What is the RF file format?
.rf is an uncommon extension for the Sun Raster image format - a binary raster image format developed by Sun Microsystems for its SunOS workstations. The canonical extension for Sun Raster files is .ras; .rf, .sun, and .sr are alternate extensions for the identical format.
A Sun Raster file begins with a fixed 32-byte header identified by the magic number 0x59A66A95 (big-endian) at byte offset 0. The header encodes image width, height, color depth, data length, image type, and color map information. Pixel data follows an optional color map and is row-padded to 16-bit boundaries.
The format supports several image types: standard uncompressed, run-length encoded (RT_BYTE_ENCODED), 24-bit RGB, and experimental variants. Color depths range from 1-bit monochrome to 24-bit true color, with an optional 8-bit alpha channel at 32 bpp.
Sun Raster was the native screen-capture and image exchange format for SunOS and later Solaris. It was superseded by PNG and TIFF well before Oracle's acquisition of Sun in 2010. Modern image tools such as GIMP, IrfanView, and ImageMagick retain legacy read support.
Security & safety
RISK: LOWSun Raster is a pure raster image format with no scripting or embedded executable code. Safe to open in any image viewer. The format is so obsolete that it is not a malware vector.
Format details
in a nutshell- RealFlash Clip - RealNetworks used .rf for RealFlash (vector animation, Flash-like) clips in late 1990s RealPlayer versions; obsolete since RealPlayer dropped Flash support.
- Autodesk Land Desktop Rainfall Frequency Data - Autodesk Land Desktop used .rf for hydrology rainfall frequency data tables; format is proprietary ASCII/binary data, unrelated to raster images.
Programs that open RF files
Windows3 apps
GIMP
Open-source File > Open, select .rf file. GIMP recognizes the Sun Raster magic bytes regardless of extension. 
IrfanView
Free Open directly; IrfanView supports Sun Raster (.ras). If .rf is not recognized, rename to .ras first. 
macOS1 app
Linux2 apps
Technical details
deep spec| Magic number | `0x59A66A95` (big-endian) at byte offset 0 |
| Byte order | Big-endian |
| Header size | 32 bytes (fixed) |
| Supported color depths | 1, 8, 24, 32 bpp |
| Image types | 0=old, 1=standard, 2=RLE byte-encoded, 3=RGB, 4=TIFF, 5=IFF, 0xFFFF=experimental |
| Compression | None (type 1) or byte-run RLE (type 2) |
| Row alignment | Pixel rows padded to 16-bit (2-byte) boundaries |
| Color map | Optional; stored between header and pixel data |
| Alpha channel | 8-bit supported via 32 bpp mode |
| Canonical extension | `.ras` (`.rf`, `.sun`, `.sr` are alternates) |
| Associated OS | SunOS, Solaris |
| Released | ~1982 (SunOS 1.0 era) |
| Specification | www.fileformat.info |
RF conversions
Community Q&A
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