File extension
.ras
Sun Rasterfile Format
.ras files are Sun Rasterfile images: the native raster format of Sun workstations, storing palettized or RGB images with an optional simple run-length compression.
Known meanings
Formats and reference material for .ras
Details
Format notes
Sun Rasterfile (RAS)
The Sun Rasterfile format was the native raster image format on Sun Microsystems’ workstations and SunOS/Solaris, and it became a common interchange format in Unix image toolchains of that era. It is a straightforward format: a fixed header followed by an optional color map and the pixel data.
The header begins with the magic number 0x59A66A95 and records the image width,
height, depth (bits per pixel), the length of the pixel data, a type field
indicating the encoding, and the color-map type and length. Images can be 1-, 8-,
24-, or 32-bit, and the type field selects between uncompressed data and a simple
byte-oriented run-length encoding. Multibyte values are stored big-endian,
reflecting the format’s origins on big-endian hardware.
Status And Preservation Notes
Sun Rasterfile is a legacy format, encountered mainly in older Unix imagery and
supported by classic tools such as Netpbm and ImageMagick. It is lossless and
documented, so it preserves image data faithfully; migrating to PNG or TIFF while
retaining the original is a reasonable preservation step. The common media type is
image/x-sun-raster.
Security Notes
As a binary format with an optional RLE mode and offset-driven color map, a reader should validate the declared dimensions, depth, and data length from untrusted files and bound the decoded output to guard against overflows.
Further Reading
- Sun Rasterfile format overview:
https://www.fileformat.info/format/sunraster/egff.htm