Red-eye effect

The red-eye effect in photography is the common appearance of red pupils in color photographs of human eyes.

[3][4][5][6] The main cause of the red color is the ample amount of blood in the choroid, which supports the back of the eye and lies behind the retina.

[8] Digital cameras with red-eye correction can eliminate the effect by using flash lighting that fires rapidly and repeatedly just before a photograph is taken, which causes the subject's pupils to contract.

Following the detection of the subject's face and eyes, the algorithm searches for red-eye regions, which are subsequently enlarged using the region-growing technique.

[10] Computer scientists Xiao-Ping Miao and Terence Sim have proposed their technique for detecting red-eye by fusing subjects' flash and non-flash photos.

[11] Scholars Tauseef Ali, Asif Khan, and Intaek Kim put forth an algorithm that, following facial recognition, grayscales the image before applying red-eye correction.

[12] On the contrary, researchers Richard Youmaran and Andy Adler presented a method for improving the quality of videos with the red-eye phenomenon.