Camera white balance is markedly different between the 2 photos though (assuming the phone is lying on the same surface). Look at the background: in photo 1, background is white and phone screen is yellow. In photo 2, phone screen is white and background is yellow. Looks like camera took WB info from the background in photo 1 and the phone screen in photo 2. Not saying you're not seeing a shift in colour at an angle in real life, just that it's hard to get an accurate picture of it. Best way would probably be to set custom white balance on a camera that can do that (not sure if any of the 3rd party iOS camera apps can, or if you'd need a standalone camera) using a sheet of white paper then take your photos using that WB setting under the same lighting conditions.