imagegammacorrect — Changes gamma values in an image.
int imagegammacorrect(image, original, new);
int image: Image
int original: Original gamma
int new: New gamma
Changes the brightness/contrast, or "gamma," in an image.
Values can be either negative or positive, and the image
will become darker or lighter, respectively. By changing
the original value, you can alter which parts of the
image are affected. When using dynamically created
pictures or altering existing pictures, altering the
gamma to a setting of 2.2 can be useful, as images at
this gamma setting have a similar brightness and contrast
on Windows and Macintosh platforms.
Example 423. Lighten an
$im = imagecreatefrompng("test_image.png");
imagegammacorrect($im, 1.0, 5.0);
PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing
(Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch).
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