Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
GIMP - GIMP is a multiplatform photo manipulation tool.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
ACDSee - ACDSee is an image viewer that uses very little system resources, and it has a small, sleek size that won't take up much space on your system.
ShapeX - Collage - Free Shape-Collage Generator! – (v1.1) Save Example Images & New Examples !