1. A method for representing an object appearing in an image, using at least one processor to process signals corresponding to the image, comprising: identifying at least one object outline; determining, using said at least one processor, a curvature scale space representation for said outline to generate peak coordinates for the outline curvature scale representation, wherein said peak coordinates are determined using a plural stage filter that produces derivative curves representative of said outline by convolving said object outline, the plural stage filter having a parameter corresponding to an arc-length parameter whereby the coordinates of the characteristic curves, and said peak coordinates, correspond to an arc-length parameter of the outline and a smoothing parameter; and ordering said peak coordinates, by selecting highest peak value and associated highest peak coordinates and ordering remaining peak coordinates in decreasing peak height, to generate a shape descriptor for said outline.