Blastizer uses ImageMagick to convert contemporary image formats to the 4-bit Mega Drive/Genesis colourspace. It offers three filters to adjust the image: Floyd–Steinberg dithering, normalization and equalization. In addition to direct palette manipulation that will swap any color in the image for a choice of any of the 512 Mega Drive/Genesis colours.
ImageMagick7 development package (ImageMagick-devel), FLTK 1.4
On Linux, depending on your distro the package names may vary. However, at the time of writing, FLTK 1.4 is experimental and not officially released, and so it is advised to get the source at: https://github.com/fltk/fltk and compile it yourself.