Method and Apparatus for Encoding an Image Into a Video Bitstream and Decoding Corresponding Video Bitstream Using Enhanced Inter Layer Residual Prediction

A method for encoding an image of pixels according to a scalable encoding scheme having an enhancement layer and a reference layer, the method comprising for the encoding of a coding block in the enhancement layer in a coding mode called GRILP or DIFF inter:

• (a) determining a predictor of said coding block in the enhancement layer and the associated motion vector by a motion compensation step;
• (b) determining a first predictor block of the coding block;
• (c) determining a residual predictor block based on said motion compensation step and the reference layer;
• (d) determining a second predictor block by adding the first predictor block and said residual predictor block;
• (e) predictive encoding of the coding block using said second predictor block;
• and wherein the method further comprises:
• (f) forbidding the GRILP encoding mode and the DIFF inter encoding mode, or enabling the GRILP encoding mode or the DIFF inter encoding mode based on information pertaining to the reference picture, or enabling the GRILP encoding mode or the DIFF inter encoding mode based on the size of the coding block, or enabling the GRILP encoding mode or the DIFF inter encoding mode based on the size of the block in the reference layer collocated to the coding block, or disabling the GRILP encoding mode or the DIFF inter encoding mode for coding block when at least one of the collocated block in the reference layer is subject to bi-predictive encoding, for coding block subject to bi-predictive encoding.

A method for decoding a bit stream comprising data representing an image encoded according to a scalable encoding scheme having an enhancement layer and a reference layer, the method comprising for the decoding of said enhancement layer:

• (a) obtaining from the bit stream the motion vector associated to a prediction of a coding block within the enhancement layer to be decoded and a residual block;
• (b) determining a residual predictor block based on said location and the reference layer;
• (c) determining a first predictor block of the coding block;
• (d) determining a second predictor block by adding the first predictor block and said residual predictor block;
• (e) reconstructing the coding unit using the second predictor block and the obtained residual block;
• wherein at least one of the steps (b) to (e) involving an application of a single concatenated filter for cascading successive elementary filtering processes related to block processing including motion compensation and/or block upsampling and/or block filtering.

A method for encoding or decoding an image of pixels according to a scalable format having an enhancement layer and a reference layer, the method comprising for the encoding or the decoding of a coding block in the enhancement layer:

• (a) determining a first predictor of said coding block in the enhancement layer using an associated motion vector;
• (b) determining a second predictor block co-located to the first predictor block in the base layer;
• (c) determining a residual predictor block as the difference between the first and the second predictor block;
• (d) motion compensating the residual predictor block using the associated motion vector;
• (e) obtaining a third predictor block by adding the motion compensated residual block to the block of the base layer co-located to the coding block
• (f) predicting the coding block using said third predictor block;
• Wherein the first predictor is down-sampled to the resolution of the base layer before the determination of the residual predictor block.

A device for encoding an image of pixels according to a scalable encoding scheme having an enhancement layer and a reference layer, the device comprising for the encoding of a coding block in the enhancement layer in a coding mode called GRILP or DIFF inter:

• (a) means for determining a predictor of said coding block in the enhancement layer and the associated motion vector by a motion compensation step;
• (b) means for determining a first predictor block of the coding block;
• (c) means for determining a residual predictor block based on said motion compensation step and the reference layer;
• (d) means for determining a second predictor block by adding the first predictor block and said residual predictor block;
• (e) means for predictive encoding of the coding block using said second predictor block;
• and wherein the device further comprises:
• (f) means for forbidding the GRILP encoding mode and the DIFF inter encoding mode, or enabling the GRILP encoding mode or the DIFF inter encoding mode based on information pertaining to the reference picture, or enabling the GRILP encoding mode or the DIFF inter encoding mode based on the size of the coding block, or enabling the GRILP encoding mode or the DIFF inter encoding mode based on the size of the block in the reference layer collocated to the coding block, or disabling the GRILP encoding mode or the DIFF inter encoding mode for coding block when at least one of the collocated block in the reference layer is subject to bi-predictive encoding, for coding block subject to bi-predictive encoding.

A device for decoding a bit stream comprising data representing an image encoded according to a scalable encoding scheme having an enhancement layer and a reference layer, the device comprising for the decoding of said enhancement layer:

• (a) means for obtaining from the bit stream the motion vector associated to a prediction of a coding block within the enhancement layer to be decoded and a residual block;
• (b) means for determining a residual predictor block based on said location and the reference layer;
• (c) means for determining a first predictor block of the coding block;
• (d) means for determining a second predictor block by adding the first predictor block and said residual predictor block;
• (e) means for reconstructing the coding unit using the second predictor block and the obtained residual block;
• wherein at least one of the means (b) to (e) is configured for an application of a single concatenated filter for cascading successive elementary filtering processes related to block processing including motion compensation and/or block upsampling and/or block filtering.

A device for encoding or decoding an image of pixels according to a scalable format having an enhancement layer and a reference layer, the device comprising for the encoding or the decoding of a coding block in the enhancement layer:

• (a) a means for determining a first predictor of said coding block in the enhancement layer using an associated motion vector;
• (b) a means for determining a second predictor block co-located to the first predictor block in the base layer;
• (c) a means for determining a residual predictor block as the difference between the first and the second predictor block;
• (d) a means for motion compensating the residual predictor block using the associated motion vector;
• (e) a means for obtaining a third predictor block by adding the motion compensated residual block to the block of the base layer co-located to the coding block
• (e) a means for predicting the coding block using said third predictor block;
• Wherein the device comprises a means for down-sampling the first predictor to the resolution of the base layer before the determination of the residual predictor block.