Inter-image prediction method and device and corresponding coding method and apparatus

1. A method for predicting a pixel block of an image using a weighted sum of pixel blocks belonging to patches of a dictionary (D l ) from a set of candidate patches (PS), each patch being formed of a pixel block of an image and a causal neighbourhood of this pixel block, the method comprising:

obtaining a subset of candidate patches (SPS) from the set of candidate patches (PS);

forming the dictionary (D l ) from a patch, denoted a first patch, belonging to the subset of candidate patches (SPS) and at least one other patch, denoted a second patch, belonging to said set of candidate patches (PS);

using a weighted linear combination of causal neighborhoods of said patches of said dictionary for predicting the causal neighborhood of the pixel block to be predicted;

using the weighting parameters of said linear combination chosen during the prediction of the causal neighborhood to predict the pixel block.

2. The method according to claim 1 , further comprising selecting the first patch for reducing a distance between said neighborhood of the first patch and the neighborhood of the patch that includes the block to be predicted.

3. The method according to claim 1 further comprising selecting each said second patch of the dictionary to reduce a distance between each said second patch and the first patch of said dictionary.

4. The method according to claim 1 further comprising selecting each candidate patch of said dictionary to reduce a distance between its neighborhood and the neighborhood of the patch comprising the bock to be predicted.

5. The method according to claim 1 , wherein the position in an image of a first patch of a dictionary is given by an item of displacement information defined from the patch formed of the block to be predicted and its causal neighborhood.

6. A method for encoding an image sequence during which a prediction block is calculated from an image pixel block, the prediction block being calculated according to a method of claim 1 .

7. A method for decoding an image sequence during which a prediction block is calculated from an image pixel block, the prediction block being calculated according to the method of claim 1 .

8. A device for decoding an image sequence during which a prediction block is calculated from an image pixel block, the prediction block being calculated according to the method of claim 7 .

9. A device for predicting a pixel block of an image configured to predict said block using a weighted sum of pixel blocks belonging to patches of a dictionary from a set of candidate patches, each patch being formed of a pixel block of an image and a causal neighborhood of this pixel block, the device comprising a processor configured to:

obtain a subset of candidate patches from the set of candidate patches;

form at least one dictionary from a patch of the subset of candidate patches and at least one other patch of said set of candidate patches, and

use a weighted linear combination of causal neighborhoods of said patches of said dictionary to predict the causal neighborhood of the pixel block to be predicted;

using the weighting parameters of said linear combination chosen during the prediction of the causal neighborhood to predict the pixel block.

10. The device according to claim 9 , further comprising a transmitter for transmitting a signal intended to be transmitted or received by said device, wherein the signal carries an item of information identifying the position of the first patch of the dictionary from which originates the prediction of the pixel block to be predicted.

11. The device according to claim 9 , further comprising selects the first patch for reducing a first distance between said neighborhood of the first patch and the neighborhood of the second patch that includes the block to be predicted.

12. The device according to claim 9 , further comprising selects each said second patch of the dictionary to reduce a second distance between each said second patch and the first patch of said dictionary.

13. The device according to claim 8 , further comprising selects each candidate patch of said dictionary to reduce a third distance between its neighborhood and the neighborhood of the patch comprising the block to be predicted.

14. The device according to claim 9 , wherein the position in an image of a first patch of a dictionary is given by an item of displacement information defined from the patch formed of the block to be predicted and its causal neighborhood.

15. The device according to claim 9 , further comprising a receiver for receiving a signal intended to be transmitted or received by said device, wherein the signal carries an item of information identifying the position of the first patch of the dictionary from which originates the prediction of the pixel block to be predicted.