I use
Adobe Photoshop (a highly user-friendly tool;-)) for all photo-editing work
Advantages:Photoshop can utilize the color models RGB, lab, CMYK, grayscale, binary bitmap, and duotone. Photoshop also has the ability to read and write raster and vector image formats such as: .EPS, .PNG, .GIF, .JPEG, Fireworks, etc.
I can still remember being intimidated by Photoshop's extensive features when I first started using it. But actually, learning Photoshop (and being good at it) is
very easy!;-) Yet, many find it easy to give up because like it or not, photo-editing is very tedious. You need tonnes of patience.