Using Masks and Layers—Painting, Filling, and Color Tools - GIMP 2.6 for Photographers: Image Editing with Open Source Software - page 174

3.2.2 Eliminating the Red-Eye Effect
Since GIMP 2.4, there is a filter to eliminate the red-eye effect. You'll find it
by choosing Filters > Enhance > Red Eye Removal . The filter is easy to use and
efficient. You can follow the steps as we go along. To do this exercise, open the
image redeyes.bmp in the SampleImages folder on the DVD and save it in your
exercise folder.
Figure 3.5
The Red Eye Removal window. To focus the effect of the filter, I selected the area around the red pupils with the Free
Select tool. Otherwise all red objects in the image would have been converted to grayscale colors.
After you choose the Red Eye Removal filter, a window opens with a
preview image in which the red pupils are already blackened. You can increase
the blackening by moving the Threshold slider to the right. To assist the filter,
you can use the Free Select tool ( Lasso ) to make a selection around the eyes.
That's it. Click OK. The result is quite convincing.