NEOchrome

NEOchrome is an early color bitmap graphics editor for the Atari ST. It was written by Dave Staugas, a programmer at Atari Corporation and co-author of the ST's operating system. "NEOchrome" supports 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).
A pre-release version (v0.5) was included with the system disks of the first STs. 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. NEOchrome enjoyed a relatively high level of popularity within the ST community, even in the face of more advanced packages such as DEGAS and Deluxe Paint.
NEOchrome Master.
Although there were no further official versions, an unofficial revision called NEOchrome Master was released by the Atari demo scene group Delta Force's Till Bubeck (programmer of The Return of Medusa) in the early 1990s.
NEOchrome Master was built by disassembling the binary program "NEOchrome 1.0". The resulting source code was uncommented and hard to read, but could be assembled back into the same binary program as before. This allowed the author to extend the program.