Wednesday, July 6, 2011

Red Eye Removal in GIMP

Easy Tutorial for How to Remove Red Eye Using GIMP

Almost everyone who has ever taken a snap at a party or event in low light using their on-camera flash will be familiar with red eye. The phenomenon is caused by light from the flash being reflected from the blood vessels in the back of the eye and gives the pupils of those in the picture a bright red color that can look rather odd.

This problem can be easily corrected by using free pixel-based image editors such as GIMP. Because this is such a common problem, GIMP has the Red Eye Removal tool, found in the Filters menu, under Enhance, to quickly and easily eliminate the appearance of red eye.

1. To Prepare or Not to Prepare

Image showing red eye© Ian Pullen
You can use the Red Eye Removal tool without any other preparation, but if there are other areas of the picture containing shades of red, you may get surprising results. For that reason, if you have time I would advise you to select the areas you want to change first.

2. Select the Areas of Red Eye

Select red eye areas© Ian Pullen
To do this, select the Ellipse Select Tool from the Toolbox and draw a selection around the first area of red eye. You don't need to make an accurate selection, but ensure all of the red is included in the selection. Before selecting further areas, move to the Ellipse Select Options that are visible below the Toolbox and click on the Add to the current selection mode – it is the second of the four Mode buttons. You can now select more areas of red eye without removing your existing selections.

3. Select the Red Eye Removal Feature

The Red Eye Removal menu item© Ian Pullen
When all areas of red eye in the picture have been selected, you can go to the Filters menu, and select Red Eye Removal from the Enhance sub-menu to open the tool's dialog box.

4. Apply the Red Eye Correction

Apply the red eye removal tool© Ian Pullen
The dialog box will show a preview image that contains all of the areas that you have selected. (In my illustrated example, just two eyes.) You can use the zoom controls to look more closely at the preview to see the effect that the current settings will produce. If there are any signs of red around the edges of the pupil, you can slide the Threshold slider a little to the right until the red disappears. When you're happy with the preview, click OK.

5. Bye Bye Red Eye

Red eye removed© Ian Pullen
The changes are then applied to your image and the red eye is nothing more than a memory. The Red Eye Removal tool makes light work of this common problem with flash photography, even for users with little experience of using GIMP.


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