Reducing and Removing Red Eye in Flash Photography
Red-eye appearance occurs in the both human and animal eyes that lack tapetum lucidum (eye shine), consequently, there's no eye shine, while red-eye rarely occurs in animals that contain a tapetum lucidum. The red-eye appearance is a photographic phenomenon, not observed in nature. This red eye appearance mostly occurs in photographs that are captured in dark locations using a flash.
Donna and Sam with and without Red Eye
Mouse over the photo and see the red eye disappear in Donna
The Red hue comes from the reflected light of our retinas occurring when the surroundings are typically dark or poorly lit. And it's in this type of environment, the camera flash creates an excess of light to the eyes. The flash of light happens so quickly that the iris in the eye has too little time to shut the pupil. This results in light light being
focused to the retina located at the rear of the eye. The Retina is rich in blood, due to blood vessels nourishing the eye. This blood filled retina shows up as a red reflection, and this gets returned to the camera. And this is what creates the Red effect that's visible from the eyes in photographs. The more open the pupils are, all the more Red appearance that's reflected in your photographs.
This red-eye appearance is caused the hue of the fundus, coming from melanin, a pigment, mainly found in the RPE (retinal pigment epithelium).
Although RPE is black for many animals, RPE in humans is brown. Therefore red-eye appearance is more prominent in animals and humans with eyes of lighter color, particularly blue, grey and children's eyes. Within both of these groups, the eye tissues contain relatively smaller amounts of melanin. Pale eye, and children's eyes, the iris has less melanin to block stray light from going through it, and additionally the choroid and retina contain less melanin to soak up stray light that penetrates the eye. Melanin's role in red-eye is more clearly observed in animals having heterochromia (difference in coloration): only in the blue eye is the effect exhibited. This effect is even more
prevalent in animals and people having albinism. Every form of albinism involves malformed creation and or melanin deposition.
This red-eye appearance is quite often seen in photographs with children as children's eyes have quicker adaption to darkness: in dim light the pupils of a child enlarge quicker, plus an enlarged pupil draw attention to the red-eye appearance.
Cat with odd-eyes displays red-eye appearance on eye-shine only within its blue eye
There's no red-eye in either animal, with eye-shine only in the dog. Analogous effects, some in relation to red-eye, come of several types:
In numerous flash photos, even those lacking perceptible red-eye appearance, the pupil's of many animals display eye-shine. However eye-shine's an effect that's unrelated, animals having blue eyes can exhibit the red-eye appearance on top of eye-shine. Many eye diseases bring about a "white-eye appearance" instead of the predictable red-eye appearance as in Leukocoria. An associated look, red reflex, is observed in fundoscopy; however, unlike red-eye, it's not a photographic phenonumun. In photos recorded using passive infrared-sensitive (non-IR emitting) tools, the eyes (not just the pupils) typically appear extremely bright. This is not caused by reflection, but to emission of heat from the body in the appearance of infrared light.
Photography techniques for Reducing and Removing
Red-eye can be reduced in many of ways:
Use a bounce flash in by aiming the flash at a close by light colored surface like a wall or ceiling or at a photographic reflector. This changes both the flash direction and makes certain that diffused only flash light comes in contact with the eye.
Moving the flash out of the path of the optical axis the camera is on makes certain that the light coming from the flash reaches the eye from an indirect angle. The light then reaches the eye using a bearing removed from this optical axis the camera is on and is subsequently refocused from the eye back using the same axis. using this method, the retina is not discernible to the camera while the eyes will look natural.
Shoot photos without using flash by improving the ambient lighting. By Increasing the room's lighting, the subject's pupils become more constricted. The preference of professional photographers is ambient light or using indirect flash because the camera's red-eye reduction function doesn't always deter red eye, for instance, having the subject look at an object other than the camera, perhaps over the shoulder of the photographer.
However if your subjects look away in the course of the pre-flash. they will not appear natural having small pupils, and besides, direct lighting from anywhere near the camera lens produces unflattering photographs. If you insist on using direct flash, a general principle is to detach the flash from your lens by 20 percent of the distance from the camera to your subject. For instance, if your subject is 6 feet away, your flash unit should be a minimum of 4 inches distance from the lens.
Making the aperture of the lens larger, using a higher ISO, or lowering the shutter speed.
Post process the image digitally to intensify its brightness, or by pushing the development of the film to increase the perceived film speed
Use the red-eye reducing function included many newer cameras. This is typically a series of
brief, low-powered flashes, or a solid piercing brilliant light triggering contraction of the iris, coming before the actual flash.
Various computer digital image software editors have the capability to reduce red eye by inserting a touch of blue.
Many have gone so far as to automate the process, and have the capability to fix many images at the same time. Red-eye removing functions are also included in many widespread consumer software programs such as the Microsoft Vista Photo Gallery, the Apple iPhoto,
GIMP and the Google Picasa. The shortcomings of fully automated
software-red-eye-elimination is that they're only accurate approximately 75% of
Oct 7, 2011