If I take a picture with blitz, the problem is red eye. To remove this effect, I try to use GIMP. After I open the image file, I click "Dodge/Burn Tool" on Toolbox. Then I choose Type "Burn" than "Dodge" and Range "Highlights" than "Midstones" or "Shadows". To play this tool, try to zoom the image and than click the red colour on every eyes. You can choose the size of the Brush.
