What Is "Red Eye" -- and How Do I Fix It?

One of the most common problems for amateur digital photographers is "red eye." You know the effect: You shoot with a flash, and your subjects end up with glowing red eyes. Unless your friends or family members actually have glowing red eyes (in which case you have bigger problems than just a bad picture), you need to eliminate the effect to achieve a realistic photo.

Why People Have Red Eyes in Your Photos

The red eye effect results from the light from a camera's flash reflecting off the subject's retina. As a result, a trace (or more) of red appears in the eyes of the subject.

Even worse than red eye on people is red eye on animals, which is often green or yellow, not red. You get more of this effect when you photograph pets because animals' eyes reflect more light than those of humans, to enhance their night vision.

How to Avoid Red Eye

Whether we're talking humans or animals, the easiest way to avoid red eye is to not use your camera's flash; you'll seldom get red eye when shooting under natural light. You can also minimize red eye by using more ambient light in addition to your flash. The red eye effect can also be overcome by moving closer to your subject and positioning the camera a little off to the side. The more off-angle to the center of the eye you can get the flash, the less the effect.

Another solution is to use a different type of artificial lighting. If you're really into photographic gear, consider using a speed light separate from your camera, bounce flash or flood lights positioned off-angle to the subject. The goal is to light the subjects without sending a beam of light directly into the back of their eyes.

Many digital cameras offer a red-eye reduction feature, which fires a pre-flash red-eye reduction light about a second before the normal flash. This forces the subject's pupils to contract, which lessens the amount of light reflecting off the back of the eye. Although this feature doesn't totally eliminate red eye, it does serve to minimize the effect.

Fixing Red Eye in Your Digital Photos

Because red eye is such a common problem, most photo editing programs make it easy to fix. Look for a special "red eye" tool in your photo editing software. It's a fix so easy that just about anyone can do it, with little more than the click of a mouse.

For example, both Adobe Photoshop CS2 and Photoshop Elements feature an easy-to-use Red Eye Removal tool. Before you fix the red eye, however, it helps to zoom in on the area you want to edit. Use the Zoom tool to get the eye big enough to work with comfortably. Now you can select the Red Eye Removal tool. Position the cursor over the red area of the pupil and click once. That should remove the red. Repeat that step for each eye you need to fix.

And if the one-click approach doesn't remove all the red eye (which it sometimes doesn't), there's another technique you can use. With the Red Eye Removal tool selected, click and drag the cursor to draw a rectangle over the entire red area of the eye. When you release the mouse button, all the red should be gone.

Other photo editing programs, from Picasa to Paint Shop Pro, feature similar red eye tools that work in a similar fashion. You either click on a pupil to remove the red eye, or draw a box or circle around the red area. The red is replaced with a darker, more natural color, and your subjects will look a lot more human.

Michael Miller is a writer and commentator on technology and digital lifestyle topics.