Can I swap colors in image using GD library in PHP?

Question

I got the image like this (it\'s a graph):

_{(source: kitconet.com)}

I want to change the colours, so the white is black, the graph line is li

Answer 1

IMG_FILTER_NEGATE: Reverses all colors of the image.

http://www.php.net/manual/en/function.imagefilter.php

Could that be a solution?