SRF (Sony Raw File) was Sony's first raw format. Only two cameras wrote it: the Cyber-shot DSC-F828, announced in August 2003, and the DSC-V3 from late 2004. If you have SRF files today, they almost certainly come from an old photo archive or a backup CD of one of these cameras. Sony replaced SRF after two years, so modern software treats it as a legacy format and some programs no longer open it.
A short-lived format
The F828 was an ambitious bridge camera with a 2/3-inch 8 MP CCD and a fixed 28–200 mm equivalent zoom. In December 2005 the DSC-R1 brought a revised format, SR2. When Sony bought Konica Minolta's camera business and launched the Alpha DSLR-A100 in 2006, it switched to ARW, which all Sony cameras use to this day. Sony never published a specification for any of the three.
What makes SRF unusual
- Four colours instead of three. The F828 sensor used an RGBE filter: next to red, green and blue, a quarter of the photosites sat under an "emerald" filter meant to bring colour response closer to human vision. A raw converter therefore has to interpolate four colours, not the usual Bayer three. Sony dropped the idea after this camera.
- Encryption. The file is TIFF-based, but parts of Sony's maker notes and the key needed to read the sensor data are encrypted. Open-source raw decoders learned to decrypt it soon after the camera appeared.
- 12-bit data, no compression. Each value takes 16 bits on disk, so an F828 SRF file is about 16 MB, several times the size of the camera's best JPEG.
How to open SRF files today
The easiest route is a program that supports both the DSC-F828 and the DSC-V3: darktable and RawTherapee (free for Windows, macOS and Linux), or Windows Photos with the free Raw Image Extension from Microsoft Store. Adobe Camera Raw, and with it Lightroom and Photoshop, supports the F828 as well. If an old program refuses the file, Adobe DNG Converter turns SRF into DNG, which nearly every raw tool reads.
Common problems
SRF file won't open or shows strange colours
Programs that expect a three-colour Bayer sensor fail on the four-colour data or produce green or magenta casts. Use darktable, RawTherapee or Camera Raw.
An SRF file that is not a photo
The same extension is used by Garmin navigation units for vehicle icons: two images, each with 36 views of the car rotated by 10 degrees. They belong in the Garmin/Vehicles folder of the device. Our converter treats SRF as a Sony raw file and cannot read Garmin icons. The Netpbm tool srftopam can.
Converting SRF
For an archive of old photos it makes sense to convert SRF into something every program reads. Our converter develops the SRF data using the camera's white balance and automatic brightness, and saves JPG at quality 90, PNG or TIFF with 8 bits per channel in sRGB. For long-term storage keep the SRF files themselves, or DNG copies, which preserve the full 12-bit data. More on raw formats in general on the camera RAW page.
SRF at a glance
| Developer | Sony |
|---|---|
| Used | 2003–2005, DSC-F828 and DSC-V3 only |
| Successors | SR2 (DSC-R1, 2005), ARW (since 2006) |
| Based on | TIFF, partly encrypted |
| Data | 12 bits per photosite, uncompressed |
| Status | obsolete, readable in darktable, RawTherapee and Camera Raw |
Details: the community description of Sony raw formats and the Library of Congress overview of camera raw formats, which lists SRF as "Sony Raw Image".