The best thing is to avoid the flash to reflect from the eyes from the very beginning. Red-eye reduction works by having the flash shine a light into the eyes of the subject just prior to the flash/shutter event. This serves to cause the irises in the subject’s eyes to narrow down.

• Use your camera’s red-eye-reduction flash setting. Scroll through the flash settings until you find an icon that looks like an eye. This will tell the camera to emit a pre-flash that will cause your subjects’ pupils to constrict and help prevent the light from bouncing off the blood vessels at the back of the eyes.
• Turn up the lights. Bright lights have the same effect on your subject’s pupils as your camera’s red-eye-reduction setting and with the pupils less dilated, red-eye should be reduced.
• Shoot at an angle. If you angle your camera so that the flash doesn’t project directly onto your friends’ eyes, there’s no light to bounce back, and if the flash is pointed in the right direction, there’s no red-eye. Of course, if you have an off-camera flash, that’s even better since it sits higher above the lens than do most onboard light sources. Your friends will be relieved and so will you.

If it now has happened, clean it up in software. Photoshop is all you need to change the colours from red to the original colours. There are several methods and here is one! Maybe not the fastest but the one which keeps structure of the pupil, and the white light reflexes in the eye intact. If one can say so? If none of the other methods work to eliminate your friends’ demon eyes, there’s still hope. All image-editing programs have a red-eye-removal feature that provides one-click fixes. Generally, all you have to do is select the red-eye tool, click on the center of your subject’s eye, and before you can say Rosemary’s baby, the red is gone.

1. Open the channel palette and look for the best pupil (in this case the darkest).Most likely it will be the Green channel. Definitely not the red channel in this case.
2. Use the elliptical marquee tool from the toolbox to select one of the pupils. Hold down the Shift to select the second pupil according to the picture just below.
3. With the elliptical marquee tool selected select now Anti-aliased in the Marquee Options palette to define a smooth edge. Enter value 1 for the Feather Radius value to softening the edges of the selection.
   Tips: Save the selection (by clicking on the save selection icon in the channel palette) as an alpha-channel. If you later on want to adjust something it is very easy to activate it again.)
4. Copy now the selected pupils when you are in the green channel only. With the selections still active, click on the red channel and choose Edit > Paste into, from the top main menu of Photoshop. What we do is that we copy the ” good” pupil from the green channel into the “bad” one in the red channel.
5. Activate now the blue channel and repeat the command “Paste Into”
6. Click now on the RGB-channel. Like magic!