GIMP is an open source tool with similar capabilities to Photoshop, for tasks like photo retouching, image editing, image authoring. Best of all, it’s free.
You can download GIMP at http://gimp-win.sourceforge.net/stable.html
A free plug-in is required edit eps files. Instructions for installing ghostscript can be found at http://www.werockyourweb.com/install-ghostscript-windows-and-gimp . Please note you only ghostscript is you want to edit eps files.
More info on gimp at gimp.org or via your favorite search engine