Eliminating the Red Eye Effect

Since GIMP 2.4, there is a filter to eliminate the red-eye effect. You'll find it by choosing Filters > Enhance > Red Eye Removal. The filter is easy to use and efficient. You can follow the steps as we go along. To do this exercise, open the image redeyes.bmp in the SampleImages folder on the DVD and save it in your exercise folder.

Figure 3.5

The Red Eye Removal window. To focus the effect of the filter, I selected the area around the red pupils with the Free Select tool. Otherwise all red objects in the image would have been converted to grayscale colors.

Figure 3.5

The Red Eye Removal window. To focus the effect of the filter, I selected the area around the red pupils with the Free Select tool. Otherwise all red objects in the image would have been converted to grayscale colors.

After you choose the Red Eye Removal filter, a window opens with a preview image in which the red pupils are already blackened. You can increase the blackening by moving the Threshold slider to the right. To assist the filter, you can use the Free Select tool (Lasso) to make a selection around the eyes. That's it. Click OK. The result is quite convincing.

In our example image, you have to preselect the eyes, otherwise the reddish skin tone and the red objects in the photo would have been altered. Select the Free Select tool (Lasso) in the Toolbox. Then go to the tools settings. As a setting for Mode, select the second symbol from the left: Add to the current selection. Now you can roughly draw around the eyes while holding the left mouse button. Create four small selections in the picture. This localizes the filter's operational sphere. Now apply the filter - voila! Done.

As a last step you must, however, deselect your selection. Choose Select > None. Optionally, you can isolate your selection with help of the Elliptical Selection tool.

The Red Eye Removal filter didn't exist in versions of GIMP prior to 2.4. You can use the method used before the Red Eye Removal filter was introduced if the filter didn't have the desired effect. Here comes the description:

Use the Zoom tool to zoom in to the area of red in the eyes. It is important that you select only the red section of the pupil.

Prepare the picture by dragging out at least two guides from the rulers. Position them as tangents to the upper and left side of the pupil. Select the Ellipse tool from the Toolbox. Point at the crossing point of the tangents. Click and hold the left mouse button while dragging it diagonally from the top-left corner of your imagined rectangle around the pupil toward the lower-right corner of the rectangle. Now you have an ellipse around the pupil that is marked by a border of "marching ants". This defines the edge of your selection. You can also use the Lasso tool. It is quicker and easier but also a little imprecise.

You now have an active selection on your image. Your adjustments will modify only the actively selected area; the remainder of the image is mask-protected against changes

In this exercise, you want the selection to have a soft border, or feathering. Without feathering, the adjustments you make will have a sharp-edged border, and it will look as if someone cut out an object with a scissors and pasted it on. Feathering the edges of the object will create a more natural appearance. Use the Select > Feather menu item to access the feathering function. The Feather Edges dialog pops up. Enter a value of 10 pixels and click OK to accept your changes.

In the next step, remove the color saturation. Access the Colors > Desaturate menu item. It requires only one click to remove the color levels from your selected area. You should see only the gray values now.

Next, access the Colors > Brightness-Contrast menu item to correct the brightness and contrast according to your taste. Finally, use the Select > None menu item to deselect the area.

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  • Leah Naumann
    How to remove red eye effect on gimp on one eyes?
    6 months ago

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