I have a php utility that allows me to "fix" images uploaded to my web site (rotate, lighten/darken). A lot of photos come in way to reddish, and I was wondering if anyone has found a way to affect color balance. I don't see any obvious way to use the GD filtering functions to do it. Don't be concerned about controlling it, I choose from a presentation of several versions of the changed images, so any color adjusting solution would just apply the changes in degrees and a human would make the final choice.
Image filter is your choice to present such image to the user and let him select the appropriate looking one. below is a sample from http://www.phpied.com/image-fun-with-php-part-2/
$image = imagecreatefrompng('nathalie.png');
imagefilter($image, IMG_FILTER_COLORIZE, 0, 100, 0);
imagepng($image, 'img_filter_colorize_0_100_0.png');
imagedestroy($image);
So you can present few images with added green, added blue, added red etc and let user to choose the correct image.