I am trying to write a php script that will (among other things), desaturate an image by 60% ( not all the way to greyscale )

I have been looking all over for an answer but cannot find one. I am pretty sure there is no built in functionality to do this in gd, so it would have to be a custom function, but i dont know the colour theory enough to program the math for it.

(I realize that this is a bit of a specific and obscure question, so even if you dont know the answer, if you could suggest a better place to ask for help (a PHP centric forum?), that would be appreciated too.)

Hi

I've never had that exact problem, but I've done some obscure image processing with PHP before. First, you cannot do much with gdlib. PHP is not good for pixel wise processing, so we need tools. Try this:

http://www.imagemagick.org/script/index.php

My advice is first to try to solve the problem on the command line. If it scales badly executing commands in the script, there is a PHP module. On my system it's called "php4-imagick".

Warning:
ImageMagick is progressing fast. So it tends to being incompatible with old versions. They forked into "GraphicsMagick" for that reason.