Method for intra-coding of a digital image and corresponding decoding method

A method comprising the following acts performed by a coding device:

• coding an image in the form of a stream of coded data, said image being divided into blocks, a set of at least two prediction modes being available for predicting a current block of the blocks of the image, wherein the coding comprises the following steps:
• obtaining at least two categories of prediction modes from the set, similarly to a stream coder;
• eliminating at least one category in accordance with at least one first predetermined elimination criterion;
• updating the categories not eliminated by deleting prediction modes which are common with said at least one eliminated category;
• selecting a prediction mode in one of the updated categories;
• and
• coding an information identifying the prediction mode selected from the updated category prediction modes, and inserting the coded information into the coded data stream;
• and
• transmitting the coded data stream over a communication network.

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:
• receiving from a communication network a coded data stream representative of at least one image, said image being cut into blocks;
• and
• decoding the coded data stream, a set of at least two prediction modes being available for predicting a current block of the blocks of the image, wherein the decoding comprises:
• obtaining at least two categories of prediction modes from the set, similarly to a stream coder;
• eliminating at least one category in accordance with at least one first predetermined elimination criterion;
• updating the categories not eliminated by deleting prediction modes which are common with said at least one eliminated category;
• and
• decoding, from the data stream, an information identifying for the current block a prediction mode among the modes of the updated categories.

A coding device comprising:

• a processor;
• and
• a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the coding device to perform acts comprising:
• coding an image in the form of a coded data stream, said image being divided into blocks, a set of at least two prediction modes being available for predicting a current block of the blocks of the image, wherein the coding comprises:
• obtaining at least two categories of prediction modes from the set, similarly to a stream decoder;
• eliminating at least one category in accordance with at least one first predetermined elimination criterion;
• updating the categories not eliminated by deleting prediction modes which are common with said at least one eliminated category;
• selecting a prediction mode in one of the updated categories;
• and
• coding an information identifying the prediction mode selected from the updated category prediction modes, and inserting the coded information into the coded data stream;
• and
• transmitting the coded data stream over a communication network.

A non-transitory computer-readable medium comprising a computer program stored thereon, which comprises instructions for implementing a decoding method, when executed by a processor of a decoding device, wherein the decoding method comprises:

• receiving from a communication network a coded data stream representative of at least one image, said image being divided into blocks;
• and
• decoding the coded data stream, a set of at least two prediction modes being available for predicting a current block of the blocks of the image, wherein the decoding comprises the following steps:
• obtaining at least two categories of prediction modes from the initial set, similarly to a stream coder;
• eliminating at least one category based on at least one first predetermined elimination criterion;
• updating the categories not eliminated by deleting prediction modes which are common with said at least one eliminated category;
• and
• decoding, from the data stream, an information identifying for the current block a prediction mode among the modes of the updated categories.

A non-transitory computer-readable medium comprising a computer program stored thereon, which comprises instructions for implementing a coding method, when executed by a processor of a coding device, wherein the coding method comprises:

• coding an image in the form of a stream of coded data, said image being divided into blocks, a set of at least two prediction modes being available for predicting a current block of the blocks of the image, wherein the coding comprises the following steps:
• obtaining at least two categories of prediction modes from the set, similarly to a stream coder;
• eliminating at least one category in accordance with at least one first predetermined elimination criterion;
• updating the categories not eliminated by deleting prediction modes which are common with said at least one eliminated category;
• selecting a prediction mode in one of the updated categories;
• and
• coding an information identifying the prediction mode selected from the updated category prediction modes, and inserting the coded information into the coded data stream;
• and
• transmitting the coded data stream over a communication network.