(PHP 4, PHP 5, PHP 7)
imagegammacorrect — Apply a gamma correction to a GD image
imagegammacorrect ( resource $image , float $inputgamma , float $outputgamma ) : bool
Applies gamma correction to the given gd image given an input and an output gamma.
image
An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().
inputgamma
The input gamma.
outputgamma
The output gamma.
Returns true on success or false on failure.
Example #1 imagegammacorrect() usage
<?php
// Create image instance
$im = imagecreatefromgif('php.gif');
// Correct gamma, out = 1.537
imagegammacorrect($im, 1.0, 1.537);
// Save and free image
imagegif($im, './php_gamma_corrected.gif');
imagedestroy($im);
?>
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https://www.php.net/manual/en/function.imagegammacorrect.php