We are all familiar with the dreaded Red Eye in photographs. Fortunately most photo editing applications (GIMP included) have a Red Eye tool built in. Unfortunately most work by detecting red and working from there and hence fall flat on their collective faces when confronted with the green eyes which photos of dogs and other pets can be afflicted with.
This was exactly what happened to me today, anyway after some trial and error I came up with this method, it may not be perfect but it might be of some use in those situations where conventional Red Eye tools fail. Another option of course would be to select the offending colour and minimise it’s effect using the Channel Mixer tool, but I find this to be finicky process and I normally only end up changing the colour rather than elimenating it.
This photo of Lal was taken shortly before she died, she was a diabetic and the cataracts, which are a very common symptom of the disease, have caused a particularly nasty green eye effect. In this case I started by opening my file in GIMP and…
1. Zoom in on one of the eyes and select the Fuzzy Select Tool from the Toolbox and click on the eye. You will need to adjust the Threshold value until the entire green area is selected, In this example I increased the Threshold to 100. One thing I like about this method is that it does not matter if any catch lights are selected.
2. There is normally a small rim of colour just outside the area we selected. We can enlarge the selected area slightly by going to the dropdown menus and selecting Select > Grow… In the resulting dialog box choose to grow the selection by 1 pixel and click OK (you may need to use more in some cases)
3. To get rid of colour select Colors > Desaturate… Choose a desaturation option and click OK. I have used the Lightness option in this case because it produced the darkest result.
4. Launch the Curves tool by selecting Colors > Curves… Then darken the selected area by using your mouse to grab the center of the curve and drag it down and to the right.
5. Use the Clone tool from the Toolbox to fix any odd reflections there may be in the eyes, in this case reflections from Lal’s cataracts. (This step will be unnecessary in the majority of cases).
6. The transition between the selected area and the rest of the image will often be too “hard”, select Select > Grow… and this time enlarge the selection area by 3-5 pixels (or whatever suits your image) then select OK.
7. To do the actual softening use a gaussian blur. Select Filter > Blur > Gaussian Blur… I used the default of 5, then select OK.
8. Your eye should now be done, turn off the selection with Select > None and repeat the process for the other eye.