Image format
What is a RAS file?
RAS (Sun Raster) is the native bitmap format of Sun Microsystems' SunOS/Solaris workstations from the 1980s and 90s.
Sun Raster was the default way SunOS and early Solaris systems stored screen captures and bitmap images, defined in Sun's own rasterfile.h header in 1989. A file opens with a fixed 32-byte header carrying its magic number, dimensions, and bit depth, optionally followed by a color palette and then the pixel data itself, either stored raw or run-length encoded. It supports 1-, 4-, 8-, 24-, and 32-bit depths but no transparency, and while it was genuinely common on Unix workstations in its day, it's now almost exclusively encountered when working with archived files from that era.
How to open a RAS file
RAS isn't something ordinary photo viewers or browsers open — it needs GIMP, IrfanView, ImageMagick.
Modern operating systems have no built-in viewer for RAS — a converter or an editor with RAS support is needed.
Strengths & limitations
Good for
- simple, well-documented header — easy for tools to parse
- supports both raw and RLE-compressed pixel data
Watch out for
- no transparency support
- obsolete outside legacy Unix/Solaris archives
Convert RAS files
Orbfile can convert RAS both ways, entirely in your browser — pick a direction below:
Frequently asked questions
What does a RAS file contain?+
RAS (Sun Raster) is the native bitmap format of Sun Microsystems' SunOS/Solaris workstations from the 1980s and 90s.
Can I convert RAS for free?+
Yes — Orbfile's image converter handles RAS for free, with no file limit, watermark, or account, and it runs entirely in your browser.
Is converting a RAS file safe and private?+
Yes. Orbfile processes RAS files locally on your device using WebAssembly — nothing is uploaded to a server, so there's nothing to leak or store.
Who created the RAS format?+
RAS was developed by Sun Microsystems, first released around 1989.
Browse the full file format guide.