Opensource Photoshop Clone: GIMP

http://www.gimp.org

GIMP (GNU Image Manipulation Program) is an image retouching and editing tool and is released under the LGPLv3 and later versions and the GPLv3 and later versions as free and open-source software. There are versions tailored for most operating systems including Linux, OS X, and Microsoft Windows.

GIMP has tools used for image retouching and editing, free-form drawing, resizing, cropping, photo-montages, converting between different image formats, and more specialized tasks. Animated images such as GIF and MPEG files can be created using an animation plugin.