Method and apparatus for clipping coefficient values after application of each wavelet transform

• US 6,898,325 B2
• Filed: 03/06/2001
• Issued: 05/24/2005
• Est. Priority Date: 02/15/2001
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Gormish, Michael J.
• Primary Examiner(s): Chen, Wenpeng
• Application Number:
  US09/801,361
• Publication Number:
  US 20030206661A1
• Time in Patent Office: 1,540 Days
• Field of Search: 382/239, 382/248, 382/302, 382/232, 382/240, 382/243, 382/250, 375/240.11, 375/240.19, 375/240.1, 375/240.08, 375/240.01, 375/240.18
• US Class Current: 382/248
• CPC Class Codes: G11B 27/036 Insert-editing
• 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 19/124 Quantisation
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/129 Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/34 Scalability techniques involving progressive bit-plane based encoding of the enhancement layer, e.g. fine granular scalability [FGS]
• CPC Class Codes: H04N 19/36 Scalability techniques involving formatting the layers as a function of picture distortion after decoding, e.g. signal-to-noise [SNR] scalability
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• 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 19/426 : using memory downsizing methods
• CPC Class Codes: H04N 19/45 : performing compensation of the inverse transform mismatch, e.g. Inverse Discrete Cosine Transform [IDCT] mismatch
• 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 19/593 : involving spatial prediction techniques
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 19/619 : the transform being operated outside the prediction loop
• 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 19/64 : characterised by ordering of coefficients or of bits for transmission
• 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 19/70 : characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/85 : using pre-processing or post-processing specially adapted for video compression
• CPC Class Codes: H04N 19/86 : involving reduction of coding artifacts, e.g. of blockiness

Abstract

A method and apparatus for clipping coefficient values after application of each wavelet transform is described. In one embodiment, the method comprises applying an inverse wavelet transform to data repeatedly for a plurality of decomposition levels, and clipping, after each application of the inverse wavelet transform, any value generated as a result of application of the inverse wavelet transform that exceeds a predetermined range associated with that decomposition level subband of the inverse wavelet transform.

Claims

1. A method comprising:

applying an inverse wavelet transform having a 5,3 wavelet transform filter to data repeatedly for a plurality of decomposition levels during quantization of wavelet coefficients that is performed using a plurality of stages including one or more intermediate stages and a final stage; and

for each of the plurality of decomposition levels, clipping, after each application of the inverse wavelet transform during the one or more intermediate stages prior to the final stage, any value generated as a result of application of the inverse wavelet transform that exceeds a predetermined range associated with that decomposition level subband of the inverse wavelet transform including, after the inverse wavelet transform for 8-bit input samples, clipping low-pass coefficients exceeding the respective predetermined range to a value ranging from approximately −

191 to 191.

2. The method defined in claim 1 wherein the inverse wavelet transform comprises a 9,7 wavelet transform filter.

3. The method defined in claim 1, wherein each of the plurality of decomposition levels has a predetermined range of values for clipping data after application of a wavelet transform at the respective decomposition level, at least two of the decomposition levels having different predetermined ranges.

4. The method defined in claim 1, further comprising clipping high-pass coefficients exceeding the respective predetermined range to a value ranging from approximately −

255 to 255.

5. An article of manufacture comprising one or more recordable media having executable instructions stored thereon which, when executed by a machine, cause the machine to:

apply an inverse wavelet transform having a 5,3 wavelet transform filter to data repeatedly for a plurality of decomposition levels during quantization of wavelet coefficients that is performed using a plurality of stages including one or more intermediate stages and a final stage; and

for each of the plurality of decomposition levels, clip, after each application of the inverse wavelet transform during the one or more intermediate stages prior to the final stage, any value generated as a result of application of the inverse wavelet transform that exceeds a predetermined range associated with that decomposition level, subband and inverse wavelet transform including, after the inverse wavelet transform for 8-bit input samples, clipping low-pass coefficients exceeding the respective predetermined range to a value ranging from approximately −

191 to 191.

6. The article of manufacture defined in claim 5 wherein the inverse wavelet transform comprises a 9,7 wavelet transform filter.

7. The article of manufacture defined in claim 5, wherein each of the plurality of decomposition levels has a predetermined range of values for clipping data after application of a wavelet transform at the respective decomposition level, at least two of the decomposition levels having different predetermined ranges.

8. The article of manufacture defined in claim 5, wherein the instructions further cause the machine to clip high-pass coefficients exceeding the respective predetermined range to a value ranging from approximately −

255 to 255.

9. An apparatus comprising:

means for applying an inverse wavelet transform having a 5,3 wavelet transform filter to data repeatedly for a plurality of decomposition levels during quantization of wavelet coefficients that is performed using a plurality of stages including one or more intermediate stages and a final stage; and

for each of the plurality of decomposition levels, means for clipping, after each application of the inverse wavelet transform during the one or more intermediate stages prior to the final stage, any value generated as a result of application of the inverse wavelet transform that exceeds a predetermined range associated with that decomposition level, subband and inverse wavelet transform including, after the inverse wavelet transform for 8-bit input samples, means for clipping low-pass coefficients exceeding the respective predetermined range to a value ranging from approximately −

191 to 191.

10. The apparatus defined in claim 9 wherein the inverse wavelet transform comprises a 9,7 wavelet transform filter.

11. The apparatus defined in claim 9, wherein each of the plurality of decomposition levels has a predetennined range of values for clipping data after application of a wavelet transform at the respective decomposition level, at least two of the decomposition levels having different predetermined ranges.

12. The apparatus defined in claim 9, further comprising means for clipping a high-pass coefficients exceeding the respective predetermined range to a value ranging from approximately −

255 to 255.