Communications: electrical – Digital comparator systems
Patent
1975-01-27
1976-10-19
Boudreau, Leo H.
Communications: electrical
Digital comparator systems
3401463MA, G06K 916
Patent
active
039874125
ABSTRACT:
A binary image containing objects comprised of black picture elements (pels) in a bit-addressable random access memory, is scanned in a predetermined order, until a black pel is encountered. The object is then encircled by a boundary follower in a clockwise direction, and each pel is recorded as it is encountered in a chain link format. Each black pel is changed to white as it is encountered provided it is not an interior boundary point. 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 except for the interior boundary. At this point, the remaining interior boundary pels are traced out and encoded in the same chain link format.
Objects within objects are also encoded. A stack is provided to store the coordinates of the occurrence of each mode change described below. As the follower traces out the outer boundary and begins to strip out the object interior, the first time an inner boundary point is observed, the follower puts its location in the stack, steps over to the inner boundary and follows all the way around the inside in a counterclockwise direction encoding the pels encountered. An outer vs. inner test is done to assure that the supposed inner boundary is not really a thin point in the shrinking object. After the inner boundary is encoded, the follower begins to blacken its interior. If a black point is encountered, it is theorized to be the outer boundary of an object which is inside the inner boundary just encoded. This is verified by means of the outer vs. inner test. The follower puts its location in the stack and encodes the object found in the same manner as above. This generates encoded data which has a nested structure.
Decompression is accomplishd in two steps. The outer boundary is traced out and the entire interior is made black, and then each inner boundary is traced out and their interiors are made white.
REFERENCES:
patent: 3303465 (1967-02-01), Essinger et al.
patent: 3593283 (1971-07-01), Miyamoto et al.
patent: 3605093 (1971-09-01), Parks et al.
patent: 3609685 (1971-09-01), Deutsch
patent: 3863218 (1975-01-01), Oka et al.
Sidhu et al., "Property Encoding:Application in Binary Picture Encoding and Boundary Following," IEEE Transactions on Computers, vol. C-21, No. 11, 11-1972, pp. 1206-1215.
Kruse, "A Parallel Picture Processing Machine," IEEE Transactions on Computers, vol. C-22, No. 12, Dec. 1973, pp. 1075-1087.
Boudreau Leo H.
Brodie R. Bruce
International Business Machines - Corporation
Schmid, Jr. Otto
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