JPH04235468A - Picture data transmitting system - Google Patents

Abstract

PURPOSE:To improve the efficiency of compression and the quality of a repro duced picture by performing encoding and decoding operations proper to each picture in a picture data transmission system by which a picture where a continu ous multilevel image such as a color image and a binary picture such as characters coexist is transmitted through a communication channel. CONSTITUTION:This system is provided with a scanner by which an object picture is read and converted into a digital picture data, a coding means by which the digital picture data is compressed and coded and this compressed and coded picture data is expanded and decoded, a communication control means by which the compressed and encoded picture data is transferred through the communication channel and an output display means by which the picture data is outputted. The coding means is provided with a first coding means by which the picture data of the color image area is coded and a second codex means by which the picture data of the binary picture area is coded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention can handle images that are a mixture of continuous tone images such as color images and binary images such as characters.
The present invention relates to an image data transmission method for transmitting through a communication line, and is suitable for application to an image transmission device such as a color facsimile device.

0002

[Prior Art] Conventionally, encoding systems for image data transmission devices such as facsimile machines have been MH, MR, and MMR.
Encoding methods such as G
The MH code has been put into practical use as a standard encoding method for G3 standard facsimile machines, and the MMR code has been put into practical use as a standard encoding method for G4 standard facsimile machines. Recently, as binary image encoding systems for soft copy communication, CCITT and encoding systems that can display a rough overall image at an early stage and then gradually improve its image quality with progressive build-up display have been developed. It is proposed by the ISO joint organization JBIG (PCSJ89,
Image Coding Lecture Proceedings, PP. 61-66).

[0003] DCT (discrete cosine transform) is also used as a highly efficient encoding method for continuous tone images such as full-color images.
A color still image encoding method using
7)).

0004

[Problem to be Solved by the Invention] However, when encoding and transmitting an image containing a mixture of binary images and continuous tone images, it is difficult to encode the entire image using a coding method for continuous tone images. In this case, the compression efficiency of binary image parts such as characters cannot be improved, and a decoded image with good quality cannot be obtained in the parts such as characters.

[0005] The purpose of the present invention is to improve the compression efficiency and the quality of the reproduced image by performing encoding and decoding processing suitable for each when transmitting an image in which a picture part and a character part coexist. shall be.

[0006]

[Means for Solving the Problems] An image data transmission system according to the present invention includes a scanner that reads a target image and converts it into digital image data, compression encoding of the digital image data, and decompression decoding of the compression encoded image data. a communication control means for transmitting and receiving the compressed and encoded image data through a communication line, and an output display means for outputting an image based on the image data, the codec means for converting the image data into a continuous tone image area. a first codec means for codecing the image data of the binary image area; and a second codec means for codecing the image data of the binary image area.
codec means.

[0007]

[Operation] In this configuration, at the time of transmission, a target image is read by a scanner, the obtained image data is stored in an image memory, and simultaneously displayed on an output display means such as a CRT display device. The user specifies a continuous tone image area such as a color image area while viewing the image displayed on the CRT screen, and separates it from a binary image area such as a character image area. Next, the separated color image area and character image area are transferred to codec means, the image data of the color image area is encoded by the first codec means, and the image data of the character image area is encoded by the second codec means. do. The encoded image data is sequentially transferred to the communication control means and sequentially transmitted through the communication line.

At the time of reception, when the communication control means detects the arrival of image data from the communication line, the codec means is activated to decode the image data transferred from the communication control means. The decoded image data is sequentially written into the image memory, and when all the image data has been written, an output display means such as a plotter device is activated and output.

Writing image data to the image memory is as follows:
After decoding and writing the image data in the character image area,
The image data of the color image area is overwritten on the image memory based on the position data sent at the same time to restore the original image in which a binary image and a continuous tone image are mixed.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of an image data transmission system according to the present invention. In FIG. 1, a system bus 1 includes a system control section 2 for controlling the operation of the entire system, a communication control section 4 having an ISDN interface configuration for sending and receiving image data via a telephone line 3, and a communication control section 4 for transmitting and receiving image data through a telephone line 3. A scanner unit 5 that optically reads and generates digital image data, an image memory unit 6 that stores various image data, a codec unit 7 that performs encoding/decoding processing of image data, and an input image or processed image data. A plotter unit 8 for printing out images and a CRT display unit 9 for displaying input images or processed images are connected to each other, and a mouse 10 as a pointing device is connected to the display unit 9. ing. Further, connected to the system control section 2 is an operation section 11 provided with an operator for controlling the system and a display section for displaying the status of the system.

The codec unit 7 is provided with a first codec unit for continuous tone images and a second codec unit for binary images.The codec units for continuous tone images include CCITT and CCITT. The codec unit (hereinafter referred to as JPEG codec unit) based on the color still image encoding method proposed by JPEG, a joint organization of ISO, is the codec unit for binary images, and the codec unit for binary images is based on the binary image encoding method proposed by JBIG, a joint organization of CCITT and ISO. A codec unit (hereinafter referred to as a JBIG codec unit) based on an image encoding method is provided.

Next, the operation of the image data transmission system shown in FIG. 1 will be explained with reference to the flowcharts shown in FIGS. 2 and 3.

In the configuration of FIG. 1, at the time of transmission, the system control section 2 detects a transmission command from the operation section 11 (step 20), and activates the scanner section 5 (step 21). The scanner section 5 starts reading the target image (step 22), and stores each of the three primary colors RGB as 8-bit data in the image memory section 6 (step 23).

The CRT display section 9 converts the image stored on the image memory section 6 into a CR while performing density conversion.
T (step 24). While looking at the image displayed on the CRT screen, the user uses the mouse 11 to specify a color image area (continuous tone image area), and then selects a character image area (
binary image area) (step 25). The system control unit 2 transfers the image data of the color image area and character image area separated by the display unit 9 to the codec unit 7, and instructs the codec unit 7 to start encoding.

[0015] In the codec section 7, the image data of the color image area among the received image data is encoded by the JPEG codec section, and the image data of the character image area is encoded with the JPEG codec section.
It is encoded by the G codec unit (step 26). The encoded image data is sequentially transferred to the communication control section 4 and sequentially transmitted through the telephone line 3 (step 27). When the transmission of all image data is completed (step 28), the system control unit 2 notifies the operation unit 11 of the completion, returns to the standby state, and ends the transmission process (step 29).

[0016] In the encoding of the image data in step 26, first, the color image area is regarded as a blank area, and the entire image area is converted into binary image data, and an encoding method for binary images such as the JBIG method is used. Compression encoding is performed using Next, a color image encoding method such as the JPEG method is applied to the color image area to perform compression encoding. In this case, prior to transmitting the image data of the color image area, data indicating the position of the separated color image area is also transmitted.

At the time of reception, when the communication control section 4 detects the arrival of image data from the telephone line 3 (step 40),
The communication control unit 4 communicates with the system control unit 2 while performing the receiving operation.
(Step 41). The system control unit 2 instructs the operation unit 11 to display that reception is in progress, and activates the codec unit 7 (step 42). The codec section 7 starts reading the image data transferred from the communication control section 4, sequentially decodes it into RGB data (step 43), and sequentially writes the decoded image data into the image memory section 6 (step 44).

When the communication is completed (step 45) and all the image data is developed on the image memory section 6, the system control section 2 starts up the plotter section 8 (step 46).
, and print it out (step 47). When all image data has been printed out (step 48)
, the system control unit 2 notifies the operation unit 11 of the termination (
Step 49) returns to the standby state and ends the reception process.

Writing the image data into the image memory section 6 in step 44 involves decoding the binary image data, and then writing the decoded color image data onto the image memory section 6 based on the position data sent at the same time. to restore the original image.

Note that in this configuration, the encoding method of the input image can be changed for each screen (document unit). That is, if a certain screen is all binary images, a binary image encoding method is used, and if all other screens are color images, a color image encoding method is used. When transmitting, data of the encoding method used in each document is sent.

[0021]

Effects of the Invention According to the present invention, when transmitting an image in which a picture area and a character area coexist, encoding is performed that is appropriate for each image area, thereby improving compression efficiency and improving the quality of the reproduced image after decoding. It becomes possible to aim for qualitative improvement.

[Brief explanation of the drawing]

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

FIG. 2 is a flowchart for explaining the operation during transmission in FIG. 1;

FIG. 3 is a flowchart for explaining the operation at the time of reception in FIG. 2;

[Explanation of symbols]

1 System bus 2 System control section 3 Telephone line 4 Communication control section 5 Scanner section 6 Image memory section 7 Codec section 8 Plotter section 9 CRT display section 10 Mouse 11　　　　Operation section

Claims (4)

[Claims] 1. A scanner that reads a target image and converts it into digital image data; a codec means that compresses and encodes the digital image data and decompresses and decodes the compressed and encoded image data; a communication control means for transmitting and receiving converted image data; and an output display means for outputting an image based on the image data; A second codec for codecing the image data in the value image domain.
An image data transmission method comprising: codec means. 2. The image forming apparatus according to claim 1, further comprising means for separating the target image into a color image area and a binary image area,
An image data transmission system characterized in that the image data of each separated image area is compressed and encoded according to each area by the first and second codec means. 3. In claim 2, the transmitting side transmits the first
and the respective image data compressed and encoded by the second codec means, and the receiving side decompresses and decodes each of the transmitted image data by the first and second codec means, and the decompressed and decoded image data is transmitted. An image data transmission method characterized in that image data of each image area is restored to the correct position of the target image. 4. The image data transmission system according to claim 1, wherein the codec means encodes the target image document by document using an encoding method depending on each document.