PHP imagecolorresolvealpha Function: Retrieve Color Index with Alpha

The imagecolorresolvealpha function in PHP's GD library returns the index of a color with a specified alpha value for a given image resource, providing either the exact color index or the closest possible alternative.

Parameters $image – an image resource created by functions such as imagecreatetruecolor(). $red, $green, $blue – integer values for the red, green, and blue components. $alpha – an integer between 0 and 127 representing the alpha channel.

Return value

Returns TRUE on success (the color index) or FALSE on failure.

Example

<?php
// Load an image
$im = imagecreatefromgif('phplogo.gif');

// Get closest colors from the image
$colors = array();
$colors[] = imagecolorresolvealpha($im, 255, 255, 255, 0);
$colors[] = imagecolorresolvealpha($im, 0, 0, 200, 127);

// Output
print_r($colors);
imagedestroy($im);
?>