Every day in the Photo Lab we see photos with Red Eye in them, most often in photos taken at parties and other night time shots. Thankfully the kiosks which customers use to submit their orders do have an editing feature where the customer is offered the opportunity to remove any Red Eyes in an image.
Unfortunately however this feature is not particularly good and can lead to leaving black marks over people’s faces. Unfortunately this is because most filters work the same way, by detecting areas of bright red associated with Red Eyes, and trying to correct this by darkening the area. This can lead to someone with rosy cheeks (a common thing at a party) can fool the filter into thinking that these areas are in fact Red Eyes and leaving them with black marks over their faces.
Red Eye is caused by the light of the flash being too fast for the pupil to react to, so the pupil stays wide open when the flash is fired. The light from the flash enters the eye and reflects off the back of the eyeball before it travels back through the pupil before exiting the eye. The red colour that the camera detects is from the large quantity of blood in the eye behind the retina.
The best cure for red eye is to ensure that it does not occur in the first place, either by increasing the lighting in the room so that the pupils constrict and allow less light to enter the eye, or by using the red eye reduction feature built into most modern compact cameras. These red eye reduction features work by firing the flash three or four times before the photo is taken, this also causes the pupils to constrict and vastly reduces the red eye effect.
If you have a bounce flash for an SLR, aim it at a nearby pale surface so that the light bounces off this surface and illuminates the subject, or if you simply place the flash away from the camera so to the subject it is at a different angle from the camera. Both of these methods will cause the light from the flash to enter the eye at a different angle from the camera lens and thus be reflected out of the eye away from the camera lens, getting past the red eye problem.
Of course there is a much simpler solution available, have the subject look away from the camera.
The Red Eye effect can however be a good thing in certain circumstances. Leukocoria is an abnormal white reflection from the retina, instead of the usual Red Eye. This is can indicate cataracts and a whole host of other problems including Retinoblastoma in young children. Retinoblastoma is a cancer of the growing cells in the retina and affects mostly children under the age of five. In photos of young children spotting a white reflection in the eye early enough can mean the difference between effective treatment being administered and surgical removal of the eye. For more information on Retinoblastoma please take a look at The Childhood Eye Cancer Trust Website.
I hate that red eye removal tool. If it’s not leaving marks on people’s faces like you describe it appears as if it’s not doing anything at all. Of course, customers in general seem to be afraid of trying to do it manually, which is just as well because it’s a pretty slow and cumbersome process in itself.
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