METHOD OF CODING AND DECODING IMAGES, DEVICE FOR CODING AND DECODING IMAGES AND COMPUTER PROGRAMMES CORRESPONDING THERETO

• US 20200137419A1
• Filed: 12/27/2019
• Published: 04/30/2020
• Est. Priority Date: 08/31/2015
• Status: Active Grant

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Philippe, Pierrick, Arrufat, Adria
• Granted Patent: US 10,911,784 B2
• Time in Patent Office: Days
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/12 Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
• CPC Class Codes: H04N 19/157 Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A method of coding at least one image sliced into blocks. The method implements, for a current block to be coded: predicting the current block in accordance with a prediction mode selected from among predetermined prediction modes, Intra and Inter, the selected mode of prediction being Intra; calculating a residual data block representative of a difference between a predictor block obtained on completion of the prediction and the current block; applying a transform operation to the data of the residual block, the transform operation belonging to a set of transform operations previously stored in association with the selected mode of Intra prediction; and coding the data obtained from the transform operation. The number of transform operations contained in the set associated with the selected Intra mode is different from the number of transform operations contained in a set of transform operations stored in association with the mode of Inter prediction.

Claims

1. A method comprising

coding at least one image split up into blocks, implementing by processing circuitry of a coding device, for a current block to be coded of said image:

predicting the current block in accordance with a mode of prediction selected by the coding device from among two predetermined modes of prediction Intra and Inter, the selected mode of prediction being Intra,

calculating a residual data block representative of a difference between a predictor block obtained on completion of the predicting and the current block,

applying a transform operation to data of said residual data block, said transform operation belonging to a set of transform operations which is stored in a non-transitory computer-readable medium in passociation with the selected mode of Intra prediction,

coding data obtained subsequent to said transform operation,

constructing a data signal containing said coding data and an index of said applied transform operation,

transmitting said data signal to a decoding device,

prior to coding the image, storing in the non-transitory computer-readable medium said set of transform operations in association with the selected mode of Intra prediction and a set of transform operations in association with the mode of Inter prediction, wherein the number of transform operations contained in the set of transform operations that is associated with said selected mode of Intra prediction is different from the number of transform operations contained in the set of transform operations that is stored in association with said mode of Inter prediction.

2. The coding method as claimed in claim 1, in which:

the set of transform operations that is associated with the mode of Intra prediction contains at least one separable transform operation and at least one non separable transform operation,

the set of transform operations that is associated with the mode of Inter prediction contains only at least one separable transform operation.

3. The coding method as claimed in claim 1, in which for said two sets of transform operations, the number of transform operations in each of said two sets contains in common at least one identical transform operation.

4. The coding method as claimed in claim 1, in which the set of transform operations which is associated with said selected mode of Intra prediction is stored in association with at least one other mode of prediction different from said two of predetermined modes of prediction.

5. A device for coding at least one image split up into blocks, comprising:

a non-transitory computer-readable medium comprising a set of transform operations stored thereon in association with each of two predetermined modes of prediction Intra and Inter;

a processing circuit which is configured to, for a current block to be coded of said image;

predict the current block in accordance with a mode of prediction selected from among the plurality of predetermined modes of prediction, the selected mode of prediction being Intra,

calculate a residual data block representative of a difference between a predictor block obtained on completion of the prediction and the current block,

apply a transform operation to data of said residual data block, said transform operation belonging to the set of transform operations that is stored in association with the selected mode of Intra prediction,

code data obtained subsequent to said transform operation,

construct a data signal containing said coding data and an index of said applied transform operation,

transmit said data signal to a decoding device,

wherein the number of transform operations contained in the set of transform operations that is associated with said selected mode of Intra prediction is different from the number of transform operations contained in the set of transform operations that is stored in association with said mode of Inter prediction.

6. A method comprising:

decoding a data signal representative of at least one image split up into blocks, implementing by processing circuitry of a decoding device, for a current block to be decoded;

determining, in said data signal;

data representative of a current residual block associated with the current block to be decoded,

a mode of prediction of the current block to be decoded, said mode of prediction belonging to two predetermined modes of prediction Intra and Inter, the determined mode of prediction being Intra,

an index of a transform operation,

predicting the current block in accordance with the determined mode of Intra prediction,

applying the transform operation corresponding to the determined index to the data representative of said residual block, said transform operation belonging to a set of transform operations which is stored in a non-transitory computer-readable medium in association with said determined mode of Intra prediction,

reconstructing the current block with the aid of a predictor block obtained on completion of the prediction and of data obtained subsequent to said transform operation; and

prior to decoding the data signal, storing in the non-transitory computer-readable medium the set of transform operations associated with the determined mode of Intra prediction and the set of transform operations associated with the mode of Inter prediction, wherein the number of transform operations contained in said set of transform operations associated with the determined mode of Intra prediction is different from the number of transform operations contained in the set of transform operations which is stored in association with said mode of Inter prediction.

7. The decoding method as claimed in claim 6, in which:

the set of transform operations that is associated with the mode of Intra prediction contains at least one separable transform operation and at least one non separable transform operation,

the set of transform operations that is associated with the mode of Inter prediction contains only at least one separable transform operation.

8. The decoding method as claimed in claim 6, in which for said two sets of transform operations, the number of transform operations in each of said two sets contains in common at least one identical transform operation.

9. The decoding method as claimed in claim 6, in which the set of transform operations which is associated with said determined mode of Intra prediction is stored in association with at least one other mode of prediction different from said mode of Inter prediction.

10. A device for decoding a data signal representative of at least one image split up into blocks, comprising:

a non-transitory computer-readable medium comprising a set of transform operations stored thereon in association with each of two predetermined modes of prediction Intra and Inter;

a processing circuit which is configured to, for a current block to be decoded;

determine, in said data signal;

data representative of a current residual block associated with the current block to be decoded,

a mode of prediction of the current block to be decoded, said mode of prediction being Intra,

an index of a transform operation,

predict the current block in accordance with the mode of Intra prediction,

apply the transform operation corresponding to the determined index to the data representative of said residual block, said transform operation belonging to the set of transform operations that is stored in association with said mode of Intra prediction,

reconstruct the current block with the aid of a predictor block obtained on completion of the prediction and of the data obtained subsequent to said transform operation,

wherein the number of transform operations contained in said set of transform operations that is associated with the determined mode of Intra prediction is different from the number of transform operations contained in the set of transform operations that is stored in association with the mode of Inter prediction.

11. The device for decoding as claimed in claim 10, in which:

the set of transform operations that is associated with the mode of Intra prediction contains at least one separable transform operation and at least one non separable transform operation,

the set of transform operations that is associated with the mode of Inter prediction contains only at least one separable transform operation.

12. A non-transitory computer-readable medium comprising a computer program stored thereon comprising program code instructions for execution of a method of decoding a data signal representative of at least one image split up into blocks, when said program is executed on a computer of a decoding device, wherein the method comprises:

implementing by the decoding device, for a current block to be decoded;

determining, in said data signal;

data representative of a current residual block associated with the current block to be decoded,

a mode of prediction of the current block to be decoded, said mode of prediction being Intra,

an index of a transform operation,predicting the current block in accordance with the mode of Intra prediction,

applying the transform operation corresponding to the determined index to the data representative of said residual block, said transform operation belonging to a set of transform operations which is stored in a non-transitory computer-readable medium in association with said mode of Intra prediction,

reconstructing the current block with the aid of a predictor block obtained on completion of the prediction and of data obtained subsequent to said transform operation; and

prior to decoding the data signal, storing in the non-transitory computer-readable medium the set of transform operations associated with the determined mode of Intra prediction and the set of transform operations associated with the mode of Inter prediction, wherein the number of transform operations contained in said set of transform operations associated with the determined mode of Intra prediction is different from the number of transform operations contained in the set of transform operations which is stored in association with said mode of Inter prediction.