Method and device for processing a sequence of digital images with spatial or quality scalability

摘要

A method of temporal prediction using motion estimation is implemented in a sequence of digital images, in the context of coding in a bitstream comprising at least first and second layers linked to each other in a chosen hierarchical relationship of scalability. Provision is made for constructing at least one set of reference pixels for the temporal prediction on the basis of information from a prediction image of the second layer and complementary information from an image of the first layer corresponding temporally to the prediction image. For each block of the current group of the image of the current second layer, a search is made for at least one block of the reference set of pixels so constructed that is suitable for the temporal prediction; and at least one corresponding motion vector is determined.

主权项

1. A method of temporal prediction using motion estimation in a sequence of digital images in the context of coding in a bitstream comprising at least first and second layers linked to each other in a chosen hierarchical relationship of scalability, each image of the second layer comprising a plurality of groups of blocks of pixels, said coding enabling access to spatial parts of the images, the method of temporal prediction being applied to at least one current group of an image of a current second layer of the sequence, wherein the method comprises the following steps:
constructing at least one set of reference pixels for the temporal prediction on the basis of information from a prediction image of the second layer from a prediction image of the second layer, or, if signaled, spatially complementary information from an image of the first layer corresponding temporally to said prediction image, wherein pixels in an image of the second layer that are used for temporal prediction are restricted to a group of blocks of said prediction image corresponding to a group of pixels to be predicted; and for each block of the current group of the image of the current second layer, searching for at least one block of the referenced set of pixels so constructed that is suitable for the temporal prediction, and determining at least one corresponding motion vector; and wherein the bitstream further comprises a third layer and the step of constructing at least one reference set of pixels comprises a step of increasing the number of reference pixels for the temporal prediction on the basis of complementary information from an image of the third layer temporally corresponding to said prediction image.