Accurate control of contrast on microcomputer displays

Denis G. Pelli, Lan Zhang

Research output: Contribution to journalArticle

Abstract

Off-the-shelf microcomputers can now display arbitrary 8-bit images, but accurate control of these images requires dealing with several undesirable properties of real digital to analog converters (DACs) and analog video monitors. The limitations of DACs and video monitors are presented in the form of a model for their calibration and use in vision experiments. Low contrasts can be accurately rendered by summing a small accurate a.c. signal and a large less-accurate d.c. signal (Watson et al., 1986; Behavior Research, Method, Instrument and Computers, 18, 587-594). Exploiting that idea, this note presents an easy-to-build passive resistor network, a video attenuator, that combines the outputs of three 8-bit DACs to render low contrasts with 12-bit accuracy at the display. Measurements confirm the 12-bit accuracy.

Original languageEnglish (US)
Pages (from-to)1337-1350
Number of pages14
JournalVision research
Volume31
Issue number7-8
DOIs
StatePublished - 1991

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Keywords

  • Contrast
  • Microcomputer graphics
  • Monitor calibration
  • Video attenuator

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

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