Patent US5021891A successfully refreshed from Google Patents.
US5021891A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Adaptive block size image compression method and system
Assignee: Qualcomm Inc
•
Filing: 1990-02-27
•
Granted: 1991-06-04
•
Expires: 2010-02-27
Abstract
Abstract An image compression system and method for compressing image data for transmission. Each block and corresponding sub-blocks of pixel data is subjected to a discrete cosine transform (DCT) operation. Varying levels of sub-blocks of resulting corresponding transform coefficients are selected for construction into a composite transform coefficient block corresponding to each input block of pixel data. The selection of transform coefficient block size for the composite block is determined by a comparison process between transform block and sub-block coding efficiency. The composite block is variable length coded to further reduce bit count in the compressed data.
Inventors
- 👤 Chong U. Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:46
CPC Classifications
H; H04; H04N; H04N19/00; H04N1/00; H04N1/41; H04N1/411; H04N1/413; H04N1/415; G; G06; G06T; G06T9/00; G06T9/40; H04N19/10; H04N19/102; H04N19/119; H04N19/129; H04N19/134; H04N19/146; H04N19/15; H04N19/154; H04N19/169; H04N19/17; H04N19/172; H04N19/176; H04N19/18; H04N19/90; H04N19/96; H04N19/98; H04N19/13; H04N19/60; H04N19/91
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
228 words
In an image compression system, a sub-system for generating from a block of input pixel data a corresponding composite block of discrete cosine transform (DCT) data, comprising: transform means for, receiving an input block of pixel data, performing a discrete cosine transform (DCT) operation on said block of pixel data and on at least one predetermined level of constituent sub-blocks thereof, and providing corresponding block and sub-blocks of DCT coefficient values; block size assignment means for, receiving said block and each sub-block of DCT coefficient values, determining for each block and each corresponding group of sub-blocks of DCT coefficient values a bit count value corresponding to a number of bits required to respectively encode said block and each corresponding group of sub-blocks of DCT coefficient values according to a predetermined coding format, determining from said bit count values ones of said block and corresponding group of sub-blocks of DCT coefficient values requiring a lesser number of bits to encode according to said coding format, and providing a corresponding selection value; and selection means for, receiving said selection value and said block and each sub-block of DCT coefficient values, selecting ones of block and sub-blocks of DCT coefficients corresponding to said selection value, and providing an output of a corresponding composite block of DCT coefficient values formed from said selected ones of block and sub-blocks of DCT coefficient values.
Claim 2
Dependent Claim
228 words
In an image compression system, a sub-system for generating from a block of input pixel data a corresponding composite block of discrete cosine transform (DCT) data, comprising: transform means for, receiving an input block of pixel data, performing a discrete cosine transform (DCT) operation on said block of pixel data and on at least one predetermined level of constituent sub-blocks thereof, and providing corresponding block and sub-blocks of DCT coefficient values; block size assignment means for, receiving said block and each sub-block of DCT coefficient values, determining for each block and each corresponding group of sub-blocks of DCT coefficient values a bit count value corresponding to a number of bits required to respectively encode said block and each corresponding group of sub-blocks of DCT coefficient values according to a predetermined coding format, determining from said bit count values ones of said block and corresponding group of sub-blocks of DCT coefficient values requiring a lesser number of bits to encode according to said coding format, and providing a corresponding selection value; and selection means for, receiving said selection value and said block and each sub-block of DCT coefficient values, selecting ones of block and sub-blocks of DCT coefficients corresponding to said selection value, and providing an output of a corresponding composite block of DCT coefficient values formed from said selected ones of block and sub-blocks of DCT coefficient values.
Claim 3
Dependent Claim
62 words
The sub-system of claim 1 further comprising quantization means coupled between said transform means, said block size assignment means, and said selection means for, receiving said block and sub-blocks of DCT coefficient values, quantizing each DCT coefficient value, and providing each quantized DCT coefficient value to said block size assignment means and said selection means in place of a corresponding DCT coefficient.
Claim 4
Dependent Claim
330 words
An image signal compression system comprising: transform means for, receiving an input block of pixel data, performing a discrete cosine transform (DCT) operation on said block of pixel data and on at least one predetermined level of constituent sub-blocks thereof, and providing corresponding block and sub-blocks of DCT coefficient values; block size assignment means for, receiving said block and each sub-block of DCT coefficient values, determining for said block and each corresponding group of sub-blocks of DCT coefficient values a bit count value corresponding to a number of bits required to respectively encode said block and corresponding group of sub-blocks of DCT coefficient values according to a predetermined coding format, determining from said bit count values ones of said block and corresponding group of sub-blocks of DCT coefficient values requiring a lesser number of bits to encode according to said coding format, and providing a corresponding selection value; selection means for, receiving said selection value and said block and each sub-block of DCT coefficient values, selecting ones of block and sub-blocks of DCT coefficients corresponding to said selection value, and providing an output of a corresponding composite block of DCT coefficient values formed from said selected ones of block and sub-blocks of DCT coefficient values; ordering means for, receiving said composite block of DCT coefficient values, ordering said composite block DCT coefficient values according to a predetermined ordering format, and providing a corresponding output of ordered DCT coefficient values; encoder means for, receiving said ordered DCT coefficient values, coding said ordered DCT coefficient values according to said predetermined coding format, and providing corresponding coded values; and assembler means for, receiving said selection value and said coded values, combining said selection value and said coded value as a coded image value representative of said input block of pixel data with said coded image value of a reduced bit count with respect to a bit count of said input block of pixel data, and providing an output of said coded image value.
Claim 5
Dependent Claim
330 words
An image signal compression system comprising: transform means for, receiving an input block of pixel data, performing a discrete cosine transform (DCT) operation on said block of pixel data and on at least one predetermined level of constituent sub-blocks thereof, and providing corresponding block and sub-blocks of DCT coefficient values; block size assignment means for, receiving said block and each sub-block of DCT coefficient values, determining for said block and each corresponding group of sub-blocks of DCT coefficient values a bit count value corresponding to a number of bits required to respectively encode said block and corresponding group of sub-blocks of DCT coefficient values according to a predetermined coding format, determining from said bit count values ones of said block and corresponding group of sub-blocks of DCT coefficient values requiring a lesser number of bits to encode according to said coding format, and providing a corresponding selection value; selection means for, receiving said selection value and said block and each sub-block of DCT coefficient values, selecting ones of block and sub-blocks of DCT coefficients corresponding to said selection value, and providing an output of a corresponding composite block of DCT coefficient values formed from said selected ones of block and sub-blocks of DCT coefficient values; ordering means for, receiving said composite block of DCT coefficient values, ordering said composite block DCT coefficient values according to a predetermined ordering format, and providing a corresponding output of ordered DCT coefficient values; encoder means for, receiving said ordered DCT coefficient values, coding said ordered DCT coefficient values according to said predetermined coding format, and providing corresponding coded values; and assembler means for, receiving said selection value and said coded values, combining said selection value and said coded value as a coded image value representative of said input block of pixel data with said coded image value of a reduced bit count with respect to a bit count of said input block of pixel data, and providing an output of said coded image value.
Claim 6
Dependent Claim
47 words
The system of claim 3 further comprising: run-length coder means for, receiving said ordered DCT coefficient values, run-length coding said ordered coefficient values, and providing a corresponding output of non-zero coefficient values and run-length values to said encoder means for coding according to said predetermined coding format.
Claim 7
Independent Claim
293 words
A method for compressing an image signal corresponding to a block of pixel data, comprising the steps of: providing a block of pixel data capable of division into varying levels of constituent sub-blocks; performing a discrete cosine transform (DCT) operation on said block of pixel data so as to provide a corresponding block of DCT coefficients; performing a DCT operation on each sub-block of pixel data in at least one level of pixel data sub-blocks so as to provide corresponding sub-blocks of DCT coefficients; determining for each block and corresponding group of sub-blocks of DCT coefficients a bit count value corresponding to a number of bits necessary to encode each block and group of sub-blocks according to a predetermined coding format; determining, from said bit count values, ones of said block and corresponding groups of sub-blocks of DCT coefficients corresponding to a lower number of bits necessary to encode each block and corresponding group of sub-blocks of DCT coefficients so as to provide a corresponding block size assignment value; assembling, according to said block assignment value, a composite block of DCT coefficients from said ones of said block and corresponding groups of sub-blocks of DCT coefficients having a lower bit encoding number; ordering said composite block of DCT coefficients according to a predetermined ordering format so as to provide a serial string of ordered DCT coefficients; encoding said string of ordered DCT coefficients according to said predetermined coding format so as to provide a set of coded DCT coefficients; and assembling said block assignment value and said coded DCT coefficients into coded image data representative of said block of pixel data, said coded image data being of a reduced bit count with respect to a bit count of said block of pixel data.
Claim 8
Independent Claim
293 words
A method for compressing an image signal corresponding to a block of pixel data, comprising the steps of: providing a block of pixel data capable of division into varying levels of constituent sub-blocks; performing a discrete cosine transform (DCT) operation on said block of pixel data so as to provide a corresponding block of DCT coefficients; performing a DCT operation on each sub-block of pixel data in at least one level of pixel data sub-blocks so as to provide corresponding sub-blocks of DCT coefficients; determining for each block and corresponding group of sub-blocks of DCT coefficients a bit count value corresponding to a number of bits necessary to encode each block and group of sub-blocks according to a predetermined coding format; determining, from said bit count values, ones of said block and corresponding groups of sub-blocks of DCT coefficients corresponding to a lower number of bits necessary to encode each block and corresponding group of sub-blocks of DCT coefficients so as to provide a corresponding block size assignment value; assembling, according to said block assignment value, a composite block of DCT coefficients from said ones of said block and corresponding groups of sub-blocks of DCT coefficients having a lower bit encoding number; ordering said composite block of DCT coefficients according to a predetermined ordering format so as to provide a serial string of ordered DCT coefficients; encoding said string of ordered DCT coefficients according to said predetermined coding format so as to provide a set of coded DCT coefficients; and assembling said block assignment value and said coded DCT coefficients into coded image data representative of said block of pixel data, said coded image data being of a reduced bit count with respect to a bit count of said block of pixel data.
References Cited (Backward Citations)
US4179709A
Cited
US4293920A
Cited
US4504860A
Cited
US4807042A
Cited
US4774574A
Cited
US4924309A
Cited
US4922341A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-06-03 | 1994-12-03 | 1995-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-03 | 1998-12-03 | 1999-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-03 | 2002-12-03 | 2003-06-04 | $7700.00 | Window Closed / Lapsed |