Methods and devices for coding and decoding a data stream representing at least one image

A method comprising:

• encoding, by an encoding device, at least one image in the form of a stream of encoded data, said image being subdivided into blocks, at least two prediction modes being available to predict a block of said image, called a current block, the encoding comprising the following steps, for said current block:
• for each prediction mode available for predicting said current block, obtaining a predictive block associated with the available prediction mode,
• building a list comprising at least one of the at least two available prediction modes,
• for each prediction mode included in said list, called a current mode:
• determining measurements of distance between the predictive block associated with said current mode and each of the other predictive blocks associated with the other available prediction modes and obtained for said current block,
• modifying said list as a function of said determined measurements of distance including removing said current mode from said list when the determined measurement of distance indicates that the predictive block associated with said current mode comprised in the list is similar to a predictive block associated with another available prediction mode, or re-ordering the list in descending order of the measurement of distances determined for each prediction mode of the list,
• selecting, from the modified list, a prediction mode to encode the current block, and
• encoding, in the stream of encoded data, a piece of information identifying, for said current block, said prediction mode selected in the modified list.

A decoding device comprising:

• a processor;
• and
• a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the decoding device to perform acts comprising:
• decoding an encoded data stream representing at least one image, said image being subdivided into blocks, at least two prediction modes being available to predict a block, called a current block, of the image, the decoding comprising for said current block:
• obtaining, for each prediction mode available for predicting said current block, a predictive block associated with the available prediction mode,
• building a list comprising at least one of the at least two available prediction modes,
• for each prediction mode included in said list, called a current mode:
• determining measurements of distance between the predictive block associated with said current mode and each of the other predictive blocks associated with the other available prediction modes and obtained for said current block,
• modifying said list as a function of said determined measurements of distance including removing said current mode from said list when the determined measurement of distance indicates that the predictive block associated with said current mode comprised in the list is similar to a predictive block associated with another available prediction mode, or re-ordering the list in descending order of the measurement of distances determined for each prediction mode of the list,
• decoding, from the stream of encoded blocks, a piece of information identifying, for said current block, a prediction mode from the modified list, and
• rebuilding said current block from the predictive block associated with said identified prediction mode.

An encoding device comprising:

• a processor;
• and
• a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the encoding device to perform acts comprising:
• encoding at least one image in the form of a stream of encoded data, said image being subdivided into blocks, at least two prediction modes being available to predict a block of said image, called a current block, the encoding comprising, for said current block:
• obtaining, for each prediction mode available for predicting said current block, a predictive block associated with the available prediction mode,
• building a list comprising one of the at least two available prediction modes,
• for each prediction mode included in said list, called a current mode:
• determining measurements of distance between the predictive block associated with said current mode and each of the other predictive blocks associated with the other available prediction modes and obtained for said current block,
• modifying said list as a function of said determined measurements of distance including removing said current mode from said list when the determined measurement of distance indicates that the predictive block associated with said current mode comprised in the list is similar to a predictive block associated with another available prediction mode, or re-ordering the list in descending order of the measurement of distances determined for each prediction mode of the list,
• selecting, from the modified list, a prediction mode to encode the current block, and
• encoding, in the stream of encoded data, a piece of information identifying, for said current block, said prediction mode selected in the modified list.

A non-transitory computer-readable medium comprising instructions stored thereon, which when executed by a processor of a decoding device configure the decoding device to perform acts comprising:

• decoding by the decoding device an encoded data stream representing at least one image, said image being subdivided into blocks, at least two prediction modes being available to predict a block, called a current block, of the image, the decoding comprising, for said current block, the following steps:
• for each prediction mode available for predicting said current block, obtaining a predictive block associated with the available prediction mode,
• building a list comprising at least one of the at least two available prediction modes,
• for each prediction mode included in said list, called a current mode:
• determining measurements of distance between the predictive block associated with said current mode and each of the other predictive blocks associated with the other available prediction modes and obtained for said current block,
• modifying said list as a function of said determined measurements of distance including removing said current mode from said list when the determined measurement of distance indicates that the predictive block associated with said current mode comprised in the list is similar to a predictive block associated with another available prediction mode, or re-ordering the list in descending order of the measurement of distances determined for each prediction mode of the list,
• decoding, from the stream of encoded blocks, a piece of information identifying, for said current block, a prediction mode from the modified list, and
• rebuilding said current block from the predictive block associated with said identified prediction mode.

A non-transitory computer-readable medium comprising instructions stored thereon, which when executed by a processor of an encoding device configure the encoding device to perform acts comprising:

• encoding at least one image in the form of a stream of encoded data, said image being subdivided into blocks, at least two prediction modes being available to predict a block of said image, called a current block, the encoding comprising the following steps, for said current block:
• for each prediction mode available for predicting said current block, obtaining a predictive block associated with the available prediction mode,
• building a list comprising at least one of the at least two available prediction modes,
• for each prediction mode included in said list, called a current mode:
• determining measurements of distance between the predictive block associated with said current mode and each of the other predictive blocks associated with the other available prediction modes and obtained for said current block,
• modifying said list as a function of said determined measurements of distance including removing said current mode from said list when the determined measurement of distance indicates that the predictive block associated with said current mode comprised in the list is similar to a predictive block associated with another available prediction mode, or re-ordering the list in descending order of the measurement of distances determined for each prediction mode of the list,
• selecting, from the modified list, a prediction mode to encode the current block, and
• encoding, in the stream of encoded data, a piece of information identifying, for said current block, said prediction mode selected in the modified list.