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The noise reduction they're referring to is dark frame subtraction used for thermal noise and defective hot pixel removal (the latter is what the ISS has to wor

The noise reduction they're referring to is dark frame subtraction used for thermal noise and defective hot pixel removal (the latter is what the ISS has to worry about.) Numerous cameras from other companies allow for forcing that on at any speed via menu options, not just slower shutter speeds. I had this feature available on an early 2010's Olympus. They called it "Noise Reduction" (not "noise filter", that's different) and it could be set to off, normal, or "on." On makes it behave like this "special" Nikon firmware, always performing the dark frame subtraction. "Normal" applies some logic based on shutter speed and ISO, and off turns it off completely. Manual dark-frame calibration was also available via the menus. I'm not sure why Nikon is tooting their horn so loudly about adding (only for people in the ISS) what's been available to earthbound users of other camera systems via a menu item for a decade?

hef19898 3y ago
I guess the difference is some better algorithms to identify cosmic ray issues and the like, as oppossed to simple noise reduction.
- wdfx 3y ago
  Exactly - if you think about the automatic dead/hot pixel removal, the camera is going to assume these errors are always in the same location on the image, and maintain a mapping of where they are. If instead in space these errors are caused by cosmic rays and can affect any part of the image randomly, and for a limited time only, then this requires a different algorithm, otherwise the camera will eventually be painting out the entire image as different areas get affected. That all said, I know nothing of the details of these camera firmwares, and they may be doing other things instead. But, I suspect it is not as simple as some comments in this thread suggest... because nothing ever is.
- KennyBlanken 3y ago
  "Noise reduction" is not dark frame subtraction. What they are very clearly describing is dark frame subtraction, as they repeatedly mention damage from cosmic rays. Things are not helped by this being a press release munged up by a writer. "Noise reduction" is where the camera's image processor applies smoothing over different channels as part of all the other processing it does, such as vignette correction, chromatic diffraction compensation, and remapping for lens distortion. Some but not all of this is bypassed when doing RAW images. RAW processors (especially from the camera manufacturer) typically apply similar corrections automatically, but you have varying degrees of control over this. They're usually better quality due to more computational capabilities, and faster software development cycle vs stuff baked into the camera's ASICs or firmware.
malfist 3y ago
Dark frame subtraction cannot remove cosmic rays. It removes things the camera sees in the dark at the time of dark frame capture. This is things like dead pixels, hot pixels and amp glow. If a cosmic ray was removed by a dark frame, two cosmic rays would have had to happen, one during dark frame and one during the actual capture. They'd have had to be the same intensity and hit the same pixels. This is probably never going to happen. As for who this is for? You and I may benefit too with less cosmic ray noise in our photos. We still see them, though we have a lot more information in our photos. You can see them too if you take dark frames yourself. Even if you put your camera in the freezer to avoid most other noises you'll see them
- davidmurdoch 3y ago
  What's the freezer thing about?
  - dekhn 3y ago
    there are several sources of pixel noise, some of which are temperature dependent. Making the sensor cold reduces the temperature-dependent pixel noise background.
    - davidmurdoch 3y ago
      So less sensor noise, but all your lenses are foggy now. Haha
      - malfist 3y ago
        Well, for dark frames the lense cap is on. The idea is that you're taking a totally black photo. Freezer, along with being cold is also a big metal box that will help deflect some rays
      - dekhn 3y ago
        It's not the lens, it's the sensor that's kept cold- in practice, people taking low-noise shots would use something like this: https://amscope.com/products/mt5800-ccd https://amscope.com/products/mt5800-ccd If you put it in a freezer, you can use desiccant or other strategies to avoid moisture-fogging. Or just wait til everything reaches equilibrium?

hef19898 3y ago

I guess the difference is some better algorithms to identify cosmic ray issues and the like, as oppossed to simple noise reduction.

wdfx 3y ago
Exactly - if you think about the automatic dead/hot pixel removal, the camera is going to assume these errors are always in the same location on the image, and maintain a mapping of where they are. If instead in space these errors are caused by cosmic rays and can affect any part of the image randomly, and for a limited time only, then this requires a different algorithm, otherwise the camera will eventually be painting out the entire image as different areas get affected. That all said, I know nothing of the details of these camera firmwares, and they may be doing other things instead. But, I suspect it is not as simple as some comments in this thread suggest... because nothing ever is.
KennyBlanken 3y ago
"Noise reduction" is not dark frame subtraction. What they are very clearly describing is dark frame subtraction, as they repeatedly mention damage from cosmic rays. Things are not helped by this being a press release munged up by a writer. "Noise reduction" is where the camera's image processor applies smoothing over different channels as part of all the other processing it does, such as vignette correction, chromatic diffraction compensation, and remapping for lens distortion. Some but not all of this is bypassed when doing RAW images. RAW processors (especially from the camera manufacturer) typically apply similar corrections automatically, but you have varying degrees of control over this. They're usually better quality due to more computational capabilities, and faster software development cycle vs stuff baked into the camera's ASICs or firmware.

malfist 3y ago

Dark frame subtraction cannot remove cosmic rays. It removes things the camera sees in the dark at the time of dark frame capture. This is things like dead pixels, hot pixels and amp glow. If a cosmic ray was removed by a dark frame, two cosmic rays would have had to happen, one during dark frame and one during the actual capture. They'd have had to be the same intensity and hit the same pixels. This is probably never going to happen. As for who this is for? You and I may benefit too with less cosmic ray noise in our photos. We still see them, though we have a lot more information in our photos. You can see them too if you take dark frames yourself. Even if you put your camera in the freezer to avoid most other noises you'll see them

davidmurdoch 3y ago
What's the freezer thing about?
- dekhn 3y ago
  there are several sources of pixel noise, some of which are temperature dependent. Making the sensor cold reduces the temperature-dependent pixel noise background.
  - davidmurdoch 3y ago
    So less sensor noise, but all your lenses are foggy now. Haha
    - malfist 3y ago
      Well, for dark frames the lense cap is on. The idea is that you're taking a totally black photo. Freezer, along with being cold is also a big metal box that will help deflect some rays
    - dekhn 3y ago
      It's not the lens, it's the sensor that's kept cold- in practice, people taking low-noise shots would use something like this: https://amscope.com/products/mt5800-ccd https://amscope.com/products/mt5800-ccd If you put it in a freezer, you can use desiccant or other strategies to avoid moisture-fogging. Or just wait til everything reaches equilibrium?