG. 2, the brightness value is equal to or higher than each pixel value (0 to 3), and the monochrome monochrome display is bright.

Further, assuming that the image A processing program 7 and the image B processing program 8 respectively define pixel values as shown in FIGS. 4 and 5, the same operation causes the original color information in the case of a color image. Can be kept.

In the example of FIG. 4, 1 pixel = 8 bits (b
0 to b7), b0 and b1 are bits representing the brightness of the blue component, b2, b3 and b4 are bits representing the brightness of the red component, and b5, b6 and b7 are bits representing the brightness of the green component. In the example of FIG. 5, b0 and b1 are bits representing the brightness of the blue component, b2 and b3 are bits representing the brightness of the red component, and b4, b5, b6 and b7 are the bits representing the brightness of the green component.

As described above, the quantizing means for quantizing the input image and outputting the digital value, the means for detecting the change in the correspondence between each digital value and the luminance, and the new quantizing means for each digital value and the luminance. By providing a means for obtaining the correspondence and a means for activating the image quantization processing according to the new correspondence, even if the correspondence between the pixel value and the brightness changes (changes), the change is affected. It is possible to perform display in which the brightness information of the image is correctly reflected without being displayed.

FIG. 6 is a block diagram showing the configuration of the second embodiment of the present invention, and the same symbols as those in FIG. 1 indicate the same components. In the figure, 10 is a contrast volume (variable resistance) for changing the gamma characteristic of the display device 6 including an LCD, 11 is a gamma coefficient table for storing gamma coefficients, and 12 is a quantum constituting the above-mentioned detecting means and starting means. It is an activating unit.

The relationship between the pixel value on the VRAM 3 and the brightness on the display device 6 changes when the gamma characteristic of the LCD of the display device 6 changes. The gamma characteristic changes depending on the contrast adjuster 10.

For example, the gamma characteristic is

[0026]

[Equation 1]

If the relation between the position of the contrast adjuster 10 and the value of γ is set in the gamma coefficient table 11 in advance, the relation between the brightness value E and the brightness B can be obtained. .

Further, the relation between the pixel value and the brightness value E is obtained by the palette table 4. Therefore, if the position of the contrast adjuster 10 is known, the relationship between the pixel value and the brightness B can be obtained.

Therefore, the quantization starting unit 12 detects a change in the position of the contrast adjuster 10, obtains the gamma characteristic corresponding to the detected position, further obtains the relationship with the pixel value, and obtains the information from the quantization processing unit 2. Then, the quantization processing unit 12 is activated based on the information. As a result, even if the position of the contrast adjuster 10 moves and the gamma characteristic changes, the brightness information of the original image is saved.

Therefore, in this embodiment, even if the contrast volume 10 is moved to adjust the other image B while the brightness information of the certain image A is correctly adjusted,
The brightness information of the image A is displayed as it is.

[0031]

As described above, according to the present invention ,
There is an effect that it is possible to perform a display in which the brightness information of the original image is correctly reflected without being affected by the change in the correspondence relationship between each digital value and the brightness.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the contents of a palette table set by an image A program.

FIG. 3 is a diagram showing the contents of a palette table set by an image B program.

FIG. 4 is a diagram showing pixel values defined by an image A program in the case of color display.

FIG. 5 is a diagram showing pixel values defined by an image B program in the case of color display.

FIG. 6 is a block diagram showing the arrangement of an image processing apparatus according to the second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional image processing apparatus.

[Explanation of symbols]

1 storage device 2 Image quantization processing unit (quantization means) 3 VRAM 4 Pallet table (setting means) 5 Display control device 6 Display device 7 Image A processing program 8 Image B processing program 9 Quantization activation unit (detection means, activation means) 10 Contrast volume 11 Gamma coefficient table 12 Quantization starting unit (detection means, starting means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G09G 5/14 G09G 5/00 520J (72) Inventor Tsunekazu Arai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsuhiko Sakaguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP-A-5-207305 (JP, A) JP-A-2-226192 (JP, A) ) JP-A-6-308927 (JP, A) JP-A-5-236400 (JP, A) JP-A-6-62423 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G09G 3/00-5/42 G02F 1/133 505-580

Claims (4)

(57) [Claims] 1. An image processing apparatus for performing image processing for displaying another second image at another position on the same screen after the first image is displayed, wherein the first image input from the storage means is used. Quantization for performing image quantization processing in which the luminance value of each pixel of the image of No. 1 is converted into a pixel value which is a digital value and output by referring to the correspondence relationship between the set luminance value and the pixel value. Means, a palette table storing the correspondence relationship between the set brightness value and the pixel value and storing the correspondence relationship, a VRAM storing the pixel value output from the quantizing means, and a VRAM The read pixel value is based on the correspondence relationship stored in the palette table,
Display control means for converting to a brightness value and outputting to a display device, and quantization start means for causing the quantizing means to execute an image quantization process are set, and are set for displaying the second image. When a new correspondence relationship between the brightness value and the pixel value is generated, the new correspondence relationship is written in the palette table, and the quantization starting unit causes the quantization unit to store
An image processing apparatus, wherein the first image is input from a stage, the image quantization process of the first image is re-executed by referring to a new correspondence relationship. 2. The image processing apparatus according to claim 1, wherein the image quantization processing is a dither method or an error diffusion method. 3. The image processing apparatus according to claim 1, wherein the new correspondence relationship between the brightness value and the pixel value is set by an image processing program. 4. The image processing apparatus according to claim 1, wherein the new correspondence relationship between the brightness value and the pixel value is set by the position of the contrast adjuster that changes the gamma characteristic of the display device.