METHOD FOR DECODING AN IMAGE, ENCODING METHOD, DEVICES, TERMINAL EQUIPMENT AND ASSOCIATED COMPUTER PROGRAMS

• US 20200137393A1
• Filed: 06/12/2018
• Published: 04/30/2020
• Est. Priority Date: 06/29/2017
• Status: Active Grant

• Current Assignee: BCom, Fondation B-Com
• Original Assignee: BCom
• Inventors: Henry, Felix
• Granted Patent: US 11,323,715 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04N 19/119 Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
• 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 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/176 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 19/192 the adaptation method, adaptation tool or adaptation type being iterative or recursive
• CPC Class Codes: H04N 19/463 by compressing encoding parameters before transmission
• CPC Class Codes: H04N 19/50 using predictive coding H04N19/61 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/64 characterised by ordering of coefficients or of bits for transmission
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

A method for decoding an encoded data stream representative of at least one image, which is divided into blocks. The decoding method includes, for a current block: evaluating a plurality of value hypotheses of at least one description element of the current block, by calculating a likelihood measurement per hypothesis; calculating a disparity in the likelihood measurements obtained; determining at least one parameter of a decoder based on the calculated disparity; decoding, using the determined decoder, complementary information for identifying at least one of the hypotheses; and identifying at least one of the hypotheses using the decoded complementary information and obtaining a value of the at least one description element for the current block, from the at least one identified hypothesis.

Claims

1. A method for decoding an encoded data stream representative of at least one image, said image being divided into blocks, wherein the decoding method comprises, for a current block, the following acts performed by a decoding device:

evaluating a plurality of value hypotheses of at least one description element of the current block, by calculating a likelihood measurement per hypothesis, said calculation being a same calculation as that used to encode the data bitstream;

calculating a disparity of the obtained likelihood measurements;

determining at least one parameter of an entropic decoder as a function of the calculated disparity, said at least one parameter belonging to a group comprising at least;

a parameter comprising a context associated with an adaptive binary arithmetic decoder;

a parameter comprising a probability associated with a complementary information for identifying at least one of these hypotheses;

a parameter comprising an identifier of a predetermined decoder;

decoding, using an entropic decoder configured by said at least one parameter, the complementary information for identifying at least one of said hypotheses; and

identifying at least one of the hypotheses using at least the decoded complementary information and obtaining a value of said at least one description element for the current block, from said at least one identified hypothesis.

3. The method according to claim 1, further comprising classifying hypotheses in decreasing likelihood order, wherein the complementary information includes a rank in the classification and the value of said at least one description element corresponds to the hypothesis classified in said rank.

4. The method according to claim 1, further comprising predicting the value of said at least one description element by selecting the value hypothesis associated with the highest likelihood measurement, referred to as a predicted value, and wherein the complementary information comprises a difference between the predicted value and the value of the description element, said residual value.

5. the method according to claim 3, wherein the evaluating comprises evaluating a plurality of hypotheses of a sequence of at least two description elements, wherein for the first element of the sequence, the calculating comprises calculating a disparity of the likelihood measurements obtained for the plurality of hypotheses of the sequence and wherein the value of the first description element of the sequence matches that of the identified hypothesis.

11. The method according to claim 1, further comprising the decoding device receiving the current block from a communication network or a non-transitory computer-readable medium.

14. The method according to claim 3, further comprising predicting the value of said at least one description element by selecting the value hypothesis associated with the highest likelihood measurement, referred to as a predicted value, and wherein the complementary information comprises a difference between the predicted value and the value of the description element, said residual value.

15. The method according to claim 4, wherein the evaluating comprises evaluating a plurality of hypotheses of a sequence of at least two description elements, wherein for the first element of the sequence, the calculating comprises calculating a disparity of the likelihood measurements obtained for the plurality of hypotheses of the sequence and wherein the value of the first description element of the sequence matches that of the identified hypothesis.

2. A method for encoding a data stream representative of at least one image, said image being divided into blocks, wherein the method comprises the following acts, implemented for a current block by an encoding device:

evaluating a plurality of value hypotheses of at least one description element of the current block, by calculation of a likelihood measurement per hypothesis;

calculating a disparity of the obtained likelihood measurements;

determining at least one parameter of an entropic encoder according to the calculated disparity, said at least one parameter belonging to a group comprising at least;

a parameter comprising a context associated with an adaptive binary arithmetic encoder;

a parameter comprising a probability associated with complementary information for identifying at least one of said hypotheses;

a parameter comprising an identifier of a predetermined encoder;

encoding said complementary information using an entropic encoder configured by said at least one parameter; and

inserting the encoded information into the stream.

12. The method according to claim 2, further comprising the encoding device transmitting the stream on a communication network or store the stream in a non-transitory computer-readable medium.

13. The method according to claim 2, further comprising classifying hypotheses in decreasing likelihood order, wherein the complementary information includes a rank in the classification and the value of said at least one description element corresponds to the hypothesis classified in said rank.

6. A device for decoding an encoded data stream representative of at least one image, said image being divided into blocks, wherein the device comprises a computing machine configured for or dedicated to:

for the a current block;

evaluating a plurality of value hypotheses of at least one description element of the current block, by calculating a likelihood measurement by hypothesis;

calculating a disparity of the obtained likelihood measurements;

determining at least one parameter of an entropic decoder according to the calculated disparity, said at least one parameter belonging to a group comprising at least;

a parameter comprising a context associated with an adaptive binary arithmetic decoder;

a parameter comprising a probability associated with complementary information of at least one of said hypotheses;

a parameter comprising an identifier of a predetermined decoder;

decoding using an entropic decoder configured by said at least one parameter the complementary information for identifying of at least one of said hypotheses; and

identifying at least one of the hypotheses using at least the decoded complementary information and obtaining the value of said at least one description element for the current block, from said at least one identified hypothesis.

8. The device according to claim 6, wherein the device is implemented in a terminal equipment for a communication network.

16. The device according to claim 6, wherein the computing machine is configured for or dedicated to receive the current block from a communication network or a non-transitory computer-readable medium.

7. A device for encoding a data stream representative of at least one image, said image being divided into blocks, wherein the device comprises a computing machine configured for or dedicated to:

for the current block;

evaluate a plurality of value hypotheses of at least one description element of the current block, by calculating a likelihood measurement per hypothesis;

calculate a disparity of the obtained likelihood measurements;

determine at least one parameter of an entropic encoder as a function of the calculated disparity, said at least one parameter belonging to a group comprising at least;

a parameter comprising a context associated with an adaptive binary arithmetic encoder;

a parameter comprising a probability associated with complementary information identifying at least one of said hypotheses;

a parameter comprising an identifier of a predetermined encoder;

encoding using an entropic encoder configured by said at least one parameter the complementary information for identifying at least one of said hypotheses; and

insert the encoded information into the bitstream.

17. The device according to claim 7, wherein the computing machine is configured for or dedicated to transmit the stream on a communication network or store the stream in a non-transitory computer-readable medium.

18. The device according to claim 7, wherein the device is implemented in a terminal equipment for a communication network.

9. (canceled)

10. (canceled)