“Filtering edges for gray-scale displays” by Gupta and Sproull

  • ©Satish Gupta and Robert F. Sproull

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    Filtering edges for gray-scale displays

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Abstract:


    While simple line-drawing techniques produce “jagged” lines on raster images, more complex anti-aliasing, or filtering, techniques use gray-scale to give the appearance of smooth lines and edges. Unfortunately, these techniques are not frequently used because filtering is thought to require considerable computation. This paper presents a simple algorithm that can be used to draw filtered lines; the inner loop is a variant of the Bresenham point-plotting algorithm. The algorithm uses table lookup to reduce the computation required for filtering. Simple variations of the algorithm can be used to draw lines with different thicknesses and to smooth edges of polygons.

References:


    1. Bresenham, J. E. Algorithm for computer control of a digital plotter. IBM Systems Journal 4(1):25-30, July, 1965.
    2. Crow, F. C. The aliasing problem in computer-generated shaded images. Comm. ACM 20:799-805, Nov., 1977.
    3. Feibush, Eliot A., Levoy, Mark, and Cook, Robert L. Synthetic Texturing Using Digital Filters. Computer Graphics 14(3):294-301, July, 1980.
    4. Leler, William J. Human Vision, Anti-aliasing, and the Cheap 4000 Line Display. Computer Graphics 14(3):308-313, July, 1980.
    5. Pitteway, M. L. V. and Watkinson, D. J. Bresenham’s Algorithm with Grey Scale. CACM 23(11):625-626, November, 1980.
    6. Sproull Robert F. Using Program Transformations to Derive Line-Drawing Algorithms. Technical Report, Carnegie-Mellon University, Computer Science Department, 1981.
    7. Warnock John E. The Display of Characters Using Gray Level Sample Arrays. Computer Graphics 14(3):302-307, July, 1980.


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