1. A method of searching for a query object in an image or sequence of images by processing signals corresponding to the images using a processor, the method comprising: providing a plurality of stored images or sequences of images, each image or sequence of images containing a two-dimensional projection of a three-dimensional object in a perspective view; for each image or sequence of images, providing an object descriptor, each object descriptor including a plurality of perspective view descriptors, each perspective view descriptor representing the outline of the shape of a two-dimensional projection of said three-dimensional object from a different perspective view of said three-dimensional object, including a perspective view not in the image or sequence of images; inputting a query in the form of a query outline which is the outline of the shape of a two-dimensional projection of a three-dimensional query object in a perspective view; deriving a query object descriptor of the query object using the query outline; comparing said query object descriptor with at least one of said object descriptors; selecting and displaying at least one result, which is an image or sequence of images containing an object for which comparison between the object descriptor and the query object descriptor indicates a degree of similarity between the query object and said object, wherein said object matches the query object but the selected and displayed image or sequence of images does not include said object in the same perspective view as the perspective view of the query object in said query.