Occasionally I come across claims in camera reviews to the effect that some manufacturer bakes in noise reduction into raw files, and does not allow turning it off.
But whenever I research these claims I find that they are incorrect; or the manufacturer fixed it with a firmware update (eg Pentax did this in the GRII).
Are there any cameras which have mandatory noise reduction in raw files, which cannot be turned off?
(Some/most?) Canons are for example known to bake in noise reduction. You can use photonstophotos.net to check any camera you’re interested in (don’t know exactly how Bill determines it though…). However it doesn’t say, and I don’t know, for which you can turn it off…
I’m pretty sure Sony does that (the infamous “star eater” incident) and newer Pentax cameras do that, too. I heard and am under the impression that most new cameras do that in general, though I haven’t been bothered to check if that’s true or not.
That was about lossy compression IIRC?
I did a quick search before posting and seems like it’s a hot pixel reduction issue (Sony Star Eater)? I don’t use Sony so I just hear other people talking about it’s a in camera NR issue but don’t know the detail, so maybe I’m wrong about this, but I’m sure newer Pentax/Ricoh GRs has mandatory NR applied to raw files.
Neither do I, so could still very well be. Looks like lossy compression is responsible at least for some other artifacts. Sorry for the digression!
No, it looks like a specific noise reduction algorithm (aimed at removing hot pixels).
Apparently via 2D Fourier Transform, very clever.
I use Sony, and have no complaints about not being given in any noise in the raw files, :lol: . There are plenty of instances where their secret-sauce de-noising is giving clean jpegs, but the raw needs denoising (in the pics I take) for skin/shadow areas.
But I have no way to be sure that they are not removing anything. My hunch is they are not. But I’m also aware of the astro star-binning problem.
Canon uses hot pixel removal at high ISO. For 6D and M5 ISO 6400 and above. For R6 ISO 12800 and above.
https://kameratrollet.se/wp-content/uploads/2022/11/hot-pixels-ISO6400vsISO3200.zip
No one complains about missing noise, it is about missing detail. There is concern about how demosaicing and denoising stages interact with these kind of manipulations (star eater is just an extreme example, but one can get fringes, etc) because the their underlying assumptions (mainly, IID noise) are not valid.
It defeats the purpose of raws if cameras denoise images, or do any other processing, before saving the raws.
As far as I know, no algorithm can guarantee to remove noise without also removing detail. Of course, it may decide things like, “This patch seems to be cloudless sky which has no detail, so it can be entirely smoothed”. And this might prettify the image, or it might not. I would rather that was my decision.
In my view, noise rarely detracts from an image. But denoising can. I especially hate the way it can turn human skin into doll-like plastic.