Anyone who has taken a flash photo of their cat is aware of the cloudy yellow/green reflection in their eyes. Such was a topic of discussion on Flickr Technique.
The reason for this is that cat eyes have a reflective coating in the back of their eyes called the tapetum. Nocturnal animals have this so that light passes twice through the transparent rods/cones of their eyes creating a second opportunity to absorb the photos and resulting in better night vision—at the price of some acuity of vision because of the folded optical path. Light comes from two distances and cats are far-sighted anyways.
Pretty neat piece of evolutionary engineering.
Our eyes don’t have that, so in these cases you get a “red eye” as the flash reflects the back of the blood vessels in our eyes. Unfortunately red-eye tools don’t correct for this. The trick to fixing this is to use the old manual red-eye method:
- In your image editing application, select the area that is green (and only that area).
- Open up the Hue/Saturation panel and decrease the saturation of the cyan channel.
- You may also need to lower the lightness of the master or cyan channel lest the eyes appear too cloudy.
Anyone have a better post processing technique? This only works on shots where the eyes are far small dots.
Besides the obvious and defeatist, “don’t use flash” technique, another way to avoid this is the same way you would with “red eye”: bounce the flash or move the flash far from the camera lens (so that the main light doesn’t come from the same direction of the lens (and reflect back).
In any case, check out the Flickr discussion for some cases where the cat’s version of red-eye is actually sort of cool.