What is the RAW file format?
.raw (Raw Image Data) is one of the most popular file formats for minimally processed images captured by digital cameras. A .raw file stores image data recorded by the camera's sensor directly, with little or no in-camera processing applied.
RAW graphics files are widely considered the best format to store photographic images, because the format preserves raw sensor data with no lossy compression and no destructive in-camera processing, resulting in high-fidelity files. Users can adjust the image for exposure, white balance, and many other aspects non-destructively using professional editing software.
.raw files are characterized by a wide tonal spectrum, absence of lossy compression (some variants use lossless compression internally), and 12- or 14-bit per channel depth - compared to JPEG's 8 bits per channel. This additional bit depth gives editors significantly more latitude to recover highlights and shadows. .raw files are sometimes described as the digital counterpart of a film negative.
Because .raw files store unprocessed sensor data, they can be quite large. They tend to be significantly larger than JPEG files and roughly comparable in size to TIFF files, though losslessly compressed variants can be noticeably smaller.
Almost all digital camera manufacturers use their own proprietary RAW formats rather than the generic .raw extension. Canon uses .CR2 and the newer .CR3, Nikon uses .NEF, Olympus uses .ORF, Sony uses .ARW, and Fujifilm uses .RAF. The literal .raw extension is used by a smaller group of manufacturers including Panasonic (older models), Leica, Contax, Casio, and Phase One medium-format camera backs.
Security & safety
RISK: LOWA camera .raw is passive image data - sensor values and metadata, no executable code - so opening one is safe. Cautions are non-malware: raws are large and often proprietary, so back up originals and consider DNG for longevity; and EXIF/maker metadata (camera, sometimes GPS, timestamps) travels with the file - strip it before publishing if privacy matters. Separately, be aware a .raw might NOT be a photo at all (raw audio, raw disk image); don't force a photo app on a mismatched file.
Format details
in a nutshell- Raw audio (headerless PCM) - A .raw file can be uncontainerized PCM audio - raw sample values with no header (sample rate/bit depth must be supplied manually); open in Audacity via Import → Raw Data.
- Raw disk / memory image - Forensics and virtualization tools produce .raw (a.k.a. .dd/.img) bit-for-bit disk or RAM dumps - not an image you can view in a photo app.
- Raw binary / 3D voxel data - Scientific and 3D tools export plain .raw arrays of bytes (e.g. volumetric voxel grids); meaning depends entirely on the producing application.
Programs that open RAW files
Windows5 apps
darktable
Open-source Free Lightroom-style raw developer; import the .raw, edit exposure/white balance non-destructively, export JPG/TIFF. 
RawTherapee
Open-source Free, powerful raw processor; open the .raw and develop/export. Strong demosaicing for many cameras. 
Raw Image Extension (Microsoft Store)
Free Install from the Microsoft Store so File Explorer and Photos can show raw thumbnails/previews (covers many camera raw types).
Adobe Lightroom / Photoshop (Camera Raw)
Paid Import the raw; Camera Raw develops it. Industry standard, subscription-based.
IrfanView (+ RAW plugin)
Free Fast viewer; with its RAW plugin it displays many .raw files and batch-converts to JPG. 
macOS3 apps
Apple Photos / Preview
Built-in macOS has broad built-in raw support - double-click to preview, or import into Photos to view/edit. 
Linux3 apps
GIMP (+ darktable/RawTherapee plugin)
Open-source GIMP opens raw via its darktable/RawTherapee loader, then edits as a normal image. Technical details
deep spec| MIME type | image/x-raw |
| Format type | Binary, vendor-specific; no single universal layout across all .raw files |
| Magic bytes | No universal file signature; TIFF-based variants use standard TIFF byte-order markers (II or MM) |
| Bit depth | 12 or 14 bits per channel (sensor raw data); some medium-format variants store 16 bits |
| Color filter array | Bayer RGGB mosaic (most cameras); X-Trans mosaic in some Fujifilm-based .raw variants |
| Demosaicing | Required - pixel data is stored pre-demosaic; software must interpolate full-color pixels from the CFA grid |
| Compression | Ranges from none (bare pixel dump) to lossless, depending on the variant |
| White balance | Stored as multiplier coefficients in file metadata; applied non-destructively in post-processing |
| Color space | Sensor-native linear light; no ICC profile embedded in the raw pixel data itself |
| Known .raw extension users | Panasonic (older models), Leica, Contax, Casio, Phase One medium-format backs, certain Nikon film scanners |
| Embedded metadata | EXIF and MakerNote blocks present in TIFF-based variants |
| Processing library | LibRaw (actively maintained) and the legacy dcraw utility parse most .raw variants |
| Typical file size | 10-30 MB per frame, varying with sensor resolution and compression method |
| Dynamic range | Typically 12-14 stops of captured tonal latitude, sensor-dependent |
| Released | 1990s-2000s (used literally as .raw by several camera/scanner makers) |
| Specification | www.libraw.org |
RAW conversions
Community Q&A
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