The invention relates to a method of coding segmented pictures, or partitions, divided into homogeneous regions. Said method, called intra-mode coding process, comprises, for each successive partition, the steps of translating the picture of the labels associated to the regions into a description in terms of a contour element chain in which the elements are defined by means of their movements through successive basic cells, tracking inside each successive cell each contour from its initial contour point, previously extracted, to its end by storing chain symbols corresponding both to input, internal and output contour elements of said cell and to priorities between possible multiple outputs elements, and repeating these steps up to the end of each successive contour segment of the concerned partition. The information corresponding in each cell to the initial point of each contour segment and to the associated chain of movements between that initial point and the initial one of the following cell is finally coded.