METHOD AND APPARATUS FOR ENCODING IMAGE DATA USING WAVELET SIGNATURES

• US 20160100194A1
• Filed: 10/09/2015
• Published: 04/07/2016
• Est. Priority Date: 08/26/2005
• Status: Active Grant

• Current Assignee: RGB Systems Incorporated
• Original Assignee: RGB Systems Incorporated
• Inventors: SMITH, PETER LIONEL
• Granted Patent: US 9,930,364 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/174 the region being a slice, e.g. a line of blocks or a group of blocks
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/1883 the unit relating to sub-band structure, e.g. hierarchical level, directional tree, e.g. low-high [LH], high-low [HL], high-high [HH]
• CPC Class Codes: H04N 19/33 in the spatial domain
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/507 using conditional replenishment
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/635 characterised by filter definition or implementation details
• CPC Class Codes: H04N 19/645 by grouping of coefficients into blocks after the transform
• CPC Class Codes: H04N 19/647 using significance based coding, e.g. Embedded Zerotrees of Wavelets [EZW] or Set Partitioning in Hierarchical Trees [SPIHT]
• CPC Class Codes: H04N 19/66 involving data partitioning, i.e. separation of data into packets or partitions according to importance
• CPC Class Codes: H04N 19/68 : involving the insertion of resynchronisation markers into the bitstream
• CPC Class Codes: H04N 19/70 : characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/86 : involving reduction of coding artifacts, e.g. of blockiness
• CPC Class Codes: H04N 19/89 : involving methods or arrangements for detection of transmission errors at the decoder
• CPC Class Codes: H04N 19/91 : Entropy coding, e.g. variable length coding [VLC] or arithmetic coding
• CPC Class Codes: H04N 19/96 : Tree coding, e.g. quad-tree coding

Abstract

Methods of data encoding using trees formed with logic gates are described which lead to spatial compression of image data. Data encoding is achieved using a five-level wavelet transform, such as the Haar or the 2/10 transform. A dual transform engine is used, the first and engine being used for the first part of the first-level transform, the second part of the first-level transform and the subsequent-level transforms being performed by the second transform engine within a time interval which is less than or equal to the time taken by the first transform engine to effect the part-transform. Each bit plane of the resulting coefficients is then encoded by forming a tree structure from the bits and OR logical combinations thereof. Redundant data are removed from the resulting tree structure, and further data can be removed by using a predetermined compression profile. The resulting blocks of compressed data are of variable length and are packaged with sync words and index words for transmission so that the location and identity of the transformed data blocks can be determined from the received signal.

Claims

1. A method of generating an output stream of image data from an input sequence of frames of image data by a codec, each of said frames of image data comprising a two-dimensional array of two-dimensional blocks of image data, said method comprising the steps of:

designating a first of said frames of image data and each nth subsequent as a reference frame, where n is an integer, each said reference frame separated from a next reference frame in said sequence of frames by a n−

1 intermediate frames;

comparing a plurality of said blocks of each of said intermediate frames to a corresponding plurality of blocks of an immediately preceding frame;

identifying corresponding blocks of said intermediate frame that differ according to a first criteria from said blocks of said immediately preceding frame;

including all of said blocks of said reference frames in said output stream;

including only said identified blocks of said intermediate frames in said output stream.

2. The method of claim 1 wherein said identifying step comprises:

determining a parameter for each of said blocks;

determining whether a value of said parameter for a block of said intermediate frame differs according to predetermined criteria from a corresponding block of said immediately preceding frame.

3. The method of claim 1 further comprising the step of designating an intermediate frame as an additional reference frame upon receipt of a demand signal.

4. The method of claim 1 further comprising the step of compressing said blocks included in said output stream.

5. The method of claim 2 wherein said blocks of said input sequence of frames of image data comprise blocks of YUV image data.

6. The method of claim 5 wherein said blocks of said input sequence of frames of image data comprise blocks of YUV image data transformed by a multi-level wavelet transform.

7. The method of claim 6 wherein said parameter is determined from a wavelet transformed Y component of said wavelet transformed YUV image data.

8. The method of claim 1 wherein n is predetermined.

9. The method of claim 7 wherein said step of determining said parameter comprises filtering said wavelet transformed Y component.

10. The method of claim 10 wherein said filtering comprises applying a noise threshold to said wavelet transformed Y component.

11. The method of claim 10 wherein said determining of said parameter comprises identifying a magnitude and position of a plurality of most significant wavelet coefficients of said filtered wavelet transformed Y component.

12. The method of claim 11 wherein said step of determining whether a value of said parameter for a block of said intermediate frame differs according to predetermined criteria from a corresponding block of said immediately preceding frame comprises comparing said magnitude and position of said plurality of most significant wavelet coefficients.

13. The method of claim 12 wherein said identifying said magnitude and position of said plurality of most significant wavelet coefficients comprises identifying a magnitude and position of a most significant wavelet coefficient in each of a plurality of sub-bands of said wavelet transformed Y component.

14. The method of claim 13 wherein said wavelet transform comprises a five-level transform and said sub-bands comprise 16 sub-bands.

15. The method of claim 13 wherein said step of comparing said magnitude and position of said plurality of said most significant wavelet coefficients comprises comparing said magnitude and position of a subset of said most significant wavelet coefficients.

16. The method of claim 15 wherein said subset of said most significant wavelet coefficients comprises a number of most significant of said most significant wavelet coefficients.

17. The method of claim 16 wherein said number of most significant of said most significant wavelet coefficients is predetermined.

18. The method of claim 16 wherein said number of most significant of said most significant wavelet coefficients is controllable via user input.

19. A method of compressing an input sequence of frames of image data by a codec, each of said frames of image data comprising a two-dimensional array of two-dimensional blocks of image data, said method comprising the steps of:

designating a first of said frames of image data and each nth subsequent as a reference frame, where n is an integer, each said reference frame separated from a next reference frame in said sequence of frames by a n−

1 intermediate frames;

comparing a plurality of said blocks of each of said intermediate frames to a corresponding plurality of blocks of an immediately preceding frame;

identifying corresponding blocks of said intermediate frame that differ according to a first criteria from said blocks of said immediately preceding frame;

compressing all of said blocks of said reference frames;

compressing only said identified blocks of said intermediate frames.

20. The method of claim 19 wherein said identifying step comprises:

determining a parameter for each of said blocks;

determining whether a value of said parameter for a block of said intermediate frame differs according to predetermined criteria from a corresponding block of said immediately preceding frame.