What is the CR2 file format?
A .cr2 file stores raw image data captured with a digital camera sensor developed by Canon. It is version 2 of the format. .cr2 is a proprietary format that stores data in binary and may apply lossless compression, though files are still quite large. Like a photo negative, a .cr2 must be 'developed' before use as a finished image - users can adjust parameters such as white balance or exposure during this step. Canon cameras that first used the .cr2 format include:
- 1D Mark II,
- 20D,
- 350D,
- G9.
A .cr2 file has a header that contains EXIF data - information about the picture, the camera, and image parameters. It also contains a compressed preview image roughly one-fourth the size of the base photo, plus a small 160×120 pixel thumbnail. .cr2 stores image data in 12-bit or 14-bit color depth; the detailed file structure varies depending on the specific camera model used.
.cr2 is based on TIFF and replaced the .CRW format in 2004. In 2018 Canon introduced .CR3, a newer format built on the ISO Base Media File Format (ISOBMFF) container - not TIFF - which has since become standard on newer Canon EOS R mirrorless and later DSLR models. Applications that support .cr2 files must also be compatible with the specific Canon camera the file was taken with. Once developed, the processed photo can be saved in a more widely supported format, such as JPEG, for easier distribution.
Security & safety
RISK: LOWCR2 is a passive image data file - it contains sensor data and metadata, not executable code, so opening one is safe. The practical cautions are non-malware: CR2 is large and proprietary, so keep originals backed up and consider archiving to open DNG for longevity; and remember EXIF/maker-note metadata (camera, sometimes GPS, timestamps) travels with the file - strip it before publishing if privacy matters. Editing is non-destructive in raw developers, so the original CR2 is preserved.
Format details
in a nutshellPrograms that open CR2 files
Windows6 apps
darktable
Open-source Free Lightroom-style raw developer; import the CR2 to edit non-destructively and export JPG/TIFF. 
RawTherapee
Open-source Free, powerful raw processor with excellent Canon demosaicing; open the CR2 and export. 
Raw Image Extension (Microsoft Store)
Free Install from the Microsoft Store to show CR2 thumbnails/previews in File Explorer and the Photos app.
Canon Digital Photo Professional (DPP)
Free Canon's own free raw editor (download from Canon support with your camera model); opens and develops CR2 natively.
Adobe Lightroom / Photoshop (Camera Raw)
Paid Import the CR2; Camera Raw develops it. Industry standard but subscription-based.
IrfanView (+ RAW plugin)
Free Fast free viewer; with its RAW plugin it displays CR2 and batch-converts to JPG. 
macOS3 apps
Apple Photos / Preview
Built-in macOS has built-in Canon raw support; double-click to preview, or import into Photos to view/edit CR2.
Canon Digital Photo Professional (DPP)
Free Canon's free raw editor for Mac; develop CR2 with model-accurate colour. 
Linux3 apps
GIMP (+ darktable/RawTherapee plugin)
Open-source GIMP opens CR2 via its darktable/RawTherapee raw loader, then edits as a normal image. Technical details
deep spec| Container base | TIFF (Tagged Image File Format) IFD structure |
| Magic bytes | `49 49 2A 00` (little-endian TIFF header) at offset 0; `43 52` (`CR`) at offset 8 |
| MIME type | `image/x-canon-cr2` |
| Bit depth | 12-bit or 14-bit per channel, depending on the camera model |
| Raw sensor pattern | Bayer RGGB mosaic - demosaicing is performed during processing, not in-camera |
| Main image compression | Lossless JPEG (ISO 10918-1 lossless) applied to the primary RAW strip |
| Embedded previews | Three JPEG previews: 160×120 px thumbnail, medium (~1/4 size), and full-resolution JPEG |
| IFD count | Four IFDs: IFD0 (thumbnail), IFD1 (small JPEG), IFD2 (full JPEG preview), IFD3 (RAW data) |
| EXIF metadata | Full EXIF 2.x block in IFD0, including shooting parameters, GPS (if available), and lens info |
| Canon MakerNote | Proprietary sub-IFD with AF data, lens identity, picture style, and in-camera processing flags |
| Endianness | Little-endian (Intel byte order - `II` marker in TIFF header) |
| Typical file size | 15-35 MB per image, depending on camera resolution and model |
| Camera generation covered | Canon DSLRs from EOS 1D Mark II / EOS 20D (2004) through EOS 5D Mark IV / 6D Mark II (~2018) |
| Successor format | `.cr3` (Canon RAW 3), ISO Base Media File Format (ISOBMFF) container, introduced with EOS R series (2018) |
| Released | 2004 (Canon EOS 20D); used through ~2018 (e.g. EOS 5D Mark IV) |
| Specification | www.canon.com |
CR2 conversions
Community Q&A
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