Depending on your computer's operating system and installed software, you should be able to do basic photo editing.

As I previously posted, they allow you to increase apparent illumination in shadowed areas, so you can salvage poorly exposed photos that cannot be easily re-shot using the correct shutter speed/aperture combination for lighting conditions.

"There's more to optics than meets the eye."--anon

"...most of us would be better off losing half a pound around the waist than half a pound on our rifle."--dhg