The ORF file (.orf)

ORF is the raw format of Olympus digital cameras, including the Four Thirds E-series SLRs, the OM-D and PEN Micro Four Thirds cameras, and since 2022 the OM System cameras such as the OM-1. When the camera is set to RAW (or RAW + JPEG), each photo is saved as an .orf file.

Like all raw formats, it holds one value per photosite, measured behind a red, green or blue filter, before the camera demosaics it into colour pixels, sets the white balance, applies its picture mode or Art Filter and makes a JPEG. In an ORF all of that is stored as settings, which raw software applies, or overrides, later.

• 12 bits per photosite: 4,096 levels, against 256 per channel in an 8-bit JPG. Current cameras store them with lossless compression; Imaging Resource's OM-1 specification lists "12-bit lossless compressed RAW (.ORF)".
• It looks flatter than the camera's JPEG when an editor opens it with neutral settings.
• Art Filters are only settings. They show in the camera's preview JPEG; most third-party raw editors ignore them. OM Workspace can apply them.
• Not for sharing. Browsers can't display ORF. Export a JPG or HEIF for that.

On 1 January 2021, Olympus transferred its camera business to OM Digital Solutions, a new company 95% owned by a subsidiary of the private equity firm Japan Industrial Partners, with Olympus keeping 5%. The first camera released by the new company, the PEN E-P7 in June 2021, still carried the Olympus name. In February 2022 the OM System OM-1 launched the new brand.

For users little changed: the files keep their extension and structure, and raw software supports each new camera model as it appears. The different maker-note header is mainly a concern for metadata tools, which had to learn the new signature.

Many OM-D and OM System cameras have a High Res Shot mode: the camera moves its sensor between several exposures and combines them into one image with far more pixels than the sensor has. On the OM-1, Imaging Resource lists an 80-megapixel composite from a 20-megapixel sensor. In raw mode the camera saves the combined result as an ORF.

• OM Workspace (Windows and macOS, from OM System's download site, which asks for a camera serial number): OM System's viewer and raw editor, the successor to Olympus Workspace. It applies the camera's own picture modes and Art Filters, has AI noise reduction for supported cameras, and with some cameras can use the camera's processor over USB (USB RAW processing) for faster conversion.
• Adobe Lightroom, Lightroom Classic and Photoshop (Camera Raw), Capture One, DxO PhotoLab and Affinity Photo all read ORF.
• Free and open source: darktable and RawTherapee on Windows, macOS and Linux.
• Just looking: Photos and Preview on a Mac, for cameras on Apple's supported list; Windows Photos with Microsoft's free Raw Image Extension.
• In the camera: the playback menu's raw data edit option saves a JPEG copy with new settings.

# check the signature: expect "IIRO", "IIRS" or "MMOR"
head -c 4 P1010001.ORF; echo

# save the embedded JPEG preview
exiftool -b -PreviewImage P1010001.ORF > P1010001.jpg

# render the raw data with darktable
darktable-cli P1010001.ORF P1010001.jpg

For older software that doesn't know a newer camera, Adobe's free DNG Converter makes DNG copies that older Lightroom and Photoshop versions open.

• The camera is newer than your software. Every new model has to be added. Update, or convert with Adobe DNG Converter.
• It's a High Res Shot file. Some apps open normal ORFs from a camera but not its High Res Shot files. Use OM Workspace or an up-to-date Lightroom.
• A TIFF tool calls it corrupt. It is checking for the TIFF magic number 42 and finding RO or RS. The file is fine; use a raw converter.
• Art Filter or picture mode missing. Third-party editors develop the raw data with their own settings. Apply the look in OM Workspace, or use the camera's JPEG.
• Colours differ from the camera. Choose a camera-matching profile in your editor, or develop in OM Workspace.

Shoot ORF when you plan to edit or the light is difficult: white balance and exposure can be changed far more than in a JPEG. For quick sharing, RAW + JPEG keeps a ready-made copy.

An ORF can't run code, but its Exif data and maker notes record a lot:

• Body and lens serial numbers in the Equipment directory, linking every photo to your gear.
• Location, if the camera took it from a phone app or has GPS.
• Copyright and author text set in the camera menu, plus dates and every setting.

Check with exiftool -a -G1 photo.orf, and remove GPS with exiftool -gps:all= photo.orf. Don't strip all maker notes from the raw file itself, since converters need them; share an exported JPEG with metadata removed when privacy matters.