Method for decoding a digital image, coding method, devices, terminal and associated computer programs

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

• coding a coded data stream representative of at least one image, said image being divided into blocks, wherein coding comprises:
• the following acts, implemented for a current block:
• encoding the current block into a plurality of encoded data;
• extracting the plurality of encoded data from a first sequence comprising a predetermined non-zero number (N) of bits;
• inserting, into a first portion of the coded data stream bits of coded data which do not belong to the first extracted sequence;
• performing a sequence test comprising at least 2N iterations of the following acts:
• obtaining a sequence of N bits, which is distinct from any sequences already tested;
• decoding and reconstructing a version of the current block from the bits of the sequence obtained and from coded data read in the first stream portion;
• evaluating, from the version of the reconstructed block, a likelihood measurement associated with the sequence obtained;
• determining a piece of information associated with the first sequence depending on likelihood measurements associated with the sequences tested;
• coding said information;
• inserting the coded information into a second portion of the encoded data stream;
• and
• performing at least one of transmitting the encoded data stream over a communication network or storing the encoded data stream on a non-transitory computer-readable medium.

A device comprising:

• a processor;
• a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the device to perform acts comprising:
• receiving an encoded data stream representative of at least one image from a communication network, said image being divided into blocks, said stream comprising a first portion and a second portion;
• decoding the encoded data stream, comprising:
• performing a sequence test comprising at least 2N iterations of the following acts for a current block, wherein N is a predetermined non-zero number:
• obtaining a sequence of N bits, which is distinct from any sequences already tested;
• decoding and reconstructing a version of the current block from the sequence obtained and from coded data read in the first stream portion;
• evaluating, from the version of the reconstructed block, a likelihood measurement associated with the sequence obtained;
• and
• the following acts, implemented for the current block:
• decoding a piece of information characteristic of a first sequence comprising the predetermined non-zero number of bits from the second stream portion;
• selecting a sequence identified among said at least two sequences tested, based on the measured likelihood measurement and the decoded information, said selected sequence being identified as the first sequence;
• and
• decoding and reconstructing the current block from the first sequence and the first stream portion.

A device comprising:

• a processor;
• a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the device to perform acts comprising:
• coding a coded data stream representative of at least one image, said image being divided into blocks, wherein coding comprises:
• the following acts implemented for a current block:
• encoding the current block into a plurality of encoded data;
• extracting the plurality of encoded data from a first sequence comprising a predetermined non-zero number (N) of bits;
• inserting, into a first stream portion, bits of coded data not belonging to the extracted sequence;
• performing a sequence test including at least 2N iterations of the following acts:
• obtaining a sequence of N bits, which is distinct from any sequences already tested;
• decoding and reconstructing a version of the current block from the bits of the sequence obtained and from coded data read in the first stream portion;
• evaluating, from the version of the reconstructed block, a likelihood measurement associated with the sequence obtained;
• determining a piece of information characteristic of the first sequence depending on likelihood measurements associated with the sequences tested;
• coding said information;
• inserting the coded information into a second stream portion of the encoded data stream;
• and
• performing at least one of transmitting the encoded data stream over a communication network or storing the encoded data stream on a non-transitory computer-readable medium.

At least one non-transitory computer-readable medium comprising a computer program stored thereon, comprising instructions for implementing a method of decoding an encoded data stream, when executed by a processor, wherein the encoded data stream is representative of at least one image, said image is divided into blocks, and said stream comprises a first portion and a second portion, and wherein decoding comprises:

• receiving the encoded data stream from a communication network;
• performing a sequence test comprising at least 2N iterations of the following acts for a current block, wherein N is a predetermined non-zero number:
• obtaining a sequence of N bits, which is distinct from any sequences already tested;
• decoding and reconstructing a version of the current block from the sequence obtained and from coded data read in the first stream portion;
• evaluating, from the version of the reconstructed block, a likelihood measurement associated with the sequence obtained;
• and
• the following acts, implemented for the current block:
• decoding a piece of information characteristic of a first sequence comprising the predetermined non-zero number of bits from the second stream portion;
• selecting a sequence identified among said at least two sequences tested, based on the measured likelihood measurement and the decoded information, said selected sequence being identified as the first sequence;
• and
• decoding and reconstructing the current block from the first sequence and the first stream portion.