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US 5,471,574 AGranted
Method for displaying a computer generated graphic on a raster output scanner
AssigneeXerox Corporation
InventorBindiganavele A. Prasad
Life of this patent
Estimating the term…
Abstract
A faster method of generating a mask stroke for a given trajectory. The first step is to determine if parallel lines can be developed for the entire trajectory. If not, the trajectory is divided into segments for each of which a set of parallel lines can be generated. The second step is to generate the parallel lines.
Claims2
A method for displaying a computer generated image described in page description language on a raster output scanner comprising the steps of:
- generating a trajectory from said page description language which trajectory is described in page description language
- approximating a part of said trajectory by an original parabola having control points A, B and C which original parabola approximates said part of said trajectory, to within a predetermined error limit,
- generating for said original parabola a set of approximating parabolas which approximating parabolas together constitute two curved lines that are parallel to, and a predetermined distance away from, said original parabola, said generating step comprising:
- a. determining a number of segments that the original parabola must be divided into in order that an approximating parabola can be generated for each segment,
- b. dividing said original parabola into said segments, and
- c. generating an approximating parabola for each of said segments, converting said set of approximating parabolas into a bit map, and sending said bit map to a raster output scanner,
- wherein said determining step comprises
- a. testing said original parabola having control points A, B, C by dividing distance AB by distance BC if distance AB is longer or distance BC by distance AB if distance BC is longer, to generate a result K and comparing the result K to a limit which is a function of included angle ABC,
- b. if the result is less than the limit, the parabola does not need to be subdivided,
- c. if the result is greater than the limit, the parabola is subdivided, and this method returns to step a. for each resultant segment.
7 more elements
A method for displaying a computer generated image described in page description language on a raster output scanner comprising the steps of:
- generating a trajectory from said page description language which trajectory is described in page description language
- approximating a part of said trajectory by an original parabola having control points A, B and C which original parabola approximates said part of said trajectory, to within a predetermined error limit,
- generating for said original parabola a set of approximating parabolas which approximating parabolas together constitute two curved lines that are parallel to, and a predetermined distance away from, said original parabola, said generating step comprising:
- a. determining a number of segments that the original parabola must be divided into in order that an approximating parabola can be generated for each segment,
- b. dividing said original parabola into said segments, and
- c. generating an approximating parabola for each of said segments, converting said set of approximating parabolas into a bit map, and sending said bit map to a raster output scanner,
- wherein said generating step for each approximating parabola A, B, C comprises
- determining lines A.sub.1 B.sub.1 and B.sub.1 C.sub.1 which are parallel to AB and BC, respectively, and
- using control points A.sub.1 B.sub.1 C.sub.1 to generate said approximating parabola.
6 more elements
Dependencies are inferred from the claim text.