What is the ARW file format?
.arw files are photo files created by Sony digital cameras, primarily the Alpha series. These are raw files which contain unprocessed image data captured directly from the camera's sensor. The .arw format shares many similarities with Sony's earlier .sr2 and .srf raw formats - both of which .arw succeeded when Sony acquired Konica Minolta's camera division in 2006.
The .arw format is built on the TIFF container and the TIFF/EP specification. It stores raw sensor data sent directly from the camera's image sensor, before any in-camera processing is applied. Depending on camera model and settings, the raw data may be stored uncompressed or in losslessly compressed form. Such files retain all captured image detail, which can be adjusted before exporting to a common format using graphic editors such as Adobe Lightroom, Sony Imaging Edge Desktop, or RawTherapee.
.arw raw image files may vary between specific Sony cameras, even though they share the same extension. These differences arise from different image sensors and internal sub-format versions used across camera generations. Seemingly identical .arw files can therefore differ in internal structure, though this is not visible to the naked eye - it only becomes apparent after examining technical metadata or when a raw processor encounters an unsupported sub-format.
Security & safety
RISK: LOWARW is a passive image data file - sensor data and metadata, not executable code, so opening one is safe. The practical cautions are non-malware: ARW is large and proprietary, so keep originals backed up and consider archiving to open DNG for longevity; and remember EXIF/MakerNote metadata (camera, lens, timestamps, sometimes GPS) travels with the file - strip it before publishing if privacy matters. Editing in raw developers is non-destructive, so the original ARW is preserved. Beware fake "ARW viewer/converter" download sites bundling adware; use Sony Imaging Edge or the Microsoft Store Raw Image Extension instead.
Format details
in a nutshellPrograms that open ARW files
Windows6 apps
darktable
Open-source Free Lightroom-style raw developer; import the ARW to edit non-destructively and export JPG/TIFF. 
RawTherapee
Open-source Free, powerful raw processor with strong Sony support; open the ARW and export. 
Sony Imaging Edge Desktop
Free Sony's free official software (Viewer + Edit); open the ARW to develop it with model-accurate colour, then export JPG/TIFF.
Raw Image Extension (Microsoft Store)
Free Install from the Microsoft Store to show ARW thumbnails/previews in File Explorer and the Photos app.
Adobe Lightroom / Photoshop (Camera Raw)
Paid Import the ARW; Camera Raw develops it. Industry standard but subscription-based. 
macOS3 apps
Apple Photos / Preview
Built-in macOS has built-in Sony raw support; double-click to preview, or import into Photos to view/edit ARW. 
Linux3 apps
GIMP (+ darktable/RawTherapee plugin)
Open-source GIMP opens ARW via its darktable/RawTherapee raw loader, then edits as a normal image. Technical details
deep spec| Container format | TIFF/EP (ISO 12234-2), little-endian byte order |
| Magic bytes | `49 49 2A 00` at file offset 0 (little-endian TIFF signature) |
| MIME type | `image/x-sony-arw` |
| Raw bit depth | 12-bit or 14-bit per channel (varies by camera model and setting) |
| Color filter array | Bayer RGGB mosaic (sensor-native; demosaicing applied at raw conversion) |
| Compression | Uncompressed, lossless compressed raw, or lossy compressed raw (model-dependent) |
| Embedded preview | Full-resolution JPEG preview plus smaller thumbnail stored in TIFF IFD |
| Metadata | EXIF 2.x plus Sony-specific MakerNote IFD for camera settings and lens data |
| Sub-format versions | ARW 1.x (2005-2008) and ARW 2.x (2009+), differing in compression and MakerNote layout |
| White balance | Shot white balance and daylight reference coefficients stored in MakerNote tags |
| Lens correction data | Distortion, chromatic aberration, and vignetting tables embedded in select bodies |
| Predecessor formats | Supersedes Sony `.srf` and `.sr2`, both derived from Konica Minolta raw |
| DNG conversion | Convertible to `.dng` via Adobe DNG Converter for wider software compatibility |
| Released | 2005 (Sony Alpha line, succeeding Konica Minolta's SRF/SR2); still in use on current Sony bodies |
| Specification | www.sony.net |
ARW conversions
Community Q&A
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