(PHP 4, PHP 5, PHP 7, PHP 8)
imagegammacorrect — Apply a gamma correction to a GD image
   Applies gamma correction to the given gd image 
   given an input and an output gamma.
  
imageA GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
input_gammaThe input gamma.
output_gammaThe output gamma.
| Version | Description | 
|---|---|
| 8.0.0 | imageexpects a GdImage
  instance now; previously, a validgdresource was expected. | 
Example #1 imagegammacorrect() usage
<?php
// Create image instance
$im = imagecreatefromgif('php.gif');
// Correct gamma, out = 1.537
imagegammacorrect($im, 1.0, 1.537);
// Save
imagegif($im, './php_gamma_corrected.gif');
?>