1. A method of representing an object appearing in an image or a sequence of images, using at least one processor to process signals corresponding to a two-dimensional outline of the object, the method comprising: deriving, using said at least one processor, a plurality of numerical values representing features appearing on the outline of the object based on the signals; and applying a transformation to the derived values to generate a representation of the outline, wherein the transformation is in the form of y′=a pow(y,b)+c, and further wherein a, b and c are constants, y is a value being transformed, y′ is a result of the transformation, and pow(y,b) denotes y to the power b, and further wherein b is greater than zero and less than 1.