Add more sophisticated editing tools such as cloning tools, various brush sizes and masking tools

These would be very useful when deciding on what parts of an image needs finer adjustment, for example you may want to keep some shadows unchanged when increasing the brightness, but still want to get rid of other shadows or at least lighten them. The masking tools would enable you to accomplish this.

The cloning tool would enable you to get rid of blemishes or other intrusions on the images; for example, say you had a gorgeous beach image, but what's spoiling it is several people in the background; with the cloning tool you'd be able to cover them over with cloned sand and create a much better image.