GIMP is an Open Source Graphic Design and Image Retouch Software. It is one of the best alternative of Adobe Photoshop which can be used entirely free.
GIMP has very advance features which comes in handy only when you know these curves and its function completely.
I try to edit my images with GIMP and it's turned into a great picture.
There are various format's of editing images. It also support RAW image processing. RAW is the most recent and advanced image file format in which picture quality is a great deal.
Minimum 4GB of RAM is required to run GIMP with few hiccups and with 8GB or more RAM it works fine.
I am really surprised with the performance of GIMP which is quite exceptional. The quality of my retouched images looks much better than the Original One on any size of screen.
It is a good choice to use all image editing features for free whereas many other Software charges months fee.
I recommend this software for only professional Photo Editor. For beginners, this software is never going to be your best choice.
To use full potential of GIMP, you need to learn important curves and shortcuts and you have to invest time to be a professional Image Editor.