Method and device for decoding a scalable stream representative of an image sequence and corresponding coding method and device

A method for coding a sequence of images in the form of a scalable stream comprising a base layer and at least one enhancement layer, the method comprising:

• coding at least one image in said base layer and reconstructing said at least one image,
• coding enhancement data in a first part of said at least one enhancement layer relating to a group of a plurality of blocks, said enhancement data comprising at least one item of information for identifying at least one region of said reconstructed at least one image,
• processing said at least one region of said reconstructed at least one image identified by said at least one item of information,
• obtaining residues for at least a first block and a second block of said group from said at least a first block and a second block and from said processed at least one region, wherein the residues for the first block are obtained from another image previously reconstructed and the residues for the second block are obtained from another image of the enhancement layer, and
• coding the residues for at least a first block and a second block in a second part of said at least one enhancement layer.

A decoder configured for decoding a scalable stream comprising a base layer and at least one enhancement layer, the decoder comprising an input interface configured to access said scalable stream and at least one processor configured to:

• reconstruct at least one image from said base layer,
• decode a first part of said at least one enhancement layer relating to a group of a plurality of blocks into decoded enhancement data which comprise at least one item of information for identifying at least one region of said reconstructed at least one image,
• process said at least one region of said reconstructed at least one image identified by said at least one item of information,
• obtain residues for at least a first block and a second block of said group from a second part of said at least one enhancement layer, wherein the residues for the first block are obtained from another image previously reconstructed and the residues for the second block are obtained from another image of the enhancement layer, and
• reconstruct the at least a first block and a second block from said residues and from said processed at least one region.

A coder configured to code a sequence of images in the form of a scalable stream comprising a base layer and at least one enhancement layer, the coder comprising an input interface configured to access said sequence of images and at least one processor configured to:

• code at least one image of said accessed sequence in said base layer and reconstruct said at least one image,
• code enhancement data in a first part of said at least one enhancement layer relating to a group of a plurality of blocks, said enhancement data comprising at least one item of information for identifying at least one region of said reconstructed at least one image,
• process said at least one region of said reconstructed at least one image identified by said at least one item of information,
• obtain residues for at least a first block and a second block of said group from said at least a first block and a second block and from said processed at least one region, wherein the residues for the first block are obtained from another image previously reconstructed and the residues for the second block are obtained from another image of the enhancement layer, and
• code the residues for at least a first block and a second block in a second part of said at least one enhancement layer.

A computer program product stored in a non-transitory computer readable storage medium for decoding a scalable stream having a base layer and at least one enhancement layer, comprising computer-executable instructions for:

• reconstructing at least one image from said base layer,
• decoding a first part of said at least one enhancement layer relating to a group of a plurality of blocks into decoded enhancement data which comprise at least one item of information for identifying at least one region of said reconstructed at least one image,
• processing said at least one region of said reconstructed at least one image identified by said at least one item of information,
• obtaining residues for at least a first block and a second block of said group from a second part of said at least one enhancement layer, wherein the residues for the first block are obtained from another image previously reconstructed and the residues for the second block are obtained from another image of the enhancement layer, and
• reconstructing the at least a first block and a second block from said residues and from said processed at least one region.