1. A method for segmenting a frame of pixels into a plurality of blocks each having a block type, comprising the steps of: a) performing an initial segmentation of the frame into a set of initial blocks, thus determining, for each initial block, a block type associated with the concerned initial block; b) determining, for each block type, an associated set of quantizers based on data corresponding to pixels of blocks having said block type; c) selecting, among a plurality of possible segmentations defining an association between each block of this segmentation and an associated block type, the segmentation which minimizes an encoding cost estimated based on a measure of the rate necessary for encoding each block using the set of quantizers associated with the block type of the encoded block according to the concerned segmentation.