GIMP - GIMP is a multiplatform photo manipulation tool.
ImageJ - and Other Health Care
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Image Pro - Used by researchers worldwide, Image-Pro Plus image processing software makes it easy to acquire images, count, measure and classify objects, and automate work.
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.
Fiji - Fiji: A batteries-included distribution of ImageJ.