Fujitsu Laboratories developed a system for measuring skin color accurately. It uses a smartphone’s camera and a Color Frame to measure skin condition, including spots, dullness, and pore size. Watch this video.
Personally, I think using the frame is a good way to see the difference in the skin tone. It is not every time that you can have the same white balance on the camera. The standard frame will allow the app to adjust correctly (I think).
Watch the video.