Method and apparatus for outline font character generation in dot matrix devices
First Claim
1. Apparatus for converting an outline font represented by a control point stream into bit mapped data suitable for driving dot matrix display devices, comprising:
- point transform means responsive to said control point stream and operative to generate a transformed point stream;
flattening means responsive to said transformed point stream and operative to generate a set of normalized polysegments defined by end point data wherein the length of each polysegment has a predetermined relationship to the dimensions of a pixel to be printed or displayed;
transition detection means responsive to said normalized polysegments and operative to develop a set of flag signals and initial transition pixel data locating a transition pixel relative to each polysegment intersected by a reference line passing through a particular point of each pixel in a row of pixels, a transition pixel being defined as a pixel at which a data state transition occurs;
intermediate storage means for storing transition pixel data;
transition processing means responsive to the transition pixel data developed by said transition detection means, a plurality of process parameters, and said set of flag signals, and operative to compare said initial transition pixel data to transition pixel data previously stored in said intermediate storage means and to generate intermediate transition pixel data for return to said intermediate storage means;
bitmap converter means responsive to said stored intermediate transition pixel data, and operative to generate bitmap data; and
output means responsive to said bitmap data and operative to generate output character data corresponding thereto.
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Abstract
Method and apparatus for outline font character generation in dot matrix devices including a point transform engine, a parametric equation generator, an adaptive forward differencing engine, a transition detection engine, a transition processor, an intermediate storage, and a bitmap converter. The point transform engine performs a linear transformation on the input control points to produce a set of control points corresponding to the description of the scaled image. The parametric equation generator computes a set of coefficients used in generating polysegments. The adaptive forward differencing engine generates a set of controlled length vectors representing the image, while the transition detection engine determines the transition pixels by scanning the vectors both horizontally and vertically to determine whether a scanline is crossed by the vector. The transition processor enhances the image quality and alters the number and location of the previously determined transition pixel. The transition locations for the image are accumulated in the intermediate storage until all curves of the image have been processed. The bitmap converter converts, on a line-by-line basis, the transition information into bitmap format.
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Citations
17 Claims
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1. Apparatus for converting an outline font represented by a control point stream into bit mapped data suitable for driving dot matrix display devices, comprising:
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point transform means responsive to said control point stream and operative to generate a transformed point stream; flattening means responsive to said transformed point stream and operative to generate a set of normalized polysegments defined by end point data wherein the length of each polysegment has a predetermined relationship to the dimensions of a pixel to be printed or displayed; transition detection means responsive to said normalized polysegments and operative to develop a set of flag signals and initial transition pixel data locating a transition pixel relative to each polysegment intersected by a reference line passing through a particular point of each pixel in a row of pixels, a transition pixel being defined as a pixel at which a data state transition occurs; intermediate storage means for storing transition pixel data; transition processing means responsive to the transition pixel data developed by said transition detection means, a plurality of process parameters, and said set of flag signals, and operative to compare said initial transition pixel data to transition pixel data previously stored in said intermediate storage means and to generate intermediate transition pixel data for return to said intermediate storage means; bitmap converter means responsive to said stored intermediate transition pixel data, and operative to generate bitmap data; and output means responsive to said bitmap data and operative to generate output character data corresponding thereto. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of converting an outline font represented by a control point stream into bit mapped data suitable for driving dot matrix display devices, comprising the steps of:
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converting said control point stream into a transformed point stream; using said transformed point stream to generate a set of normalized polysegments wherein the length of each polysegment has a predetermined relationship to the dimensions of a pixel to be printed or displayed; using said normalized polysegments to develop initial transition pixel data including transition address information and flag signals locating a transition pixel relative to each polysegment intersected by a reference line passing through a particular point of each pixel in a row of pixels, a transition pixel being defined as a pixel at which a data state transition occurs; using a plurality of process parameters to compare said initial transition pixel data to previously stored corresponding transition pixel data to generate intermediate transition pixel data; storing said intermediate transition pixel data; using said stored intermediate transition pixel data to generate bitmap data; and using said bitmap data to generate output character data corresponding thereto. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification