<?php
function InvertColors($image) {
$im = imagecreatefrompng($image);
list($width, $height, $null,$null) = getimagesize($image);
for($y=0;$y<=$height;$y++) {
for($x=0;$x<=$width;$x++) {
$color = imagecolorsforindex($im,imagecolorat($im,$x,$y));
imagesetpixel($im,$x,$y,imagecolorallocate($im,255-$color['red'],255-$color['green'],255-$color['blue']));
}
}
imagepng($im);
}
InvertColors('image.png');