CR2

What is a CR2 file?

Canon sensor data from older DSLR bodies. Holds far more tonal range than a JPG.

What CR2 is

CR2 is a container: a wrapper that holds streams encoded by something else. It stores a grid of pixels, so enlarging it past its own resolution softens it. It is used for photography and editing.

The extension is .cr2, and the full name is Canon Raw 2. Both matter less than what the file can hold, which is what the rest of this page is about.

Where CR2 came from

Canon published it in 2004. It comes out of Canon EOS digital SLRs bodies.

Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.

The specification belongs to its vendor

Reading it outside the vendor’s own software depends on work done by other people, usually by inspection rather than by documentation. That mostly works and occasionally does not, which is the reason to convert anything you intend to keep.

It is a legacy format

It still opens everywhere and is still written by older tools, but nothing new is being built around it. Convert what you mean to keep, and do not choose it for something starting today.

Nothing is thrown away

CR2 stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.

It cannot be transparent

CR2 has nowhere to record transparency. Anything transparent in the source is filled with a solid colour on the way in — white, unless something chooses otherwise.

Colour it can describe

Up to 14 bits per channel. It can work in RGB.

More than eight bits per channel is what stops a gradient from stepping when it is edited, which is why it matters in a working file and rarely in a finished one.

What opens CR2

Adobe Lightroom, Canon Digital Photo Professional and darktable read it, and so do most programs of the same kind.

If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.

Opening it in a browser

No browser reads it.

That is the single most common reason to convert it: not that the format is bad, but that the place you want to show the file cannot read it.

What it can carry besides the content

CR2 can hold EXIF, XMP and GPS coordinates.

The GPS coordinates are the field worth thinking about before sending a file anywhere: they say where the photograph was taken, and almost nothing warns you that they are still in there.

It is a working format

CR2 is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.

What goes wrong with it

The recurring complaints: programs often show an embedded preview rather than the real data and support outside its home ground is uneven.

None of these is a reason to avoid the format. They are the things worth knowing before you are surprised by one, which is a different claim and a more useful one.

The facts, in one place

Identifiers and provenance for the CR2 format.
Extension.cr2
Media typeimage/x-canon-cr2
Published byCanon
First published2004

Converting CR2 to something else

Formats worth considering instead of CR2