Method of predicting motion and texture data

1. Method for generating for at least one block of pixels of a picture of a sequence of high resolution progressive pictures, called high resolution sequence, at least one motion predictor from motion data associated with the pictures of a sequence of low resolution interlaced pictures, called low resolution sequence, each interlaced picture comprising a top field interlaced with a bottom field and that can be coded in frame mode or in field mode, a temporal reference being associated with each progressive picture and each field of interlaced picture, wherein said method comprises:

generating said at least one motion predictor for the said at least one block of pixels of the said high resolution picture on the basis of motion data associated with at least one block of pixels of the top and/or bottom field of a low resolution picture of the same temporal reference as the said high resolution picture when the said low resolution picture is coded in field mode; and generating said at least one motion predictor for the said at least one block of pixels of the said high resolution picture on the basis of motion data associated with at least one block of pixels of the said low resolution picture, when the said high resolution picture is of the same temporal reference as the top or bottom field of the low resolution picture and the said low resolution picture is coded in frame mode.

2. Method according to claim 1 , wherein, when the said low resolution picture is coded in field mode, the said at least one motion predictor is generated by sub-sampling the said motion data associated with the said at least one block of pixels of the said top and/or bottom field of the said low resolution picture of the same temporal reference as the said high resolution picture with a horizontal inter-layer ratio in the horizontal direction of the picture and a first vertical inter-layer ratio in the vertical direction of the picture.

3. Method according to claim 2 , wherein when the said low resolution picture is coded in frame mode and when the said high resolution picture is of the same temporal reference as the top or bottom field of the said low resolution picture, the said at least one motion predictor is generated by subsampling the said motion data associated with the said at least one block of pixels of the said low resolution picture with the said horizontal inter-layer ratio in the horizontal direction of the picture and a second vertical inter-layer ratio in the vertical direction of the picture.

4. Method according to claim 2 , wherein a texture predictor is generated for the said at least one block of pixels of the said high resolution picture on the basis of the texture data associated with the at least one block of pixels of the top or bottom field of the low resolution picture of the same temporal reference as the said high resolution picture.

5. Method according to claim 4 , wherein the said texture predictor is generated by subsampling the said texture data associated with the said at least one block of pixels of the top or bottom field of the said low resolution picture of the same temporal reference as the said high resolution picture with the said horizontal inter-layer ratio in the horizontal direction of the picture and the said first vertical inter-layer ratio in the vertical direction of the picture.

6. Method according to claim 3 , wherein said horizontal inter-layer ratio is equal to the width of the high resolution pictures divided by the width of the fields of the low resolution pictures, said first vertical inter-layer ratio is equal to the height of the high resolution pictures divided by the height of the fields of the low resolution pictures and in that the second vertical inter-layer ratio is equal to the height of the high resolution pictures divided by the height of the low resolution pictures.

7. Method according to claim 1 , wherein the motion data associated with the low resolution pictures comprises motion vectors.

8. Method according to claim 7 , wherein the motion vectors associated with the low resolution picture that are coded in frame mode or with each of the top and bottom fields of the low resolution picture coded in field mode have the same parity.

9. Method according to claim 1 , wherein said method is used by a method of encoding high resolution pictures from low resolution pictures.

10. Method according to claim 9 , wherein the low resolution pictures are encoded according to the MPEG-4 AVC standard.

11. Method according to claim 1 , wherein said method is used by a method of decoding high resolution pictures from low resolution pictures.