Printer driver software product with edge runlength encoder
View Patent ↗A printer driver software product includes machine readable instructions for a computer to compress bi-level page description date. The computer, in accordance with the instructions, checks to determine if an edge of a black region in a line of the page is within a predetermined range of pixels from an edge of a black region in a previous line of pixels. If the edge falls within the predetermined range then a symbol is written indicating the presence of the edge and the offset from the referenced edge in the previous line. The end of each line of pixels is determined on the basis of a parameter indicating page width.
1. A printer driver software product stored on a computer readable medium for providing instructions containing a machine readable program for a processor to compress a page layout having lines of black and white pixels representing black regions on a white background, said software product including:
instructions to determine if an edge of a black region in a first lie is within a predetermined range of pixels from an edge of a line of black pixels in a previous line; and
instructions to determine the end of each of said lines on the basis of data indicating width of the page layout.
2. A printer driver software product according to claim 1 , wherein the predetermined range of pixels is plus-or-minus two pixels.
3. A printer driver software product according to claim 1 , including instructions to encode the edge of the black region in the first line relative to the edge of the line of black pixels in the previous line as a first one of a set of predetermined symbols plus-or-minus an integer within the predetermined distance.
4. A printer driver software product according to claim 3 , including instructions to encode an edge of a line of the black regions as a run length from a previous edge of the line.
5. A printer driver software product according to claim 3 , including instructions to encode an edge kill operation as a second one of the set of predetermined symbols.
6. A printer driver software product according to claim 3 , including instructions to encode an edge created operation as another of the set of predetermined symbols.
7. A printer driver software product according to claim 3 , wherein the set of predetermined symbols is entropy coded.