DNG to ORF Converter
Convert DNG to ORF in your browser. You download a Linear DNG (.dng), not a .orf: only an Olympus camera can create a genuine ORF, and every editor that opens ORF also opens DNG. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
RAW expected · other image formats also work
How to use DNG to ORF
- 1
Add your DNG files: drop them here, choose them, or paste from the clipboard.
- 2
There is nothing to tune: the DNG is written uncompressed. Resizing and rotating are under More options if you need them.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .dng files one at a time or together as a ZIP.
Why use Aback Images for dng to orf
Where a ORF would go
ORF files are opened by OM Workspace, Lightroom, Photoshop Camera Raw, Capture One and RawTherapee, and every one of them opens the DNG too.
The new DNG next to the original
The DNG stores the camera preview's pixels uncompressed, so it can be as large as the 15 to 40 MB raw file, or larger, depending on the preview's resolution.
No new artefacts
The preview inside the DNG is a camera JPEG; the DNG stores its decoded pixels uncompressed, so this step adds no compression damage of its own.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
DNG vs ORF
What changes from DNG to ORF
Encoding: the DNG uses lossless (or lossy) JPEG-compressed sensor data, plus optional JPEG previews; ORF uses losslessly compressed sensor data, with a preview and thumbnail, and the download is a Linear DNG: demosaiced 8-bit RGB with the colour matrices raw editors need.
Bit depth: 8 to 16 bits per channel in the DNG; ORF allows 12 bits per channel, and the DNG written here has 8 bits per channel, linearised. The raw data's 12 to 16 bits are not used: the embedded 8-bit preview is converted.
Colour: camera RGB plus the colour matrices that map it to XYZ (demosaiced linear RGB in a Linear DNG) in the DNG; ORF supports camera RGB from a Bayer mosaic, written here as 8-bit sRGB.
Metadata: the DNG can carry EXIF, XMP and DNG tags for colour matrices, calibration and lens corrections; ORF can carry EXIF and Olympus maker notes, which also contain the preview, but nothing is copied across.
About DNG
DNG is Adobe's openly documented raw format. Some cameras and phones record it directly, Adobe DNG Converter turns other brands' raw files into it, and a Linear DNG holds already-demosaiced RGB that raw editors treat like any other raw file.
DNG is built on TIFF/EP. The raw image sits in a sub-IFD marked as the main image, with tags for black and white levels, colour matrices and the colour filter pattern; a Linear DNG (PhotometricInterpretation 34892) stores demosaiced RGB instead of a mosaic. Previews are optional, and Adobe DNG Converter can write a medium (1024 px), full-size or no preview.
DNG files usually come from Leica, Pentax and Ricoh cameras, DJI drones, Google Pixel and iPhone ProRAW, and Adobe DNG Converter.
About ORF
ORF is the raw format of Olympus and OM System cameras, built around Four Thirds and Micro Four Thirds sensors. It stores 12-bit sensor data with a JPEG preview kept inside Olympus's maker notes.
ORF looks like TIFF but replaces the version number 42 with the letters 'RO', so a little-endian file starts 'IIRO' and generic TIFF readers reject it. Its JPEG preview is not in the main image directory but inside the camera-settings block of Olympus's maker notes.
ORF files come from Olympus E-series DSLRs, OM-D and PEN mirrorless cameras and OM System bodies.
When converting DNG to ORF makes sense
Forms and workflows that ask for ORF usually feed a raw editor, and each of those opens DNG as well, so the DNG can take the ORF's place. Keep the DNG if you only need to view or share the picture.
What ORF offers when it comes straight from the camera: Compact files from a smaller Four Thirds sensor; High Res Shot results stored as a single file; Supported across two decades of Olympus and OM System bodies. Its drawbacks: An 'IIRO' header that generic TIFF readers reject; 12-bit depth, less than most full-frame raw files; A preview hidden inside the maker notes.
Limitations
- A DNG from Adobe DNG Converter may carry only a medium 1024 px preview, and the largest preview in the file is what gets converted.
- Phone DNGs such as Apple ProRAW and Pixel raw are already computationally processed; the preview shows that processed result.
- A Linear DNG without a preview, such as one written by this site, is read from its RGB data instead.
- The DNG holds the decoded 8-bit pixels, so it adds no dynamic range or detail beyond the DNG.
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Frequently asked questions
Why do I get a .dng file instead of a .orf?
A real ORF is written by Olympus cameras and holds the sensor's own readings (12 bits per channel, stored as losslessly compressed sensor data, with a preview and thumbnail) along with EXIF and Olympus maker notes, which also contain the preview. This converter reads the JPEG preview inside the DNG, not its sensor data, so it cannot make one either. The Linear DNG you get instead is Adobe's open raw format, and every editor that opens ORF files opens it with the same raw controls. It holds decoded pixels, so it adds no quality or dynamic range.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.