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From: denis@cns.nyu.edu
Subject: video-toolbox-97-07-01-c.sit
The VideoToolbox is a collection of two hundred C subroutines and several
demo and utility programs that I and others have written to do visual
psychophysics with Macintosh computers. It is fully compatible with 680x0
and PowerPC Macs and with Metrowerks CodeWarrior and Symantec C
compilers. It's free and may not be sold without permission. It should be
useful to anyone who wants to present accurately specified visual stimuli
or use the Mac for psychometric experiments. The text file "Video synch"
discusses all the ways of synchronizing programs to video displays and
the many pitfalls to avoid. The TimeVideo application checks out the
timing of all video devices in anticipation of their use in critical
real-time applications, e.g. movies or lookup table animation. "Video
bugs" reports all known bugs uncovered by TimeVideo's testing of 56 video
cards and drivers. Low-level routines control video timing and lookup
tables, display real-time movies, and implement the luminance-control
algorithms suggested by Pelli and Zhang (1991). In particular,
CopyWindows (or CopyBitsQuickly) faithfully copies between on-screen and
off-screen windows (or bit/pixmaps), WindowToEPS saves an image to disk
as encapsulated PostScript, for later printing or incorporation into a
document, and SetEntriesQuickly and GDSetEntries load the screen's color
lookup table, all without any of QuickDraw's color translations.
NoisePdfFill.c quickly generates visual noise images whose pixels are
samples from a specified probability density function. High-level
routines help analyze psychophysical experiments (e.g. maximum-likelihood
fitting and graphing of psychometric data). Assign.c is a runtime C
interpreter for C assignment statements, which is useful for controlling
experiments and sharing calibration data. This collection has been
continually updated since 1991. More that one hundred colleagues
subscribe to the email distribution (see below), and have indicated that
they are using the software in their labs. Documentation is in the source
files themselves. Many of the routines are Mac-specific, but some very
useful routines, e.g. the luminance-control, statistics,
maximum-likelihood fitting algorithms, and the runtime interpreter are
written in Standard C and will work on any computer. Those wishing to
acknowledge use of the VideoToolbox software might cite:
Pelli, D. G. and Zhang, L. (1991) Accurate control of contrast on
microcomputer displays. Vision Research, 31, 1337-1350. Reprints are
available.
Pelli, D.G. (1997) The VideoToolbox software for visual psychophysics:
Transforming numbers into movies. Spatial Vision 10(4):437-442
Denis Pelli Professor of Psychology and Neural Science New York
University 6 Washington Place New York, NY 10003 denis@psych.nyu.edu
http://rajsky.psych.nyu.edu/VideoToolbox/