Method and apparatus for representing and searching for an object using shape
A method is disclosed for representing a sequence of images constituting a moving image by processing signals corresponding to the image. An object appearing in one image is identified in the sequence in a first perspective view, and the same object appearing in another image is identified in the sequence in a second perspective view. A view descriptor of the outline of the object in the first perspective view is derived and at least one additional view descriptor of the outline of the object in another perspective view is also derived. The two or more view descriptors are associated to form a descriptor which is a single indexable entity for the sequence of images.
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.
2. A method as claimed in claim 1 wherein the image is part of a sequence of images, and at least one additional view descriptor corresponds to a view of the object appearing elsewhere in the image sequence.
3. A method as claimed in claim 1 wherein the image is from a video.
4. A method as claimed in claim 1 wherein the view descriptors are derived using a curvature scale space representation.
5. A method as claimed in claim 1 further comprising deriving a descriptor of the object which is related to the shape or size of the object and which is independent of the view of the object in the image.
6. A method as claimed in claim 5 wherein said view-independent descriptor corresponds to the volume of the object.
7. A computer-implemented method of representing an object appearing in an image to index the respective image or sequence of images of which it is a part for searching purposes, the method comprising:
extracting, using a processor, a two-dimensional outline of an object appearing in the image in a first perspective view;
identifying the object;
identifying, using a processor, 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 and obtaining, from an extracted image, at least one additional outline of the object in a perspective view different from said first perspective view;
deriving, using a processor, a plurality of view descriptors corresponding to a plurality of two-dimensional outlines of the object in different views, by processing signals corresponding to the outlines; and
associating the view descriptors to form an object descriptor to index the respective image or image sequence.
8. An apparatus comprising:
a descriptor database storing descriptors of an object or parts of an object appearing in images; and
a processor configured to perform the method of claim 1 or claim 7 .
9. A non-transitory computer-readable storage medium storing computer-executable process steps for implementing a method as claimed in claim 1 or claim 7 .
10. A computer system comprising:
a descriptor database storing descriptors of objects or parts of objects appearing in images; and
a control unit configured to perform the method of claim 1 or claim 7 .