One of the most common problems in photography is the demonic transformation of the Red Eye effect. It comes from using a flash in a dimly lit area. Since the subject’s pupils are wide open, there’s nothing to prevent the light from the flash travelling all the way to the far back of the eye. It bounces off the retina, picking up the signature reddish tint along the way, and returns to the camera. Presto, instant demonic possession. Dogs, cats, parakeets–even spiders–are all targets of this strange demon that seems to only haunt portraits.
Some cameras have an added red-eye reduction mode, though their solution seems a bit strange. When this camera mode is turned on, there are not one but two flashes for each picture. The first one is a pre-flash, half a second before the real one. The point of the pre-flash is to trigger the pupils to shrink, reducing the chance for red-eye. Unfortunately, it doesn’t eliminate red-eye, it just tries to lessen it. And worse, if the subjects don’t know about the pre-flash, there’s a chance they’ll blink or turn away between flashes because they’ll think the picture has now been taken.
Once red-eye gets past the camera lens, your only real option is to try to correct it with your photo editing program. Without a program or filter specifically designed to correct red-eye, you’ll have to fix it by hand, by zooming in until the red-eye effect almost fills the screen, and then painting it away, pixel by pixel. If you’re lucky enough to have a red-eye correction button, then fixing red-eye is often as easy as clicking on the outside of the pupil and hitting the Go button. The program will insert a circle that’s mostly black into the area covered with demonic red eyes.