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Luminosity based selection for noise removal, how?

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  • Luminosity based selection for noise removal, how?

    Ok this may sound complicated but for the experienced PS user it should sound ok.

    It's easy to make a selection based on Luminosity in CS3..... Ctrl + RGB will select all brighter pixels, and inverting the selection selects all the darker pixels....

    ....... this is where I get stuck........

    I want to apply Noise Ninja to those darker pizels to remove any noise that is there, but even with that selection highlighted Noise Ninja still applies noise reduction to the entire image.

    Does anybody know how to restrict the noise reduction to just the dark pixels highlighted?

    Any help appreciated.


  • #2
    I'm by no means a master PS user but i'll give my thoughts.

    If you have the pixels selected that you want to apply the NR too can you not paste this selection onto a new layer and apply it on that layer only? Then surely you can overlay this onto the main file and adjust the setting of the layer and the opacity so that it comes through over the area you want the NR applied to?

    I myself don't actually use NR hardly at all for aviation so maybe i'm not the best person to ask. I know that Jid is very good with his photoshop wizardry so maybe he can help?

    Chris Sharps
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    • #3
      To apply a luminosity mask press ctrl+Alt+` or in CS4 ctrl+alt+2 just to confuse you. This applies a mask 100%light 0%dark. Invert the selection if you want it the other way - ctrl+shift+I if I remember correctly.

      I would personally look at applying noise reduction to a color channel, blue tends to hold the most noise so just apply your noise reduction to that channel?