A camera raw file holds what the image sensor recorded, before the camera turned it into a finished photo. There is no single RAW format. Every manufacturer has its own, and the extension tells you which one you have. Files that literally end in .raw mostly come from Panasonic Lumix cameras made before 2008 and their Leica twins, a few come from the Contax N Digital, and some are not photos at all but bare pixel dumps from scientific or graphics software. This page covers camera raw in general. The brand pages go into the details.
Which raw format do you have
| Extension | Manufacturer | Cameras |
|---|---|---|
| ARW | Sony | Alpha mirrorless and SLR/SLT cameras, RX compacts, since 2006 |
| SRF | Sony | DSC-F828 and DSC-V3 (2003–2004), Sony's first raw format |
| CR2 | Canon | EOS cameras from 2004 until CR3 took over in 2018 |
| NEF | Nikon | all Nikon cameras with raw |
| ORF | Olympus, OM System | E-system, PEN, OM-D, OM System, Tough |
| PEF | Pentax | Pentax DSLRs (most can also save DNG) |
| RW2 | Panasonic | Lumix since 2008 |
| RAW | Panasonic, Leica | older Lumix compacts such as the FZ50 or LX2, Leica Digilux 2, D-LUX 3 |
Adobe's DNG is the open alternative. Leica, Pentax, Ricoh and many smartphones (Apple ProRAW, Android raw capture) write it directly.
What is inside a raw file
Most sensors sit behind a colour filter array, usually the Bayer pattern: each photosite sees only red, green or blue. A raw file stores those single-colour values and the software later works out the two missing colours for every pixel. This step is called demosaicing, and it is the main reason two raw converters produce slightly different pictures from the same file.
- Bit depth. Raw data has 12 or 14 bits per photosite, which is 4,096 or 16,384 levels, against 256 per channel in an 8-bit JPEG. That headroom is what lets you pull back blown highlights or lift shadows.
- Settings are only notes. White balance, picture style, sharpening, noise reduction and lens corrections are recorded as metadata. You can change them later without any loss.
- TIFF underneath. Almost all vendor formats follow the structure of TIFF/EP (ISO 12234-2): directories of tags, EXIF, maker notes and one or more embedded JPEG previews. Quick thumbnails, and some viewers that show only a small image, use those previews.
- Compression. Depending on the brand and setting it is none, lossless, or lossy (Sony's compressed raw, Nikon's lossy NEF option). A 24 MP raw file typically takes 20 to 50 MB.
How to open raw files
- Windows 10 and 11: Photos and File Explorer show raw files once you install the free Raw Image Extension.
- macOS, iPhone, iPad: Preview and Photos read raw files from the cameras on Apple's support list.
- Free editors for all systems: darktable and RawTherapee (Windows, macOS, Linux). GIMP opens raw files through either of them.
- Manufacturer software: Canon Digital Photo Professional, Nikon NX Studio, Sony Imaging Edge Desktop and OM Workspace are free for owners of the brand's cameras.
- Adobe: Lightroom and Photoshop through Camera Raw. The free Adobe DNG Converter turns raw files into DNG for older software.
Common problems
Raw file won't open, "camera not supported"
Raw formats change with every camera generation. A program released before your camera does not know its files, even if the extension is familiar. Update the program or its raw component, or check the list of supported cameras on the program's website.
The raw photo looks flat or darker than on the camera
The camera display shows a JPEG made with your picture style, contrast curve and lens corrections. A raw developer starts from its own neutral defaults. Nothing is damaged, the look simply has not been applied yet.
A .raw file that is not from a camera
Photoshop's "Photoshop Raw" option, scanners and lab cameras write bare pixel data without any header. Such a file cannot be read unless you know its width, height and bit depth. ImageJ (File → Import → Raw) or Photoshop will ask for them. Our converter cannot guess them.
Converting raw to JPG, PNG or TIFF
People convert raw files to share them, print them or upload them somewhere that only takes JPG. Our converter develops the raw data using the white balance set in the camera, automatic brightness and the sRGB colour space, and turns the picture upright according to its orientation tag. It then saves JPG at quality 90, PNG or TIFF, all with 8 bits per channel.
What you give up: the 12 or 14-bit headroom and the freedom to change white balance later. The camera's picture style and its lens corrections for distortion and vignetting are not applied, and EXIF data is not carried over in full. If you plan to edit, develop the file yourself in darktable or RawTherapee and export a 16-bit TIFF. In any case keep the original raw file, or a DNG copy, as your negative. Canon and Nikon users will find details on the CR2 to JPG and NEF to JPG pages.
Camera raw at a glance
| Type | unprocessed sensor data with metadata and preview |
|---|---|
| Developers | each camera manufacturer separately |
| Common basis | TIFF/EP, ISO 12234-2 (2001) |
| Open alternative | DNG (Adobe, 2004) |
| Bit depth | usually 12 or 14 bits per photosite |
| Compression | none, lossless or lossy, by brand and setting |
| Typical use | photography where the picture will be edited afterwards |
Background reading: the Library of Congress descriptions of camera raw formats and of DNG.