“The use of grayscale for improved raster display of vectors and characters” by Crow

  • ©Franklin (Frank) C. Crow




    The use of grayscale for improved raster display of vectors and characters



    Decreasing memory costs will soon allow grayscale displays in low-cost raster graphic terminals. Subtle shadings can be used to provide improvements in line quality and character flexibility which could allow raster displays to compete on better terms with the more expensive calligraphic displays. Algorithms for achieving smooth vectors and rotatable dot matrix characters are outlined and scan conversion is discussed. A discussion of the relation between image quality and number and distribution of gray levels follows, with concluding remarks on costs and other practical matters.


    1. Newman, W. M., “Trends in Graphic Display Design”, IEEE-TC, Dec. 1976
    2. Newman, W. M., 2648A Graphics Terminal, Hewlett-Packard, Palo Alto, California
    3. Newman, W. M., 4025 Terminal, Tektronix Inc. Beaverton, Oregon
    4. Newman, W. M., IGT 100 Interactive Graphics Terminal, California Computer Products Inc., Anaheim, California.
    5. Crow, F. C., “The Aliasing Problem in Computer-Synthesized Shaded Images,” CACM, November 1977.
    6. Shoup, R. G., “Some Quanization Effects in Digitally-Generated Pictures”, SID 1973 Symposium Digest of Technical Papers, May 1973.
    7. Davis, S., Computer Data Displays, 1969, Prentice-Hall, Englewood Cliffs, New Jersey.
    8. Newman, W. M. and Sproull, R. F., Principles of Interactive Computer Graphics, 1973, McGraw-Hill Inc.
    9. Biberman, L. M., ed., Perception of Displayed Information, 1973, Plenum Press, New York
    10. Cornsweet, T. N., Visual Perception, 1970, Academic Press, New York.
    11. Blackwell, H. R., “Contrast Thresholds of the Human Eye”, Journal of the Optical Society of America, 1946, Vol. 36, pp 642-643.
    12. Graham, C. H. ed., Vision and Visual Perception, 1975, John Wiley and Sons, New York.

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