Enhanced Simplex (or is it Enhance Simplex?) (ESM) is a raster graphics format. It is possibly associated with the TMS Cranach Studio or TMS Cranach Paint graphics software for Atari ST computers.
ESM files apparently begin with the signature
'T' 'M' 'S' 0x00.
- Atari ST Plus Picture Viewer (2014 archive)
- Rest7 Online Image Converter