The Sun Raster format is the native bitmap format on the Sun UNIX platforms. It is a simple bitmap format with wide distribution, particularly in the UNIX world.
The default extension for Sun Raster files is RAS
Supporting Platforms and Applications
Sun OS and many UNIX based applications.
PMView can read Sun Raster files with 1..32 bits. Supported file types are Old (00h), Standard (01h), Byte-encoded (RLE) (02h), and RGB format (03h).