1. A method of representing an object appearing in an image, wherein the object appears in the image with a first two-dimensional outline in a first perspective view, by processing signals corresponding to the image using one or more processors, the method comprising: extracting, using a processor, the first two-dimensional outline of the object in the image; deriving, using a processor, a view descriptor of the first two-dimensional outline of the object in the first perspective view; identifying the object; identifying at least one image in a database of images that includes the object, or a different example of the object, in a perspective view different from the first perspective view; extracting, using a processor, at least one of the identified images from the database; obtaining, using a processor, from the extracted image at least one additional outline of the object in a perspective view different from said first perspective view; deriving, using a processor, at least one additional view descriptor of an outline of the object in a perspective view different from said first perspective view; and associating, using a processor, the two or more view descriptors representing the outlines of the object from different perspective views to form an object descriptor.