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Thread: Luminance noise reduction in C1: increasing contrast?

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    Member bcf's Avatar
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    Luminance noise reduction in C1: increasing contrast?

    The "Luminance" noise reduction slider is by default at 50, even for low ISO files. I noticed that, if I set it to 0, expecting the image to appear more sharpened, the image ended up less sharpened - or rather, upon further inspection, less contrasty (less local contrast).

    Does C1 increase local contrast "under the hood" when the luminosity noise suppression is increased?

    Anyway, I find that with luminosity noise reduction at 0 instead of 50, and the default sharpening settings, images look more natural: with luminosity noise reduction at 50, they are often exhibit too much local contrast to my taste.

    Does anyone see the same thing (I use a D700)?
    Last edited by bcf; 5th August 2014 at 06:40.
    -- Bernard

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    Member bcf's Avatar
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    Re: Luminance noise reduction in C1: increasing contrast?

    Fot instance, in the two attached pics: the first one has Luminance noise reduction at 0, the second one has it at 50 (default value) - and it shows more contrast (or local contrast?).

    Not very visible on screen, but if you download the pics and switch from one to the other, it's obvious.

    Or am I seeing things...?
    -- Bernard

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    Sr. Administrator Jack's Avatar
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    Re: Luminance noise reduction in C1: increasing contrast?

    My take is that removing L noise is most visible in the shadows -- and since noise grays up shadows, removing it will darken them. This in turn could lead to your impression of less contrast since with noise present, the blacks are possibly not as deep.
    Jack
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    Member bcf's Avatar
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    Re: Luminance noise reduction in C1: increasing contrast?

    Thanks Jack, I understand. That's a likely explanation.

    Actually we are at ISO 200 in this pic, from a D700, not much luminance noise to be seen. But the algorithm is still operative I guess. It is less easy to see the effect at ISO 1600 for instance, because then the noise is visible, and removing it makes the contours less clear cut, thus diminishing the apparent contrast.

    Anyway... I found this effect interesting because i often feel that the default rendering of C1 is too "sketchy", as if the edges were underlined. Decreasing the luminance noise reduction to 0 (when possible) reduces or eliminates this effect.
    -- Bernard

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