Will updating a C-RAW (.CR3) file cause data loss?

[krahe]

I have an M50 Mark II and for important shots I record in both JPG and C-RAW (compressed raw - .CR3) format. I can use Digital Photo Professional 4 to make adjustments to these photos such as to adjust the brightness. What I want to know, though, is whether making such changes and then updating the .CR3 file causes a loss of information. For instance, if I open a .CR3 and then adjust the Brightness by -1.33 and re-save the file, then come back later and re-open the .CR3 and change the Brightness adjustment back to 0, will I end up with the same image I started with before making any adjustments? Or to put it another way, if I later decide I want to make additional adjustments, perhaps to other attributes like color or to reduce noise, would I want to start with a copy of the original file the way it existed before I adjusted the brightness, or is it "okay" to simply apply additional changes to the same file? (Or if there might be a difference, would it be so tiny that a relative amateur like me would likely never discern it?) Thank you!

[jrhoffman75 · Accepted solution]

Welcome to the forum. 

DPP4 is a non-destructive editor. Any adjustments you make in DPP are saved in a recipe that are applied to an image when you Convert and save - the original file is never changed. 

If you edit a RAW file in DPP and later open that same file in another RAW editor like Lightroom you won’t see the DPP edits. Similarly, if you edit a RAW file in Lightroom and then later open that file in DPP you won’t see any of the Lr edits in DPP.

[krahe]

Excellent. So the pixel-level data remains an original recording of the shot. That's what I was hoping.

[johnrmoyer]

I am not saying that anyone else should do things as I do them, but in case it might be helpful this is what I do.

I usually save a recipe file from DPP and do not save the CR3 file. When I open the CR3 file in DPP in the future, I am back to the recipe the camera used at the time of the shot. Then I can load and apply a saved recipe if I want my edits or to do further editing. I think of the recipe file as a record of how i produced a JPEG or a TIFF version of the image and the CR3 file as a record of what the camera did. It would also work to save a recipe file before editing and save the CR3 file with the changes so that one might later retrieve the choices the camera had made.

If I crop an image in more than one way, I will save two recipe files. I might also save a separate recipe file if I am saving a 16bit tiff from DPP for editing in another program. I might save a separate recipe file for a black and white version of the image.

[krahe]

That's how a relative who shoots with a Nikon indicates his software works. I didn't realize I had that option with DPP, but now I see it in the Edit menu. There is also a tantalizing item in that menu, "Paste recipe of original image to edited image." However, it is disabled, and nothing I do seems to enable it. It would be interesting to know exactly what that function does and how to enable it, but I can't seem to find any information about it.

[johnrmoyer]

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@krahe wrote:

That's how a relative who shoots with a Nikon indicates his software works. I didn't realize I had that option with DPP, but now I see it in the Edit menu. There is also a tantalizing item in that menu, "Paste recipe of original image to edited image." However, it is disabled, and nothing I do seems to enable it. It would be interesting to know exactly what that function does and how to enable it, but I can't seem to find any information about it.

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I cannot find that option on DPP or in the manual. The only way I know to paste a recipe is if I have copied the recipe first. The section in the DPP manual on raw images has more about recipe files. Also,

https://cam.start.canon/en/S002/manual/html/UG-04_EditImage_0300.html