Dynamic bit allocation for three-dimensional subband video coding

• US 5,309,232 A
• Filed: 07/16/1993
• Issued: 05/03/1994
• Est. Priority Date: 02/07/1992
• Status: Expired due to Term

• Current Assignee: AT&T, Inc.
• Original Assignee: AT&T, Inc.
• Inventors: Hartung, John, Michel, Thomas A., Jacquin, Arnaud E., Podilchuk, Christine I.
• Primary Examiner(s): Brier, Jeffery
• Assistant Examiner(s): LIN, BRYAN T
• Application Number:
  US08/092,768
• Time in Patent Office: 291 Days
• Field of Search: 381/30, 381/31, 358/133
• US Class Current: 348/384.1
• CPC Class Codes: H04N 19/10 using adaptive coding
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• 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 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• 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 19/192 the adaptation method, adaptation tool or adaptation type being iterative or recursive
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/507 using conditional replenishment
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/62 by frequency transforming in three dimensions H04N19/63 takes precedence
• CPC Class Codes: H04N 19/63 : using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/94 : Vector quantisation

Abstract

The present invention provides a method of coding a set of multi-level signals, such as video signals. The method comprises filtering the set of multi-level signals into one or more sets of multi-level sub-band signals; allocating a first quantity of bits for use in coding a first set of sub-band signals; coding the first set of multi-level sub-band signals using zero or more of the first quantity of allocated bits; allocating a second quantity of bits for use in coding a second set of sub-band signals, the second quantity of bits comprising zero or more of the first quantity of bits not used in coding the first set of multi-level sub-band signals; and coding the second set of multi-level sub-band signals using zero or more of the second quantity of allocated bits. Three examples of the method are provided. A hardware implementation involving the use of digital signal processors operating in parallel is also provided.

Claims

1. A method of coding an image signal sequence, the image signal sequence comprising a plurality of image signals, an image signal comprising a set of pixel signals, the method comprising the steps of:

filtering the image signal sequence into a plurality of sets of sub-band pixel signals;

coding one or more pixel signals of a first set of sub-band pixel signals using one or more bits of a first quantity of bits, wherein each bit of the first quantity of bits is available for coding the first set of sub-band pixel signals;

providing a second quantity of bits for use in coding a second set of sub-band pixel signals, the second quantity of bits comprising one or more bits of the first quantity of bits not used in coding the first set of sub-band pixel signals; and

coding one or more pixel signals of the second set of sub-band pixel signals using one or more bits of the second quantity of bits.

2. The method of claim 1 further comprising the step of generating a first signal reflecting that one or more sub-band pixel signals of said first set may be represented by one or more previously decoded sub-band pixel signals.

3. The method of claim 2 wherein the generating step comprises the step of comparing one or more sub-band pixel signals with one or more previous sub-band pixel signals to determine whether a difference between the compared signals satisfies an error criterion.

4. The method of claim 3 wherein the error criterion is based on the sub-band corresponding to the compared sub-band pixel signals.

5. The method of claim 1 wherein the sub-band corresponding to the first set of sub-band pixel signals has a greater perceptual significance than the sub-band corresponding to the second set of sub-band pixel signals.

6. The method of claim 5 wherein the sub-band corresponding to the first set of sub-band pixel signals reflects low spatial frequencies of the set of pixel signals.

7. The method of claim 1 wherein the step of coding one or more pixel signals of the first set of sub-band pixel signals comprises the step of determining which one or more sub-band pixel signals of said first set are more perceptually significant relative to one or more other sub-band pixels of said first set.

8. An apparatus for coding an image signal sequence, the image signal sequence comprising a plurality of image signals, an image signal comprising a set of pixel signals, the apparatus comprising:

means for filtering the image signal sequence into a plurality of sets of sub-band pixel signals;

means for coding one or more pixel signals of a first set of sub-band pixel signals using one or more bits of a first quantity of bits, wherein each bit of the first quantity of bits is available for coding the first set of sub-band pixel signals;

means for providing a second quantity of bits for use in coding a second set of sub-band pixel signals, the second quantity of bits comprising one or more bits of the first quantity of bits not used in coding the first set of sub-band pixel signals; and

means for coding one or more pixel signals of the second set of sub-band pixel signals using one or more bits of the second quantity of bits.

9. The apparatus of claim 8 further comprising means for generating a first signal reflecting that one or more sub-band pixel signals may be represented by one or more previously decoded sub-band pixel signals.

10. The apparatus of claim 9 wherein the means for generating comprises means for comparing one or more sub-band pixel signals with one or more previous sub-band pixel signals to determine whether a difference between the compared signals satisfies an error criterion.

11. The apparatus of claim 10 wherein the error criterion is based on the sub-band corresponding to the compared sub-band pixel signals.

12. The apparatus of claim 8 wherein the sub-band corresponding to the first set of sub-band pixel signals has a greater perceptual significance than the sub-band corresponding to the second set of sub-band pixel signals.

13. The apparatus of claim 12 wherein the sub-band corresponding to the first set of sub-band pixel signals reflects low spatial frequencies of the set of pixel signals.

14. The apparatus of claim 8 wherein the means for coding one or more pixel signals of the first set of sub-band pixel signals comprises means for determining which one or more sub-band pixel signals of said first set are more perceptually significant relative to one or more other sub-band pixel signals of said first set.