How To Fix Cat Green Eye On Flash Photos With GIMP

When taking photos of pets such as dogs and cats using the flash on your camera, you will often find that the pet's eyes are left a strange glowing green or other colour. This is caused by the same problem as red-eye when you take photos of people. It is because the flash light bounces off the cat's retina and reflects the green colour back to the camera. The red-eye effect in people can be reduced by using the red-eye reduction feature on your camera, but this doesn't really work with pets. Ways of curing the problem in the first place include diffusing the light from the flash, moving the flash away from the camera, or pointing the flash away from the cat's eyes. (You may also find you have a red-eye reducing feature in your graphics editing software, but again, this doesn't work with green-eyes.)

However, you might have already taken the photos, or don't have the option of using the methods above. Here is how to fix cat green-eye using GIMP. GIMP is an excellent powerful free graphics editing program. You can download it for free (search on Google), or use a similar procedure with your other chosen graphics program, such as Photoshop.

Fixing Green Eyes With GIMP

Here is the original example photo with bright green eyes.

Original green-eye cat example

Firstly, zoom in so you have a big view of one of the cat's eyes. Select the "Free Select lasso tool" by pressing F. Select the whole of the cat's pupil by repeatedly click the mouse at various points around the edge. When you get back to your starting point, the selection will join up and you will be left with marching ants around the pupil.

Cat green-eye selection

Now, scroll across to the other eye, hold down the shift key and click a starting point on the edge of the other pupil. Again, work round the edge of the pupil, clicking the mouse until the selection joins up and you are left with both pupils selected.

Now, desaturate with "Colours" -> "Desaturate".

Desaturate cat green eyes to grey scale

If at this point you can see slight bits of green bleeding over the edges of your selection, feather the selection by "Select" -> "Feather", and feather by say, 5 or 10 pixels, then desaturate again. Experiment with that. Once you've done that, enter "Quick Mask" mode (Shift Q), then "Colours" -> "Threshold", press OK, then Shift Q again to turn the quick mask off. This will restore the feathered selection.

Select the Dodge and Burn tool (Shift D), and select the "Burn" and "Shadows" options in the toolbox. Now, paint across the pupils with the mouse kept pressed button down. You will see the pupils darken. If you want, darken the eyes further by doing this again.

Burn shadows to darken eyes

Green Eyes Fixed!

And here is the finished result.

Fixed cat green eye example
Page Updated 02/01/10