PHP imagecolormatch Function: Matching Palette Colors to True‑Color Images

PHP provides the imagecolormatch function to adjust the colors of a palette‑based image so that they more closely match those of a true‑color image.

Signature: bool imagecolormatch(resource $image1, resource $image2) Parameters:

$image1 – a true‑color image resource.

$image2 – a palette image resource that must have the same dimensions as $image1.

Return value: Returns TRUE on success or FALSE on failure.

Example usage:

<?php
// Setup the true color and palette images
$im1 = imagecreatefrompng('./gdlogo.png');
$im2 = imagecreate(imagesx($im1), imagesy($im1));

// Add some colors to $im2
$colors = Array();
$colors[] = imagecolorallocate($im2, 255, 36, 74);
$colors[] = imagecolorallocate($im2, 40, 0, 240);
$colors[] = imagecolorallocate($im2, 82, 100, 255);
$colors[] = imagecolorallocate($im2, 84, 63, 44);

// Match these colors with the true color image
imagecolormatch($im1, $im2);

// Free from memory
imagedestroy($im1);
imagedestroy($im2);
?>

This example creates a true‑color image and a same‑size palette image, allocates several colors to the palette image, calls imagecolormatch to align the colors, and finally releases the resources.