How do I processing RAW images in the same way my camera processes JPEGs?

Started Aug 7, 2022 | Questions thread
NAwlins Contrarian Veteran Member • Posts: 9,231
Re: Only one possibility

This is interesting. I was under the impression that many of these processes would be deterministic, but you are saying that there is a degree of interpretation involved.

Yes indeed there is very a quite significant degree of interpretation involved. Maybe the most important is white balance. The camera cannot know what is due to the color of the subject itself, versus the color of the light hitting it. When set to auto white balance, it has to make an educated guess. Sometimes it guesses accurately, sometimes not. Sometimes the camera's guess is pleasing, but sometimes not. And take the raw file into different raw converters, set them to 'as shot', and see that they report different values for temperature and tint. And of course either in camera or in raw converter, you can choose / set your own values, whether set by eye or by photographing and sampling something like the white-balance tiles on a ColorChecker Passport (a regular ColorChecker does not have any truly neutral tiles).

And although the camera may know the precise spectral filtration characteristics of the red, green, and blue filters over some (a quarter, half, and a quarter, respectively) of the pixels, a third-party raw converter may not.

For example, I had thought that when I set lens correction to ON in the camera, that I am relying on the camera to distort (or undistort) the image. And that is true for the in-camera JPEG. But I have just found a switch in RAW Power, 'Apple Lens Correction', and it comes on by default when viewing a RAW file ... and I guess that is using a different process to do lens correction.

This is very much an 'it depends' point, with different cameras, lenses, and raw converters behaving differently.

The original issue appears to be about mapping the gamut of the RAW image to the wide gamut of my MacBook's screen. I am effectively using Apple's RAW processes, as that is what both the application RAW Power and Pixelmator Pro rely upon.

And unless the screen is hardware-calibrated-and-profiled, and you're using it in the ambient light conditions under which it was calibrated and profiled, and you're using fully color-managed software, you can't really know what you're getting. The Mac OS ecosystem seems to be ahead the Windows ecosystem in this regard, but AFAIK there have been reports of some of the newer Mac OS versions 'breaking' some color management.

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