Vector coding of computer graphics material
AssigneeBell Telephone Laboratories, Incorporated
InventorsWilliam Pferd, Krishan Ramachandran
Life of this patent
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Abstract
Computer graphics material after raster scanning and digitizing is examined for linear narrow width areas of like light value, typically black or white. Runs of like value on successive scan lines are compared for contiguity and, when found, are compactly coded by coordinates of first and last scan lines defining each area and thickness. Data compaction ratios up to 36 to 1, as compared to the amount of data required to store data for every picture element, can be achieved in real time.
Claims9
Apparatus for encoding line vectors from raster digital data defining light intensities of two-dimensional line drawings, said raster including a plurality of scan lines each containing a fixed number of picture elements comprising first and second register means for storing transition data between picture elements of unlike light intensity from consecutive pairs of scan lines, means for comparing the contents of said first and second registers to determine from the matching occurrence of like transitions along such consecutive scan lines whether or not line vectors are present, and means for generating and storing in additional registers numerical coordinates of start and finish picture elements of connectible vectors by scan line order and picture element position along a scan line from a raster edge together with a thickness factor.
Apparatus for encoding linear vectors from raster data defining the picture elements of two-dimensional line drawings in which a raster includes a plurality of lines parallel to one border thereof with a predetermined number of picture elements each, first and second shift registers connectable in the alternative in series relationship in an input mode and individually reentrant in a processing mode, a scanning controller, a vector processor and an image memory further comprising
- means for entering scan line data from pairs of successive scan lines consecutively into said first and second shift registers in said input mode,
- means for matching transitions between binary data states defining vector edges on consecutive pairs of adjacent scan lines in said processing mode in accordance with counts of distances from a second border normal to said one border within tolerances of a predetermined number of picture elements from said one border to the opposite parallel border over a complete raster scan as scan line data are circulated back and forth through said first means by means of said controller,
- first means for inserting into said image memory the coordinates encoded as counts along each scan line from said second border as a reference and the order of the scan line of the start of each connectible vector together with the number of picture elements between transitions of opposite type therealong, and
- second means for entering into said image memory the coordinates of the finish of each vector measured from said second border and the order of the scan line, each vector being matched from scan line to scan line to determine that matching edges are within a predetermined tolerance.
Dependencies are inferred from the claim text.