JPG to ORF Converter
Convert JPG 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
JPG expected · other image formats also work
How to use JPG to ORF
- 1
Add your JPG 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 jpg 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.
DNG next to JPG
The DNG is written uncompressed, so expect it to be several times larger than the JPG, which stores lossy DCT coding in 8×8 pixel blocks, with colour usually stored at half resolution.
No new artefacts
JPG is already lossy, since it stores lossy DCT coding in 8×8 pixel blocks, with colour usually stored at half resolution; the DNG keeps the 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.
JPG vs ORF
What changes from JPG to ORF
Encoding: the JPG uses lossy DCT coding in 8×8 pixel blocks, with colour usually stored at half resolution; 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 bits per channel in the JPG; ORF allows 12 bits per channel, and the DNG written here has 8 bits per channel, linearised.
Colour: YCbCr shown as RGB, greyscale, or CMYK from print software in the JPG; ORF supports camera RGB from a Bayer mosaic, written here as 8-bit sRGB.
Metadata: the JPG can carry EXIF (camera, date, GPS), XMP, IPTC and an ICC profile in APP segments; ORF can carry EXIF and Olympus maker notes, which also contain the preview, but nothing is copied across.
About JPG
JPEG is the universal photo format. It compresses by discarding fine detail the eye is least sensitive to, which makes photos small but blurs sharp edges and text if pushed too far.
A JPEG starts with the bytes FF D8 and is a run of marker segments: APP1 carries EXIF and often a thumbnail, APP2 an ICC profile, DQT the quantization tables that decide the quality, and SOS the compressed scan, which ends at FF D9.
JPG files usually come from cameras, phones, scanners and almost every app that saves photos.
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 JPG 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 JPG 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
- JPEG artefacts already in the file, such as blocking near edges and smeared colour, are kept as pixels: a lossless target preserves them faithfully rather than removing them.
- The DNG holds the decoded 8-bit pixels, so it adds no dynamic range or detail beyond the JPG.
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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. A JPG holds no sensor data, so no software outside the camera can create a genuine ORF. 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.
Does converting JPG to ORF lose quality?
DNG is written uncompressed, so the pixels are stored exactly as decoded. Artefacts already in the JPG stay, but nothing new is lost.
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.