Noise reduction vs resolution tradeoff?

Discussion in 'Digital Darkroom' started by rconey, Jul 24, 2021.

  1. Without getting too technical (It's a long time since my college physics) what is the tradeoff in resolution as we apply increasing color noise reduction in an image. If it's as simple as "increasing noise reduction reduces resolution linearly", then say so. Thanks.
     
  2. This tradeoff must vary depending on the algorithm used, but I doubt anyone other than the vendor could tell you an approximate mathematical relationship
     
    digitaldog likes this.
  3. colour NR shouldn't affect resolution say VS luminance NR.
     
    dcstep likes this.
  4. Hmm, thanks. I've found that Adobe ACR now sets a default color noise reduction of 25, far higher than most images need when shot at base iso. I sometimes forget to reset it, and am trying to decide how much I care about that.
     
  5. I think you might find that 25 is actually zero noise reduction and 0 adds noise. It allows for ACR to match different RAW outputs. Just guessing.
     
    Last edited: Jul 26, 2021
  6. digitaldog

    digitaldog Andrew Rodney

  7. As above. When I think about it, I blow the image up to 100% over a dark area, turn the slider sown to zero, and then put back whatever noise reduction is needed. At base iso that is commonly zero, and usually less than 15. I am guessing that less manipulation of the data is better.
     
  8. The salient part of the message is

    " A default setting of 25% is applied to all raw or raw DNG images, but if you open a TIFF, or JPEG image, Camera Raw assumes the image has already been pre-sharpened and applies a 0% Amount setting"

    Something good to know which could have been just referred to in a less snarky way. But it fits a pattern.
     
  9. digitaldog

    digitaldog Andrew Rodney

    I apologize that providing the facts and correcting your guess/assumptions appear snarky.
     
  10. digitaldog

    digitaldog Andrew Rodney

    You can set raw defaults for this specific to your ISO of the capture:

    https://helpx.adobe.com/camera-raw/kb/acr-raw-defaults.html
     
  11. OP...don't know what it all means. With me, the only 'means' that is important is the final print or image. If it is doable or hopefully pretty good that is all that counts. If it is too crappy, then that is the answer. The answer is not in the books or wiki.
     
  12. Dog...., thanks for the link. I will dig in when I have time. I have been in that dialog box before and could not work out how to save my preferences. In the past there was a simple check box in a pulldown of an ACR panel to "Save Preferences" or something to that effect. A few versions back it got more complicated, which is when this question arose.
     
  13. For the record, I went in thru the listed link above and went around in circles again..... BUT I found the way to set my defaults again. In the latest ACR at the bottom of the tool options (top right) is "...". Click that after setting the default settings you want. Then click "Save Settings". That will take you to a file for saved settings- name it what you like.
    THEN go into the "Set Raw Defaults" out of the same "..." menu. That dialog box then lets you set the camera and the default setting. This time you will choose "Choose Preset" then "User Preset" out of drop down boxes (same "..." choice on the far right). Choose the one you just saved and you are good. For now. I think.
     
  14. I'm way late to this thread, but I thought that it might be useful to some if I describe how I use DxO's DeepPRIME noise reduction when dealing with feathers and fur detail. Lately, I'm shooting with the Sony a1 and shoot at it's 2d native ISO of ISO 500, whenever possible. So long as I don't underexpose, images at ISO 500 require no NR. When shooting at ISO 1000 and higher I'll apply DxO's excellent DeepPRIME NR. I'll leave chrominance at 100%, but reduce luminance from the default of 40 to 20, so as not to smear fur and feather detail. I'll also raise Fine Contrast to around 20 to sharpen detail.

    Here's a shot taken with the a9 at ISO 25800, process with DeepPRIME at the settings discussed in the previous paragraph. Sorry for the size, but I wanted you to be able to pixel-peep:

    [​IMG]Handsome Tests The Air by David Stephens, on Flickr
     
  15. Back to Hepburn (Katherine) again--


     
  16. Thanks all. I agree that the final output is what matters. Good is good, and ugly is ugly. I do have some interest in what is happening under the hood, though.
     

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