What are some alternatives?
GIMP - GIMP is a multiplatform photo manipulation tool.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.
PaintTool SAI - Learn to draw in different ways.
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
SpeedTree - SpeedTree is a powerful toolkit used to create 3D vegetation for video games, films, and animations.