NEOchrome is an early color bitmap graphics editor for the Atari ST computer family. It was written by Dave Staugas, a programmer at Atari and co-author of the ST's operating system. NEOchrome allows hardware-supported color cycling to give the impression of animation. A color-cycling waterfall, created with NEOchrome, was one of the iconic images of the early Atari ST.
Following in the footsteps of MacPaint and the Apple II version which was renamed Mouse Paint, both released in 1984, NEOchrome uses the then-novel representation of painting tools by icons (in addition to other GUI elements).
An pre-release version (v0.5) was included with the system disks of the first STs. A proper version 1.0 arrived later, and was bundled with several versions of the ST. Although not officially public domain, this version was often treated as such, and was never actually sold. As a result of this, NEOchrome enjoyed a relatively high level of popularity within the ST community, even in the face of more advanced packages such as DEGAS Elite and Deluxe Paint.
NEOchrome Master was built by disassembling the binary program "NEOchrome 1.0". The resulting source code was uncommented and hard to read. But it could be assembled back into the same binary program as before. This allowed the author to extend the program.
Many extensions were built into the program and various version were released to the public.