CR3 File (.cr3): What It Is and How to Open It

The basics

What is a CR3 file?

CR3 is Canon's third raw photo format. It arrived in 2018 with the EOS M50, the first camera with Canon's DIGIC 8 processor, and Canon's new EOS cameras have used it since, including the EOS R mirrorless system. It replaced CR2, which was based on TIFF.

Two things changed. The container is now the ISO base media file format, the structure behind MP4 and HEIF, instead of TIFF. And the raw data uses a new codec, CRX, which also made a smaller, lossy option possible: C-RAW. Canon uses the same container and codec for its Cinema RAW Light video files (CRM).

Like any raw file, a CR3 holds the sensor's data before the camera has set the white balance, picture style, contrast and sharpening. It's meant for editing; to share a photo, export a JPG.

Anatomy

What's inside a CR3 file

A CR3 file is made of boxes, the same structure as MP4, MOV and HEIC files: each box has a 4-byte size and a 4-letter type, and some contain other boxes. Canon hasn't published the format. This outline follows Laurent Clévy's reverse-engineered description (the canon_cr3 project), ExifTool's Canon tag documentation and PRONOM's signature; box order and track contents can vary between cameras. No real file is shown, and only the signature bytes are given.

photo.cr3 (box outline)

photo.cr3: box layout of a Canon RAW 3 file (no real file shown)

box                                  contents
ftyp                                 file type, brand "crx "
  bytes 4–11: 66 74 79 70 63 72 78 20   "ftypcrx "
moov                                 the index of everything below
  uuid 85C0B687-820F-11E0-             Canon's metadata box
       8111-F4CE462B6A48
    CNCV                               codec version: "CanonCR3…"
    CCTP, CCDT                         the list of tracks
    CTBO                               offsets of XMP, preview and mdat
    CMT1                               TIFF IFD 0: make, model, date
    CMT2                               Exif IFD: exposure settings
    CMT3                               Canon maker notes
    CMT4                               GPS IFD
    THMB                               160 × 120 JPEG thumbnail
  trak 1                             full-size JPEG
  trak 2                             small raw image (CRX)
  trak 3                             full-size raw image (CRX):
                                       lossless RAW or lossy C-RAW
  trak 4                             Canon timed metadata (CTMD)
  (trak 5)                           dual-pixel data, in some files
uuid BE7ACFCB-…                      XMP metadata
uuid EAF42B5E-…                      PRVW: a medium-size preview JPEG
mdat                                 the data the tracks point to: JPEG,
                                     raw images and metadata records

1ftyp, 66 74 79 70 63 72 78 20
File type box
The first box declares the brand crx , Canon's raw brand. Canon's Cinema RAW Light video files (CRM) use the same brand; software tells them apart by the codec version string.
2uuid 85C0B687-…
Canon's metadata box
ISO base media files allow private boxes identified by a 16-byte UUID. Canon puts its metadata in one inside moov, with sub-boxes of its own.
3CNCV
Codec version
A text string beginning CanonCR3, followed by version numbers. CRM video files have CanonCRM here, which is how ExifTool decides which of the two a file is.
4CMT1 … CMT4
TIFF inside an MP4
The familiar photo metadata is stored as four small TIFF structures: the main IFD (camera make, model, date), the Exif IFD (shutter speed, aperture, ISO), Canon's maker notes, and GPS. So Exif tools can reuse their TIFF code, once they find these boxes.
5THMB, PRVW, trak 1
Three previews
A 160 × 120 thumbnail, a medium-size preview JPEG in its own box, and a full-size JPEG in the first track. Camera screens, file browsers and photo-culling tools use these without touching the raw data.
6trak 2, trak 3
The raw images
Usually a small raw image and the full-size one, both encoded with Canon's CRX codec. Each track's sample table points to where its data lies in mdat, as it would for frames of video.
7trak 4 (CTMD)
Timed metadata
Canon timed metadata records, the same mechanism its video files use. In a still photo they hold extra shooting data.
8mdat
The data
All the bytes the tracks point to, usually most of the file. A CR3 is laid out more like a one-frame video than like a TIFF photo.

Variants

RAW vs C-RAW: lossless and compact raw

CR3 cameras let you choose between two kinds of raw file. Both have the .cr3 extension and full resolution:

	RAW	C-RAW
Compression	Lossless	Lossy (wavelet-based)
Size	Large	DPReview measured the EOS M50's C-RAW files at 30–40% smaller than lossless CR2
Quality	Every recorded value kept	Hard to tell apart in normal edits; differences can show when deep shadows are brightened a lot
Good for	Difficult light, heavy editing, archives	Bursts, travel, filling cards more slowly

Reverse-engineering work describes CRX coding as similar to JPEG-LS (adaptive Golomb-Rice coding with edge prediction), with C-RAW adding a three-level wavelet transform, the kind of method JPEG 2000 uses. Some cameras can also record Dual Pixel RAW, which adds data from the two halves of each autofocus pixel for adjustments after shooting, in an extra track.

Why it looks flat

A CR3 opened in most raw editors looks flatter and less colourful than the camera's JPEG, because the camera's picture style isn't applied. Canon's Digital Photo Professional reproduces the camera's styles; other editors offer profiles that imitate them.

Compatibility

Why older software can't open CR3 files

When CR3 appeared, a lot of software that read CR2 couldn't open it, and some older tools still can't. The reasons:

A different container. Code that knew how to walk a TIFF-based CR2 found an MP4-like file instead, and needed a new parser.
A new, undocumented codec. Canon didn't publish CRX. Open-source decoders exist because developers worked it out from sample files; the source code of one such decoder, written by Alexey Danilchenko, was released in October 2019. Libraries such as LibRaw added CR3 support after that, and apps built on them followed.
Every new camera needs support. Even with CR3 itself supported, a raw converter needs colour calibration and sensor details for each model. A file from a camera newer than your software may still fail.

Fixes, in order: update the app (Lightroom, Photoshop's Camera Raw, Capture One, darktable, RawTherapee); use Canon's free Digital Photo Professional, which Canon updates for its new cameras; or convert the CR3 files to DNG with the free Adobe DNG Converter, whose output older DNG-capable software can open. Set its compatibility option to an older Camera Raw version if the DNGs still won't open.

How to

How to open, edit and convert a CR3 file

Windows: install Microsoft's free Raw Image Extension from the Microsoft Store (it's built on LibRaw and supports CR3). File Explorer then shows thumbnails and Photos opens the files.
Mac, iPhone and iPad: Photos and Preview open CR3 files from the Canon cameras on Apple's supported RAW list, which includes the EOS M50, EOS R5 and EOS R6. Apple adds new models in system updates.
Edit: Canon Digital Photo Professional (free for Canon owners), Lightroom, Photoshop, Capture One, DxO PhotoLab, and the free darktable and RawTherapee.
Convert to JPEG: develop in any of those and export.

terminal

# CR3 to JPEG with darktable or RawTherapee
darktable-cli IMG_0001.CR3 IMG_0001.jpg
rawtherapee-cli -o IMG_0001.jpg -c IMG_0001.CR3

# see the camera, lens, settings and whether it's C-RAW
exiftool -a -G1 IMG_0001.CR3

Many Canon cameras can also develop a raw file in the camera itself (RAW image processing in the playback menu) and save a JPEG next to it, which is handy when you don't have a computer.

Comparison

CR3 vs CR2, DNG, JPEG and HEIF

	CR3	CR2	DNG	JPG / HEIC
Container	ISO base media (like MP4)	TIFF-based	TIFF-based	JPEG / HEIF
Data	Raw sensor values	Raw sensor values	Raw sensor values	A finished picture
Lossy option	C-RAW	No (M-RAW, S-RAW reduce resolution)	Lossy JPEG, JPEG XL	Always lossy
Specification	Unpublished	Unpublished	Public, ISO 12234-4	Public
Opens in	Raw software with CR3 support	Almost all raw software	Any DNG reader	Everything

Some recent Canon cameras can save HEIF instead of JPEG for HDR photos, but that's a finished 10-bit image, not raw data.

Privacy

Privacy: what a CR3 file records

GPS location, in the CMT4 box, when the camera has GPS or takes the location from a paired phone through Canon's app.
Serial numbers of the camera body and often the lens, in the maker notes.
Owner, artist and copyright text, if set in the camera.
XMP metadata added later by editing software: ratings, keywords, sometimes edit settings.

Share an exported JPEG with metadata removed rather than the CR3. exiftool -gps:all= IMG_0001.CR3 removes the location from a CR3 if you need to send the raw file; ExifTool can write CR3 metadata.

Sample files

There are no sample CR3 files on this page. Raw files come straight from the camera, so the simplest test file is one shot in RAW or C-RAW on a Canon EOS R or EOS M camera.

Put it online

Have a CR3 file? Give it a link.

Drop a CR3 on 99helpers and it gets its own web address, so you can send a raw photo to an editor or client as a link. Browsers can't display raw files, so the file downloads when the link is opened; add a JPG if people just need to see it.

Put a CR3 file online

Questions

CR3 files, frequently asked

What is a CR3 file?

A raw photo from a Canon camera made since 2018, such as the EOS R and M series. It holds the unprocessed sensor data plus JPEG previews, in a container built like an MP4 file.

How do I open a CR3 file on Windows?

Install Microsoft's free Raw Image Extension from the Microsoft Store, then open it in Photos. For editing, use Canon's Digital Photo Professional, Lightroom, darktable or RawTherapee.

Why can't Photoshop or Lightroom open my CR3 files?

Your version is older than the camera. Update Camera Raw or Lightroom, or convert the files with the free Adobe DNG Converter and open the DNGs.

What is C-RAW?

Canon's compact raw option in CR3 cameras: full resolution, lossy compression, noticeably smaller files. Differences from lossless RAW usually only show when shadows are pushed hard.

How do I convert CR3 to JPG?

Open it in a raw editor (Digital Photo Professional, Lightroom, Photos on a Mac, darktable) and export as JPEG, or use the camera's own RAW processing menu.

Is CR3 better than CR2?

It's newer rather than better for image quality: lossless CR3 holds the same kind of data. It adds C-RAW for smaller files, but older software can't read it.

Why does my file browser think a CR3 is a video?

CR3 uses the same box structure as MP4 and MOV. Tools that look only at the structure may label it as a video file; the crx brand in the first box marks it as Canon raw.

Related formats

Other file types explained

CR2 file DNG file CRM file HEIF file MP4 file RAW file JPEG file All file types

Keep going

Host a CR3 file

Put a Canon raw photo online at its own address.

Share a CR3 file

Send raw files as a link instead of an attachment.

Hosting guides

How to put files, reports and sites online.

Sources

Last reviewed 27 October 2026.