1. A method of representing an object appearing in an image or a sequence of images, by processing signals corresponding to the image, the method comprising deriving a plurality of numerical values representing features appearing on the outline of the object on the basis of the signals and applying a transformation to said values to arrive at a representation of the outline, wherein said transformation is in the form of z′=a pow (z,b)+c, where a, b and c are constants and pow (z,b) denotes z to the power b, and wherein b is greater than zero and less than 1.