Line smoothing for a raster display
First Claim
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1. A display system for smoothing out stair-step effects in the raster display of information having line segments, said display system comprising:
- a raster scanned display including a surface having a plurality of pixels for displaying information to a viewer; and
a display generator for generating video signals to control said display in displaying line segments, said display generator including;
(a) a brightness generator responsive to input signals for dividing each line segment to be displayed into a plurality of sections each made up of one or more pixels and for determining individual brightness values of said pixels in proportion to the amount of surface area of those of said pixels in each section overlaid by said line segment to be displayed,(b) a memory,(c) means responsive to pixel address signals for addressing said memory to store said pixel brightness values in memory locations associated with each said pixel of each section, and(d) a video sequence generator for addressing said memory in a predetermined sequence to retrieve said pixel brightness values pursuant to the generation of said video signals to said raster display.
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Abstract
This invention relates to a method of and apparatus for displaying a symbol on a display surface consisting of a matrix of discrete points (e.g. raster), where the symbol is divided into sections and the brightness of each pixel is controlled. This technique smooths out "stair-step" effects inherent in displays consisting of discrete points.
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Citations
12 Claims
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1. A display system for smoothing out stair-step effects in the raster display of information having line segments, said display system comprising:
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a raster scanned display including a surface having a plurality of pixels for displaying information to a viewer; and a display generator for generating video signals to control said display in displaying line segments, said display generator including; (a) a brightness generator responsive to input signals for dividing each line segment to be displayed into a plurality of sections each made up of one or more pixels and for determining individual brightness values of said pixels in proportion to the amount of surface area of those of said pixels in each section overlaid by said line segment to be displayed, (b) a memory, (c) means responsive to pixel address signals for addressing said memory to store said pixel brightness values in memory locations associated with each said pixel of each section, and (d) a video sequence generator for addressing said memory in a predetermined sequence to retrieve said pixel brightness values pursuant to the generation of said video signals to said raster display. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for overcoming stair-step effects inherent in displaying a line segment on a raster display having a matrix array of pixels, including the steps of:
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constructing a line segment of finite width; dividing said line segment into equal parallelogram-shaped line sections each having a short dimension one pixel in width and a long dimension orthogonal thereto; dividing the long dimension of each of said line sections into a proportionate number of one or more pixels; determining the percentage of the area of each pixel of each said section common to said line segment as would be displayed on the display; determining a brightness value for each pixel of each said section in proportion to its respective percentage of area common to said line segment; and activating said pixels in accordance with the above-determined brightness values to display said line segment on the raster display. - View Dependent Claims (11, 12)
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Specification