I came across a digital painting program called Krita Studio.
“Krita was made for the professional artist. Krita anticipates your needs, whether you are working on concept art, mattes, textures, game tiles, illustrations or comics. Krita supports your workflow, with image sizes up to 25.000 pixels wide, with support for layered Adobe® Photoshop® PSD files, with support for OpenEXR, for OpenColorIO and ICC, with channel depths from 8 bits to 32 bits, with color models from RGB to CMYK to L*a*b. Krita’s brush engines are a joy to use, too! ”