PL3 Noise Reduction

I have been pleased with the noise reduction features offered by PL - in particular Prime seems very effective. I am trying to understand the controls and what is really going on.

The Noise Reduction Menu offers separate controls for Luminance, Chrominance, Low Frequency, Dead Pixels, and Maze. There are brief descriptions for these controls in the application “?” option, but only Luminance and Chrominance are discussed or even mentioned in the Manual. There is an option for each control to turn Auto off - but these only effects Luminance (goes to 100%) and Dead Pixels (goes to 0%).

I’m trying to understand what exactly “Auto” does in this situation. The controls are the same for Fast and Prime, so there is no difference there. “Auto” it seems should take into consideration the characteristics of the individual image - but Luminance Auto is always set to 40% for every image - which doesn’t make sense if it is actually analyze the individual image. Prime apparently does this when it analyzes the image, but I don’t know how.

Has DxO published any discussion of how these noise reduction processes work? The result (does it look better?) is the ultimate criterion, but I would like to know what is happening. I am shooting now with a Sony A7RM4 and it takes 48 seconds to process one RAW image with Prime noise reduction turned on - that on an iMac Pro. So I hesitate to use Prime all the time. When should it be used?


I deal with this (maze) in my tutorial.
Dead pixel. PL cancel anarchical pixels (ei, blue pixel in a red orange dominant areas).

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Maybe this thread helps you a bit.

You can see the 40% as base and a 6400 iso can have a 70% to denoise.
Base iso value’s lower to 20% or less. ( all seems the auto mode to be nondestructive for details of lower iso values.)