Method for encoding and/or decoding groups of images

• US 7,864,863 B2
• Filed: 05/01/2004
• Issued: 01/04/2011
• Est. Priority Date: 05/23/2003
• Status: Expired due to Fees

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Boisson, Guillaume, Francois, Edouard, Thoreau, Dominique
• Primary Examiner(s): Dang; Duy M
• Application Number:
  US10/558,140
• Publication Number:
  US 20060233256A1
• Time in Patent Office: 2,439 Days
• Field of Search: 382232-252, 37524002-24029
• US Class Current: 375/240.19
• 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

Abstract

The present invention relates to a method of coding and/or decoding groups of pictures. According to the invention, during the temporal decomposition of a stream of pictures within the framework of 3D wavelet processing, the number of pictures, the choice of the reference picture and the direction of temporal decomposition for each picture sequence of GOP type are adapted in order to minimize the number of unconnected pixels.

Claims

1. Method of coding picture sequences using a coding device, based on a 3D wavelet coding, including a coding phase which comprises:

a step for determining at least one information item for configuring the 3D wavelet coding as a selection of a reference picture for a sequence of successive pictures, based on a predetermined optimizing criterion;

then

a step for generating a configuration information unit comprising a datum of the reference picture for the said sequence of successive pictures; and

finally

a step for executing the 3D wavelet coding based on the configuration information to give 3D wavelet coding data,

in such a way as to produce a stream of coded data comprising the union for each sequence of pictures of a configuration information unit and of the 3D wavelet coding data for the pictures of the picture sequence.

2. Method according to claim 1, wherein the step for determining at least one configuration information item comprises a step of wavelet decomposition in at least one test picture as reference picture, then a step of motion estimation, then a step of determining the picture of the picture sequence for which the number of unconnected pixels during the motion estimation step is a minimum, as reference picture.

3. Method according to claim 1, wherein the step for determining at least one configuration information item comprises a step of determining the amplitude of the motion in at least one test picture, then a step of determining the picture of the picture sequence for which the amplitude of motion in the picture is a minimum, as reference picture.

4. Method according to claim 1, wherein the step for determining at least one configuration information item comprises a step of determining a texture information item, by measuring the high frequency components, in at least one test picture, then a step of determining the picture of the picture sequence for which the texture information item is the richest, as reference picture.

5. Method according to claim 1, wherein the step for determining at least one configuration information item also comprises the determination of the number of pictures in the said picture sequence.

6. Method according to claim 1, wherein the step for determining at least one configuration information item also comprises the determination of at least one direction of temporal decomposition for a picture sequence.

7. Method according to claim 1, wherein the step for determining at least one configuration information item consists:

in a first step;

in constructing picture sequences GOP of a predetermined size,

in a second step;

for each picture sequence, in selecting the first picture of the picture sequence as reference picture and a direction of temporal decomposition in the forward direction or the last picture of the picture sequence as reference picture and a direction of temporal decomposition in the backward direction according to the choice which minimizes the number of unconnected pixels.

8. Method according to claim 1, wherein the step for determining at least one configuration information item consists:

in a first step;

in constructing a GOP picture sequence of a predetermined size,

in a second step;

in executing the choice of a reference picture,

and in that the direction of temporal decomposition is determined in the forward direction for the pictures of the picture sequence which follow the selected reference picture and in the backward direction for the pictures of the picture sequence which precede the selected reference picture.

9. Method according to claim 8, wherein the step for determining at least one configuration information item comprises:

in the forward direction between pictures;

a step of estimating the motion, a step of constructing the trajectories of the motion dots in the forward motion estimation and a step of computing the number of unconnected pixels during the step of constructing the trajectories;

in the backward direction between pictures;

a step of estimating the motion in the backward direction between pictures, a step of constructing the trajectories of the motion dots in the forward motion estimation and a step of computing the number of unconnected pixels during the step of constructing the trajectories;

a step of choosing the best reference picture on the basis of the smallest number of unconnected pixels.

10. Method according to claim 1, wherein the step for determining at least one configuration information item comprises:

a step of estimating the motion in the forward direction between pictures and concurrently with a step of estimating the motion in the backward direction between pictures;

then

a loop is performed for each picture of the GOP sequence undergoing adaptation in the course of which successively a step of constructing the trajectories is executed, then a step of computing the number of unconnected pixels;

then

a step of selecting the best reference picture in the GOP picture sequence undergoing adaptation is performed on the basis of the smallest number of unconnected points.

11. Method of decoding picture sequences coded according to the method of claim 1, using a decoding device comprising a 3D wavelet decoding circuit, comprising a decoding phase which consists:

in decoding a configuration information unit determining characteristics of the 3D wavelet coding performed on a given stream of binary data;

then

in performing an updating of the 3D wavelet decoding circuit; and

finally

in performing a decoding of the stream of binary data representative of a picture sequence, using the 3D wavelet decoding circuit, so as to produce at output at least one sequence of pictures contained in the given stream of binary data.

12. Method according to claim 11, integrated into a 3D wavelet-based video decompressor scheme.

13. Method according to claim 11, integrated into an MPEG™

decoding scheme.

14. Method according to claim 1, integrated into a 3D wavelet-based video compressor scheme.

15. Method according to claim 1, integrated into an MPEG™

coding scheme.