Understanding Red-Eye in photos and how it can be prevented Why are eyes red in photos? Red-eye is a phenomenon that happens only when taking photos using a flash. When taking photos in day light or when in high ambient light scenarios peoples eyes look normal. When taking pictures in low ambient light scenarios using a flash the result many times is redness in the peoples eyes https://xn--bp2bm1qvxl.cc/%ec%9e%91%ec%97%85%ec%9d%b8%ec%a6%9d/