1. A method of coding a video sequence in the form of a base level and a refinement level, wherein a group of pictures of the base level comprises intra coded or mono-predicted end images and bi-predicted images, and wherein the refinement level comprises at least one image with no temporal correspondent in the base level, the method comprising: predictive coding of said image with no temporal correspondent by making reference to a plurality of images, each image of said plurality of images being an image of the refinement level with no temporal correspondent in the base level or an image of the refinement level corresponding temporally to an end image; and determining as an anchoring image an image of the refinement level with no temporal correspondent in the base level and temporally neighboring an image of the base level that is bi-predicted with reference to the end images.