Not yet canon raw files CR3 recognised by Rawtherapee

I have used with satisfaction for a long time Rawtherapee for my Canon cameras with yhe old CR2 files. From June i’m using the new mirrorless RP but Rawtherapee don’t recognise CR3 raw files. Many new Canon cameras are now using CR3 raw files. I have oped that the new 5.7 version could solve this but nothing again.
No prevision?? Pls help


@Julianus write to Canon to openly release the specification of their CR3 format for the benefit of all open-source software.

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I have no the technical skills and knowledge to do such a request. My only question is why the staff of Rawtherapee cant’t do such a request to Canon

@Julianus In an open-source world full of volunteers, anyone can contribute their time and effort. It is not the developers duty to provide anything.

So, maybe people have contacted Canon, and maybe Canon didn’t reply. In any case, as long as there is no publicly available documentation, or somebody with enough time and skill to reverse-engineer the CR3-format, it will not be available in RawTherapee. Sorry.


I know it’s been mentioned before elsewhere but I’ll repeat it here. As a workaround, you can use Adobe DNG Converter to convert these images to DNG format which RawTherapee supports. The converter is quick and easy to use and works on Mac, Windows, and even Linux under wine.

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Though converting the CR3 files to DNG is a workaround, the better solution would be a decoder for CR3 files without that step.

So I encourage all users of CR3-Cameras to write to Canon support to open the decoding. One RT contributor already wrote 5 mails to Canon support today.
If you, being FOSS CR3 users, also do that, there will be some more pressure.


In general, such requests to technical support fall upon deaf ears. I’ve never seen any example of any of the major camera manufacturers directly engaging with any FOSS project, with the slight example of the Sony wireless remote SDK back around when the QX family of cameras launched.

A lot of progress has been made on reverse engineering much of the format (fortunately, Canon used an MPEG-4 container which made things much simpler), but Canon is using a proprietary undocumented compression algorithm for the actual data itself, and reverse engineering this is EXTREMELY difficult.

There are rumors the libraw team may have an internal implementation that may get published as open source sometime in the coming months. I don’t think the Magic Lantern team has made any significant progress here either. (See ML for an example of a team that Canon could cooperate with in order to make their cameras more desirable - but instead Canon often does all they can to keep ML from tinkering with their cameras instead.)

I think this is the case, at least as far as I was able to understand. Last time I asked, they said that it should be out by fall or something like that. So, people just need to be patient…

Look at CR3 and CRX codec seemed to be figured out.

Doesn’t look like it to me - a bunch of likely matches between a Canon patent and data organization, but none of the low-level details are identified - and for something like this, even the fine details are important.