A method for indicating size, shape and location of a region within a digital picture the picture being divided into a set of blocks. A value for at least one size parameter, which is indicative of a number of the blocks within said region is defined, and a value for at least one shape evolution parameter, which is indicative of a selection order of the blocks in said region is selected. Then preferably the values for said at least one size parameter and said at least one shape evolution parameter are encoded into a bitstream of a video sequence in order to indicate size, shape and location of the region within the picture.