pamgradient - create a four-corner gradient PAM or PNM image
pamgradient [-maxval=maxval] color-tl color-tr color-bl color-br width
Minimum unique abbreviation of option is acceptable. You may use dou-
ble hyphens instead of single hyphen to denote options. You may use
white space in place of the equals sign to separate an option name
from its value.
This program is part of Netpbm.
pamgradient creates an image of the specified dimensions width by
height which contains a smooth, two-dimensional gradient between the
specified colors of the four corners (from top left to bottom right).
Specify the colors as described for the argument of the ppm_parsec-
olor() library routine .
If all four colors are gray values, pamgradient creates a grayscale
image (PAM tuple type GRAYSCALE). Otherwise, it creates a color image
(PAM tuple type RGB).
Only the top left corner of the generated image has exactly the speci-
fied color. The color of the top right corner is a bit shifted to the
left, the bottom left corner a bit up, and the bottom right corner
left and up. This ensures nice transitions when combining adjacent
(very narrow) gradients, and doesn't play a role when the gradient
butts against a solid surface.
This effect is created by the integer arithmetic used for the interpo-
lation of the color values, and since it doesn't make a difference for
all practical purposes I might as well sell it as a feature.
pamgradient was new in Netpbm 10.31 (December 2005).
pamgradient was written by Daniel Haude in October 2005.
netpbm documentation 21 October 2005 Pamgradient User Manual(0)