JPH09200742A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable image processing suitable for real-time processing by inputting dummy data for which timing control is performed based on buffer control information. SOLUTION: Based on a compressibility parameter from an occupation rate detection part 8, input image information is compressed at an image compression part 5, converted to a variable length code VLC and outputted. Further at the image compression part 5, the bit amount of the generated VLC is outputted to a buffer control information generation part 9. In this case, corresponding to the VLC bit amount from the image compression part 5 and the buffer occupation rate from the occupation rate detection part 8, the buffer control information is calculated and outputted to a switching part 6. A buffer control information detection part 10 detects the buffer control information from a buffer 7, stops reading from the buffer 7 just for the time described in that information, controls a data selection part 11 and defines the dummy data as the output of the selection part 11.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to image processing, especially MPE.
It relates to the processing of G2 compressed images.

[0002]

2. Description of the Related Art Conventional image processing including buffer control will be described with reference to FIG. The input image information is compressed by the image compression unit 1 based on the compression ratio parameter, and the variable length code (Variable Length) is used.
h Code: VLC) and output. Switching unit 2 selectively outputs the VLC output and dummy data to buffer 3. The buffer 3 receives the input signal, that is, V
Either the LC signal or the dummy data signal is stored and output as a bit stream at a constant bit rate.
The buffer occupancy rate in the buffer 3 is detected by the occupancy rate detection unit 4, and a compression rate parameter for preventing the buffer 4 from overflowing or underflowing is calculated. This parameter is sent to the image compression unit 1.
The buffer occupancy rate is calculated by the formula (amount of buffer actually used) / (target buffer usage). The dummy data input to the switching unit 2 is an underflow of the buffer 3 when the images in which the amount of information of VLC output from the image compression unit 1 is very small are continuously input to the image compression unit 1. In order to prevent the above, the switching signal from the occupancy rate detection section 4 outputs the signal to the buffer 3 for storage. Therefore, the data is meaningless as a bit stream output from the buffer 3.

However, this method requires a large amount of dummy data to be stored in the buffer 3. Also, it is not suitable for real-time processing. That is, in real-time processing, the time for compressing one screen of data needs to be completed within one screen (for 60 images per second,
Images are input every 1/60 second, so real-time processing is not possible unless the time that can be spent compressing one image is 1/60 second or less. This is because, if the dummy data is stored in the buffer 3 by the above-mentioned method, the output of the image processing unit 1, VLC, will be kept waiting unnecessarily at the input of the switching unit 2.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide image processing suitable for real-time processing by VLC output from an image compression unit and timing-controlled dummy data input. That is, the present invention has an image compression unit that compresses image information and generates a variable-length code and its bit amount, and first and second input units, wherein the variable-length code from the image compression unit is A switching unit received by the first input unit, a buffer for inputting and temporarily storing output data from the switching unit, an occupancy detecting unit for detecting an occupancy ratio of the stored data in the buffer, and an occupancy detecting unit. Buffer control information for generating buffer control information based on the occupancy rate and the variable length code bit amount from the image compression unit and sending the buffer control information to the second input unit of the switching unit for output from the switching unit. And a buffer control information detection unit that detects that the data output from the switching unit to the buffer is buffer control information and generates a switching signal. And parts, receives the output and the dummy data from said buffer, in response to the switching signal from the buffer control information detection section, to provide an image processing apparatus including a data selector for outputting dummy data as a bit stream.

[0005]

An embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram of the image processing apparatus according to the embodiment. In the image compression unit 5, the input image information is image-compressed based on the compression ratio parameter from the occupancy ratio detection unit 8 and converted into a variable length code VLC and output. Further, the image compression unit 5 outputs the generated VLC bit amount to the buffer control information generation unit 9. The switching unit 6 selectively outputs one of the VLC from the image compression unit 5 and the buffer control information from the buffer control information generation unit 9 to the buffer 7. The buffer control information generation unit 9 calculates the buffer control information based on the VLC bit amount from the image compression unit 5 and the buffer occupancy rate from the occupancy rate detection unit 8, and the switching unit 6
Output to When it is necessary to output the buffer control information via the switching unit, a switching signal is sent. The buffer control information detection unit 10 detects the buffer control information from the data read from the buffer 7, that is, either VLC or buffer control information by pattern matching, and reads from the buffer 7 for the time described in the information. Then, the data selector 11 is stopped and the dummy data is output from the selector 11. Therefore, the buffer control information is not output from the data selection unit 11.

[0006] The buffer control information is composed of a start code, a data part, and an end code indicating that it is buffer control information, and the data part indicates time information. The time information is calculated as follows.
First, the occupation rate detection unit 8 determines the total bit amount of the image to be compressed (target total bit amount for one screen) from the occupation information from the buffer 7. Buffer control information generator 9
However, the determined total bit amount is compared with the sum of the VLC bit amounts input from the image compression unit 5 for one screen, and the difference is the time information. The compression rate parameter is determined so that the total number of bits approaches the total number of bits determined by the occupation rate detection unit 8. With the above configuration, it is not necessary to store a large amount of dummy data in the buffer 7. Further, it is only necessary to stop the reading from the buffer 7 for the time described in the buffer control information and input and output the dummy data, and it is possible to perform efficient control without having VLC unnecessarily.

FIG. 3 shows another embodiment. In this embodiment, the occupation rate is also output to the buffer control information detection unit 10. When detecting the buffer control information, the detection unit 10 determines whether or not it is now necessary to stop reading from the buffer 7 based on the input occupation rate. When the occupancy is high, it is not necessary to stop the reading, so that the reading stop command is not sent to the buffer 7 and only the buffer control information is replaced with the dummy data.
Control. Although the embodiment has been described above, the present invention is not limited to this.

[0008]

The compressed image signal can be controlled efficiently.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional image processing apparatus.

FIG. 2 is a block diagram of an image processing apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram of an image processing apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 5 image compression section 6 switching section 7 buffer 8 occupancy rate detection section 9 buffer control information generation section 10 buffer control information detection section 11 data selection section

Claims (3)

[Claims] 1. An image compression unit for compressing image information to generate a variable length code and a bit amount thereof, and first and second input units, wherein the variable length code from the image compression unit is the first 1 input section, a switching section, a buffer for inputting and temporarily storing output data from the switching section, an occupancy rate detecting section for detecting an occupancy rate of the stored data in the buffer, and an occupancy rate detecting section Buffer control information generation for generating buffer control information based on the occupancy rate and the variable length code bit amount from the image compression unit and sending the buffer control information to the second input unit of the switching unit for output from the switching unit. And a buffer control information detection unit that detects that the data output from the switching unit to the buffer is buffer control information and generates a switching signal. Parts and inputs the output and the dummy data from the buffer, the image processing apparatus comprising a data selector for outputting dummy data as a bit stream in response to the switching signal from the buffer control information detection section. 2. The image processing apparatus according to claim 1, wherein the data selection unit outputs a read stop signal to the buffer based on the buffer control information or the buffer occupation rate. 3. The image processing apparatus according to claim 1, wherein the buffer control information includes time information that specifies a time when reading from the buffer is stopped.