Tutorial: Removing Red Eye from Digital Images

Red Eye Removal

"Red eye" results from the use of a flash reflecting off of the pupil of a person or animal. Flashes on compact digital cameras are particularly susceptible to this effect because the flashes are not terribly sophisticated and they are located very close to the lens on these cameras. The close proximity of the flash to the lens makes direct reflections from the pupil to the lens more likely. Here is an example image showing red eye:

This tutorial will show you a simple method to remove red eye from your digital photos. This tutorial uses basic tools and techniques available in nearly every photo editor, though we will use Photoshop as an example.

Start by making a copy of the original image file. This is always a good practice so you don't modify the original image, allowing you to easily restart at anytime.

Next, select only the portion of the eye that we want to correct. An easy way to do this is to use the "elliptic marquee tool" (in Photoshop, hotkey M). After you select the area using the marquee tool, "feather" the selection to soften the edges (Select->Feather...). A feather value of 15 or so should work, but may need to be higher or lower depending on the size of your picture. This feathering helps to avoid sharp edges being created in the subsequent steps.

Red portion selected using the marquee tool	Adjusting the red channel in using Levels	The pupil after use of the levels tool

Now that you have the troublesome area of the eye selected, you can adjust the color of the selected area. The next step will act only on the area that we selected. To make it easier to see what is going on, however, we will "hide" the selection boundary (View->Show->Selection Edges, or Ctrl-H). Pull up the levels tool (Image->Adjustments->Levels..., or Ctrl-L). (Please note that we did not hide the selection in the images shown here.) Select the "Red" channel from the drop down at the top of the Levels dialog. Slide the black arrow on the left all the way to the right side, as shown in the figure. Select the "Green" channel and slide the middle gray arrow to the right some, and do the same for the "Blue" channel. This will deepen the blacks in the pupil. Click "OK" to close the dialog.

That's it for the basic adjustment!

Some people like to do another couple of steps to make the eye look as natural as possible. Next, we will use the "Hue/Saturation" tool (Image->Adjustment->Hue/Saturation..., or Crtl+U), and slide the saturation arrow to the left (toward -100). This will remove the color from the selected area. Click "OK" to close the dialog when you are happy with the result.

In this sample picture there is highlight in the middle of the eye that sticks out because of the harsh, sharp edge. When this happens, zoom in on the problematic area and use the blur tool to blur it away.

Red Eye Before Correction	Eye after correction for red eye

Photoshop and many other photo editing software packages have dedicated red-eye removal tools. Feel free to experiment with this tool, too. It sometimes works great, but often falls short. As with almost everything you might do in Photoshop, there are other ways to achieve the same goals. A simple web search for "red eye removal" will reveal many other techniques. Knowing a "manual" procedure like the one outlined here can be a real lifesaver when you need to rescue an important image.