1. Device for compressing a source image by means of a base layer, coding a base image, and of an enhancement layer, coding a residual existing between the source image and the base image, the source image and the base image being structured as blocks of pixels, comprising means for generating the enhancement layer of a block (k) as a function of the quality (psnr k ) of restitution of this block (k), determined by comparing the coding of this block in the source image with the coding of this block in the base image, and/or as a function of information coded by this block of pixels.