I still had my I4 and retina ipad that displayed white normally. I used this image:
http://en.wikipedia.org/w/index.php?title=File:Color_icon_white.svg&page=1
Instead of 5 of the squares displaying white, light blue, and purple. All of them were yellowish. It was the best way to show the problem in the lighting conditions. The person helping me agreed 100% and swapped it out. I was prepared to still argue that apple using 3 different suppliers is not an excuse for faulty equipment. It just explains why it is yellow, not justifying it being yellow. Its complete bs anyone has to go through this. Color settings should just be a standard option in the devices.