PhotoFlare - Quick, simple but powerful Cross Platform image editor.
GIMP - GIMP is a multiplatform photo manipulation tool.
PixBuilder - Free Photo Editing Software for PC
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
PhotoDemon - Lightweight portable BSD licensed photo editor for Windows focused on performance and usability.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.