Sketch - Professional digital design for Mac.
Splashroad Separation Studio - Quick and Easy Color/Shape Separation
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Rasterbator - Wall art from any image
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Posterizer - The rasterbator allows you to create posters larger than a standard page, using the tiled printing method. It will rasterize any image and output files that can be printed at home and reassemble to the original image.