Context generation

• US 7,054,493 B2
• Filed: 01/08/2003
• Issued: 05/30/2006
• Est. Priority Date: 09/21/1994
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Schwartz, Edward L.
• Primary Examiner(s): Tran, Phuoc
• Application Number:
  US10/339,543
• Publication Number:
  US 20030142874A1
• Time in Patent Office: 1,238 Days
• Field of Search: 382/232, 382/238, 382/240, 382/244, 382/246, 382/248, 358/426.13, 341/67, 341/107, 375/240.19
• US Class Current: 382/232
• CPC Class Codes: G06F 17/148 Wavelet transforms
• CPC Class Codes: G06K 15/02 using printers
• CPC Class Codes: G06K 15/1865 by compressing the rasterized print data
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction
• CPC Class Codes: H04N 19/10 using adaptive coding
• CPC Class Codes: H04N 19/102 characterised by the element, parameter or selection affected or controlled by the adaptive coding
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/12 Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
• CPC Class Codes: H04N 19/122 Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
• CPC Class Codes: H04N 19/124 Quantisation
• 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 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• 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 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/156 Availability of hardware or computational resources, e.g. encoding based on power-saving criteria
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/167 Position within a video image, e.g. region of interest [ROI]
• 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 19/184 : the unit being bits, e.g. of the compressed video stream
• 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 19/36 : 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 19/42 : 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 19/46 : 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 19/60 : using transform coding
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 19/635 : characterised by filter definition or implementation details
• 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 19/98 : Adaptive-dynamic-range coding [ADRC]
• CPC Class Codes: H04N 21/6377 : directed to server one-way streaming services wherein the source is controlled by the destination H04L65/613
• CPC Class Codes: H04N 21/658 : Transmission by the client directed to the server

Abstract

A method and apparatus for performing compression and/or decompression is described. In one embodiment, the present invention comprises a system having a buffer, a wavelet transform unit, and a coder. The wavelet transform unit has an input coupled to the buffer to perform a wavelet transform on pixels stored therein and to generate coefficients at an output. The coder is coupled to the wavelet transform unit to code the transformed pixels received from the buffer.

Claims

1. A context model for generating a context, the context model comprising:

a first input for information indicative of a current bitplane for which contexts are to be generated;

a second input of coefficients from a memory;

a unit coupled to the first and second inputs to determine whether a one bit in the coefficient bits being input and identifies the location of the one bit if located, the unit having an output indicative of whether a first non-zero magnitude bit has been observed and the bit plane in which it was observed, if so;

a plurality of registers coupled to the unit and to receive bits of coefficients from the memory to store data corresponding to neighboring coefficients that comprise coefficients above, below and to the left of a current coefficient for which a context is being generated, wherein outputs of the plurality of registers form the context based on the data corresponding to neighboring coefficients and based on the outputs of the unit.

2. The context model defined in claim 1 wherein the plurality of registers comprise shift registers.

3. The context model defined in claim 1 wherein one of the plurality of registers outputs a bit of information along with the context.

4. The context model defined in claim 1 wherein at least one of the plurality of registers stores one or more parent coefficients used to form the context.

5. The context model defined in claim 1 wherein a first of the plurality of registers stores coefficient data from coefficients above and to the left of the current coefficient, a second of the plurality of registers stores coefficient data from coefficients below and to the right of the current coefficient and a third of the plurality of registers stores the current coefficient.

6. An apparatus comprising:

a reversible wavelet filter to transform input data into a plurality of coefficients;

an order unit to generate an embedded codestream using the plurality of coefficients;

a context model for generating contexts, the context model comprising

a first input for information indicative of a current bitplane for which contexts are to be generated,

a second input of coefficients from a memory,

a unit coupled to the first and second inputs to determine whether a one bit in the coefficient bits being input and identifies the location of the one bit if located, the unit having an output indicative of whether a first non-zero magnitude bit has been observed and the bit plane in which it was observed, if so,

a plurality of registers coupled to the unit and to receive bits of coefficients from the memory to store data corresponding to neighboring coefficients that comprise coefficients above, below and to the left of a current coefficient for which a context is being generated, wherein outputs of the plurality of registers form the context based on the data corresponding to neighboring coefficients and based on the outputs of the unit; and

a binary entropy coder coupled to the context model to code the embedded codestream to generate a compressed data stream based on contexts from the context model.

7. The apparatus defined in claim 6 wherein the plurality of registers comprise shift registers.

8. The apparatus defined in claim 6 wherein one of the plurality of registers outputs a bit of information along with the context.

9. The apparatus defined in claim 6 wherein at least one of the plurality of registers stores one or more parent coefficients used to form the context.

10. The apparatus defined in claim 6 wherein a first of the plurality of registers stores coefficient data from coefficients above and to the left of the current coefficient, a second of the plurality of registers stores coefficient data from coefficients below and to the right of the current coefficient and a third of the plurality of registers stores the current coefficient.