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Contour Coding of Black White Images Without Recursion

IP.com Disclosure Number: IPCOM000086356D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Morrin, TH: AUTHOR

Abstract

A black-white image compression technique which is based on the chain-link encoding of the boundaries of objects is described in a paper by T. H. Morrin, entitled "Recursive Contour Coding of Nested Objects in Black/White Images", published in ICC '75, San Francisco, June, 1975.

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Contour Coding of Black White Images Without Recursion

A black-white image compression technique which is based on the chain-link encoding of the boundaries of objects is described in a paper by T. H. Morrin, entitled "Recursive Contour Coding of Nested Objects in Black/White Images", published in ICC '75, San Francisco, June, 1975.

A binary image containing objects comprised of black picture elements (pels) in a bit-addressable random-access memory, is raster scanned until a black pel is encountered. The object is then encircled by a boundary follower and each pel is encoded as it is encountered in a chain-link format. After the object has been completely encircled by the follower, encoding of the points is temporarily terminated. The follower continues to encircle the object several times, deleting black pels as it goes, until all of the black points in the object are exhausted or an interior boundary is encountered, which is adjacent to the border of a hole.

If a potential hole border point is observed by the follower to be 4-adjacent to its current location X, the presence of a hole is tested for by following the border of the potential hole until the initial point is returned to. If the border tested is indeed a hole border, and not part of the set of white pels that surrounds the object, it is encoded by following the hole border around again and chain encoding the path in the same manner as the object was encoded.

When this is completed, location X on the border of the pa...