Method for decoding a stream of coded data representative of a sequence of images and method for coding a sequence of images

• US 20110026844A1
• Filed: 07/30/2010
• Published: 02/03/2011
• Est. Priority Date: 07/30/2009
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Vieron, Jerome, Bordes, Philipe, Francois, Edouard, Thoreau, Dominique
• Granted Patent: US 8,520,960 B2
• Time in Patent Office: Days
• US Class Current: 382/233
• 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 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• 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 19/60 using transform coding
• CPC Class Codes: H04N 19/85 using pre-processing or post-processing specially adapted for video compression
• CPC Class Codes: H04N 19/88 involving rearrangement of data among different coding units, e.g. shuffling, interleaving, scrambling or permutation of pixel data or permutation of transform coefficient data among different blocks

Abstract

A method for decoding a stream of coded data representative of a sequence of images divided into blocks is described. It comprises the following steps for a current block:

• • reconstructing a residual block of residual data from the decoding of a first part of the coded stream of data relating to the current block,
  • determining a prediction block, and
  • reconstructing the current block by merging the residual block and the prediction block,
    According to the invention, the decoding method comprises in addition a step of reorganisation of residual data in the residual block before the reconstruction of the current block according to the content of the prediction block.
    The invention also relates to a method for coding.

Claims

1. A method for decoding a stream of coded data representative of a sequence of images divided into blocks comprising the following steps for a current block:

reconstructing a residual block of residual data from the decoding of a first part of the coded stream of data relating to the current block,

determining a prediction block,

reconstructing the current block by merging said residual block and said prediction block,

said method further comprises a step of reorganisation of residual data in said residual block before the reconstruction of said current block according to the content of said prediction block, wherein the step of reorganisation of residual data in said residual block comprises the following steps;

calculating, for at least two spatial directions, an energy level of spatial gradients of the prediction data, and

determining the reorganisation of residual data according to the spatial direction corresponding to the lowest energy level.

2. A method for decoding according to claim 1, wherein the step of reconstruction of said residual block comprises the following steps:

decoding said first part of the stream of coded data (F) into a block of decoded coefficients according to a scanning order of said block of decoded coefficients determined according to the content of said prediction block,

dequantizing the block of decoded coefficients into a block of dequantized coefficients, and

transforming said block of dequantized coefficients into the residual block.

3. A method for decoding according to claim 2, wherein the scanning order is determined according to the following steps:

applying a high pass filter on the prediction block,

reorganising the data in said filtered prediction block in the same way as the residual data in said residual block,

transforming said filtered and reorganised prediction block into a block of coefficients,

determining the scanning order in such a way as to scan said coefficients in descending order of value.

4. A method for decoding according to claim 1, wherein the energy level of spatial gradients is calculated for a given spatial direction d according to the following equation:

5. A method for decoding according to claim 1, wherein the step of reorganisation of residual data in said residual block also comprises a step of calculation of an additional energy level from the energy levels of spatial gradients calculated in at least two spatial directions.

6. A method for coding a sequence of images divided into blocks comprising the following steps for a current block:

determining a prediction block for said current block,

determining a residual block of residual data by extracting from said current block said prediction block,

coding said residual block,

said method further comprises a step of reorganisation of residual data in said residual block before its coding according to the content of said prediction block, wherein the step of reorganisation of residual data in said residual block comprises the following steps;

calculating, for at least two spatial directions, an energy level of spatial gradients of the prediction data, and

determining the reorganisation of residual data according to the spatial direction corresponding to the lowest energy level.

7. A method for coding according to claim 6, wherein the step of coding of said residual block comprises the following steps:

transforming said residual block into a block of coefficients,

quantizing said block of coefficients into a block of quantized coefficients, and

coding said quantized coefficients according to a scanning order of said block of quantized coefficients determined according to the content of said prediction block.

8. A method for coding according to claim 7, wherein the scanning order is determined according to the following steps:

applying a high pass filter on the prediction block,

reorganising the data in said filtered prediction block in the same way as the residual data in said residual block,

transforming said filtered and reorganised prediction block into a block of coefficients,

determining the scanning order in such a way as to scan said coefficients in descending order of value.