JPH04301972A - Pictorial communication equipment - Google Patents

Abstract

PURPOSE:To confirm the picture quality of an image transmitted to the equipment of a communicating party by an operator and to reduce the mental burden of the operator by providing a means to calculate the density change of the color image, calculating the part of the large density change to easily degrade the image and executing the compression, extension and display of the part. CONSTITUTION:A scanner part 1 inputs the color image and transmits color image data to a density change discrimination part 2. The discrimination part 2 divides the color image into the blocks of 128X128 dots, for example, calculates the density changes at the respective blocks and calculate the block having the largest density change. A compression part 3 compresses the color image data and transmits the compressed data to a communication control part 4, and the control part 4 executes the communication with the equipment of the communicating party and transmits the compressed color image data. An extension part 5 extends the compressed color image data and transmits an image corresponding to the block, which is calculated by the discrimination part 2, having the large density change to a display part 6, and the display part 6 displays the image.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication apparatus, and more particularly to an image communication apparatus having means for compressing and transmitting image data.

0002

[Prior Art] Conventionally, among image communication devices that communicate image data, there has been no device that simply compresses the image and then transmits it, and that the transmitting side expands the image data and displays the image. .

0003

[Problems to be Solved by the Invention] Therefore, when communicating a color image, the operator does not know what kind of image quality the color image will be sent to the other party's machine, which places a heavy mental burden on the operator. In particular, the problem was serious in color image communication because, unlike in black and white, irreversible compression is performed.

[0004] An object of the present invention is to provide an image communication device in view of this point.

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention provides a means for compressing given image data, a means for decompressing the image data compressed by the means, and a means for decompressing the image data after compressing the image. and display means for expanding the image area and displaying the image.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, 1 is a scanner section, 2 is a density change determination section, 3 is a compression section called, for example, ADCT system, 4 is a communication control section, 5 is an extension section, and 6 is a display section.

[0007] The scanner section 1 inputs a color image and sends the color image data to the density change determination section 2 . In this embodiment, a color image is input at 400 dpi, and each dot data is expressed in 256 steps from 0 to 255 for each of RGB. Therefore, for example, in a 10 inch x 10 inch image, the number of dots is 4000 x 4000.
Equivalently, each dot is generated as 24-bit data.

[0008] The density change determination unit 2 converts the color image into 12
Divide into blocks of 8 x 128 dots, find the density change in each block, and find the block with the largest density change.

The compression section 3 compresses the color image data and sends it to the communication control section 4.

[0010] The communication control unit 4 communicates with the other party's device,
Send compressed color image data.

The decompressing section 5 decompresses the compressed color image data and sends an image corresponding to a block with a large density change determined by the density change determining section to the display section.

[0012] The display section 6 displays images.

FIG. 2 is a flowchart showing the operation of the density change determination section. The color image input in step S7 is divided into blocks of 128×128 dots. As mentioned above, if the original image is 4000 x 4000 dots, it is 32 x 3.
The image is divided into two image areas. In step S8, RGB is changed to YUV in each block, and in step S9, the average value of Y is determined in each block, and in step S1
0, the standard deviation of Y is determined in each block, and in step S11, the block with the largest standard deviation is determined to be the part with the largest density change.

FIG. 3 is a diagram showing matrix calculation for obtaining YUV from RGB.

[0015] In this embodiment, since the expanded/contracted/expanded image is displayed for the portion where the density change is large, the image quality can be checked, especially for the portion where the image deterioration due to compression is severe. (Example 2) In the previous example, blocks with large density changes were determined based on the standard deviation of Y within the block, but for each dot within the block, the sum of the absolute values of the differences in Y from the surrounding dots was calculated. It is also possible to find blocks with large density changes based on the average value. In the example in Figure 4, the sum of the absolute values of the difference in Y between the central dot and the surrounding dots is 20+
20+50+70=160. (Embodiment 3) In the above embodiment, the entire image is expanded in the expansion section, but the expansion may be stopped when an expanded image of a block with a large density change is obtained. (Embodiment 4) In the above embodiment, the compressed color image data is expanded for the entire image, but it is also possible to extract only the portion with a large density change from the original color image, compress it, and expand it. . (Embodiment 5) In the above embodiment, transmission of compressed images and compression/
Although the decompressed images are displayed separately, a means for the operator to instruct confirmation may be provided, and after the compressed and decompressed images are displayed, the operator instructs the confirmation to be transmitted. (Embodiment 6) In Embodiments 4 and 5, only the portion with a large density change may be first compressed, expanded, and displayed, and after confirmation by the operator, the entire color image may be compressed and transmitted. (Embodiment 7) In the above embodiment, only transmission was performed, but reception may also be possible. (Embodiment 8) In the above embodiments, images were input from the scanner unit, but a video camera or still video camera may be connected and images may be input.

Further, the compression method is not limited to the above-mentioned example, but may be vector quantization or another method such as DPCM method.

As explained above, according to the present embodiment, a means for compressing a color image, a means for decompressing the compressed color image, and a means for displaying the image are provided, and the color image after compression and decompression is displayed. In particular, it is equipped with a means to determine density changes in color images, and compresses, expands, and displays parts with large density changes where image quality is likely to deteriorate, allowing the operator to check the image quality of the image sent to the other party's machine. You can reduce your mental burden.

[0018]

According to the present invention, even when transmission is performed after irreversible compression/expansion, image transmission can be performed satisfactorily.

[Brief explanation of drawings]

[Fig. 1] Configuration diagram of one embodiment of the present invention

[Figure 2] Flowchart showing the operation of the concentration change determination section

[
Figure 3: Determinant for changing from RGB signal to YUV signal

FIG. 4 is a diagram showing an example for determining the difference in Y from surrounding dots.

[Explanation of symbols]

1 Scanner section 2 Concentration change determination section 3 Compression section 4 Communication control section 5 Extension part 6 Display section

Claims (3)

[Claims] 1. Means for compressing given image data; means for decompressing image data compressed by the means;
An image communication device comprising: a display unit that compresses an image, expands a specific image area, and displays the image. 2. The image communication apparatus according to claim 1, wherein the specific image area is a part where density changes are large. 3. The image communication device according to claim 1, wherein the provided image data is color image data.