Digital Photo Management In Linux, Part 2 - page 3
The basic fixes we learned today apply to the entire image; you can't select a region of your photo and work only on that. You'll need a more deluxe image editor for that sort of fine-tuning.
That wraps up our two-part introduction to Digikam. Be sure to read the Digikam manual and visit the user's mailing list. Watch this space for future amazing digital photo editing howtos.