Image processing system

• US 5,801,776 A
• Filed: 03/16/1995
• Issued: 09/01/1998
• Est. Priority Date: 03/25/1993
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Tamura, Tsuyoshi, Ishikawa, Teruhisa, Miyane, Toshiki
• Primary Examiner(s): AU, AMELIA MEGAN
• Application Number:
  US08/405,348
• Time in Patent Office: 1,265 Days
• Field of Search: 348/384, 348/390, 348/391, 348/395, 348/400, 348/401, 348/403, 348/409, 348/415, 348/420, 348/714, 348/715, 348/716, 382/232, 382/233, 382/235, 382/236, 382/238, 382/244, 382/245, 382/246, 382/248, 345/185, 345/189, 345/201, 345/202, 345/203, 345/196, 345/200, 358/335
• US Class Current: 375/240.18
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

The present invention provides an image decoding and reconstruction system for successively reading out and decoding compression video data constituting one screen page and reconstructing an image with a memory of a small capacity. The system of the invention divides an image of one screen page into 8×8-pixel blocks, compresses video data by discrete cosine transform, successively reads data in the unit of a 2×2 matrix of the 8×8-pixel blocks, and stores the video data along horizontal scanning lines in one of two memories while reading other video data previously stored along the scanning lines out of the other memory. The invention also provides an interblock distortion removal filter for eliminating interblock distortions due to orthogonal transform. The filter eliminates interblock distortions generated on the boundary between vertically adjacent blocks in each 16-line data area before writing video data in the memory, and eliminates distortions between horizontally adjacent blocks in the data area when reading video data out of the memory. The filter also eliminates interblock distortions on the boundary between adjacent 16-line data areas by reading last line data of a first block out of one memory while reading first line data of a second block out of the other memory.

Claims

1. An image decoding system for decoding compression data to video data, said compression data being generated by dividing original video data constituting one screen page of video data into a plurality of pixel blocks and coding said video data on a block by block basis, each block consisting of an array of M by N pixels with M and N being integers greater than 2, said image decoding system comprising:

compression data input means for inputting said compression data which was previously coded on a block by block basis, along a predetermined direction of an image;

decoding means for decoding said input compression data to video data corresponding to each said block at a first timing;

memory means for storing and arranging said decoded video data, said memory means including two memory elements working alternately, the combined memory storage capacity of said two memory elements being smaller than the memory capacity required to store one full screen page of video data, each of said memory elements being large enough to store a block line of video data which corresponds to only a portion of said screen page of video data, said block line of video data being made up of at least M lines of video data; and

reading means for successively reading said block lines of said video data out of said memory means at a second timing different from said first timing for decoding, said reading means including means for reading said video data from one of the memory elements during a time when said video data is not being stored into that memory element.

2. An image decoding system in accordance with claim 1, wherein said memory means comprises means for making said decoded video data readable in a unit of two times M lines when decoding of two block lines of said compression data along said predetermined direction is completed by relocating the decoded video data in an address which corresponds to a location of the video data after decoding, and storing the video data in a memory.

3. An image decoding system in accordance with claim 1, said system further comprising means for specifying said video data generated by decoding said compression data as ineffective data or transparent data or means for inactivating said reading means to prevent said video data from being read out of said memory means when a process of storing and arranging said decoded video data in said memory means is not completed at said second timing.

4. An image decoding system in accordance with claim 1, wherein said decoding means comprises:

at least two decoding elements using different decoding processes; and

decoding element activation means for selectively activating and using only one of said at least two decoding elements to decode said compression data based on information of a decoding process recorded in said compression data.

5. An image decoding system in accordance with claim 1, wherein said reading means comprises synchronous reading means for reading out each line of decoded video data synchronously with a synchronizing signal output from an external display unit;

and

said synchronous reading means further comprising synchronous timing setting means for setting a timing of synchronization with said synchronizing signal.

6. An image decoding system for decoding compression data to video data, said compression data being generated by dividing original video data constituting one screen page of video data into a plurality of pixel blocks and coding said video data by each block, each block consisting of an array of M by N pixels with M and N being integers greater than 2, said image decoding system comprising:

compression data input means for inputting said compression data previously coded by each block, along a predetermined direction of an image;

decoding means for decoding said input compression data to video data corresponding to each said block at a first timing, said decoding means including (i) at least two decoding elements using different decoding processes and (ii) decoding activation means for selectively activating and using only one of said at least two decoding elements to decode said compression data based on information of a decoding process recorded in said compression data, one of said at least two decoding elements comprises means for decoding compression data generated by orthogonally transforming original video data by every M by N pixel block, dividing said transformed video data into numeral data and a length of continuity of zero data, and Huffman coding the divided data and the other of said at least two decoding elements comprising means for decoding compression data generated by run-length coding original video data constructed as a combination of a numeral representing a color and a length of continuity of the color;

memory means for storing and arranging said decoded video data to make said decoded video data readable in a unit of at least M lines when decoding of said compression data along said predetermined direction is completed, said unit of at least M lines corresponding to only a portion of said screen page; and

reading means for successively reading said video data of at least M lines out of said memory means at a second timing different from said first timing for decoding.

7. An image decoding system for decoding compression data to video data, said compression data being generated by dividing original video data constituting one screen page of video data into a plurality of pixel blocks and coding said video data on a block by block basis, each block consisting of an array of M by N pixels with M and N being integers greater than 2, said image decoding system comprising:

an input circuit for inputting said compression data, which was previously coded on a block by block basis, along a horizontal scanning direction of a display unit;

a decoder for decoding said input compression data to video data blocks corresponding to said pixel blocks;

a memory for storing and aligning said decoded video data blocks, each consisting of M by N pixels, along said scanning direction, said memory means including two memory elements working alternately the combined memory storage capacity of said memory elements being smaller than the memory capacity required to store one full screen page of video data, each of said memory elements being large enough to store a block line of video data which corresponds to only a portion of said screen page of video data, said block line of video data being made up of at least M lines of video data;

a memory switcher circuit for storing one block line of video data along said scanning direction in one of said memory elements, and storing another block line of video data along said scanning direction in the other of said memory elements; and

a reading circuit for reading data of each pixel along said scanning direction of said display unit out of said video data previously stored in said memory, at a second speed lower than the first speed, said reading circuit including a read switcher circuit for reading one line of video data from one of said memory elements while storing another line of video data in the other of said memory elements.

8. An image decoding system in accordance with claim 7, said decoder further comprising:

at least two decoding elements using different decoding processes; and

a decoding element activator for selectively activating and using only one of said at least two decoding elements to decode said compression data based on information of a decoding process recorded in said compression data.

9. An image reconstruction system for reconstructing an image previously stored and displaying said reconstruction image on a display unit as a moving picture, said image reconstruction system comprising:

compression data memory means for storing compression data generated by dividing original video data constituting one screen page of video data into a plurality of pixel blocks and coding said video data on a block by block basis, each block consisting of an array of M by N pixels with M and N being integers greater than 2;

compression data input means for inputting said compression data stored in said compression data memory means, along a predetermined direction of an image;

decoding means for decoding said input compression data to video data corresponding to each said block, said decoding means including (i) at least two decoding elements using different decoding processes and (ii) decoding element activation means for selectively activating and using only a single one of said at least two decoding elements to decode said compression data based on information of a decoding process recorded in said compression data;

decoded data memory means for storing and arranging said decoded video data to make said decoded data readable in a unit of at least M lines when decoding of said compression data along said predetermined direction is completed, said unit of at least M lines corresponding to only a portion of said screen page;

reading means for successively reading said video data of at least M lines out of said decoded data memory means at a timing corresponding to a display timing of said display unit; and

reconstruction control means for controlling input of compression data by said compression data input means or data reading by said reading means according to information stored in said compression data memory means.