procedure PixInit: initialize pixel processing procedure PutPixel: write pixel
link putpixel
August 14, 1996; Gregg M. Townsend
Requires: Version 9 graphics
This file is in the public domain.
These procedures assist pixel-by-pixel image construction.
PutPixel(W, x, y, k) draws a single pixel after applying
dithering, color quantization, and
gamma correction.
PixInit(gamma, cquant, gquant, drandom)
initializes parameters for PutPixel().
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PutPixel([win,] x, y, colr) sets the pixel at (x,y) to the given color
after applying dithering, color quantization, and gamma correction.
It is designed for constructing images a pixel at a time. The window's
foreground color is left set to the adjusted color.
Colr can be any value acceptable to Fg. Mutable colors are not
dithered, quantized, or gamma-corrected.
PixInit(gamma, cquant, gquant, drandom) may be called before PutPixel
to establish non-default parameters. The default gamma value is 1.0
(that is, no correction beyond Icon's usual gamma correction).
cquant and gquant specify the number of color and grayscale quantization
steps; the defaults are 6 and 16 respectively. If gquant + cquant ^ 3
exceeds 256 there is a potential for running out of colors. drandom
is the fraction (0 to 1) of the dithering to be done randomly; the
default is zero.