What Causes Bright Red Eyes In Photos?

Picture this: You take the picture of a lifetime and review it only to realize that your eye are glowing a bright demonic red. 😱

No, nothing is wrong with your eyes. No, nothing is wrong with your camera either. And fortunately modern image processing and/or apps have gotten quite good at eliminating it.

Photographers have known for years that adding a detached flash to their camera can prevent most red eye. Newer cameras with integrated flash often flash the light briefly before taking a photo to keep away the red glows. Let’s look at why these work to fix red eyes in photos.

In the back of your eye, your retina is actually the color red. In fact, when you are seeing the bright red orbs in photos, you are seeing reflection of light off your retina!

Let’s have you try an experiment. Take a flashlight and shine it in someones eye. Try to see if you can get the eyes to light up red. Chances are it will be hard for you to get it to work. No, it’s not that they don’t have a retina or their retina isn’t red, it’s because your view through their eye is different from the view from the flashlight. If you could look in the same direction as the flashlight, you would be able to get that red light reflex. This is how cameras with detached lights prevent the red eye from appearing.

But how do cameras that have lights close to the lens work? The camera flash in this case is close enough to cause that red eye. The simple answer is that the more dilated the eye is, the brighter the red glow. If you could make the pupil smaller, such as by shining light a bit before the picture is taken, then bright red eyes can be reduced. Magic!

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