From a previous post...
Try this in LR (should take less than 10 seconds)...
1. Open the DNG file in the DEVELOP module.
2. Open the DETAIL dialog box and go to the Noise Reduction set of sliders.
3. Press the "Alt" key on your PC to turn the image to B&W, then with your mouse pointer, push the Luminance slider to the place on the scale where the noise speckles start to fade, then adjust to suit your fancy (some like to leave a few speckles to keep the image from looking plastic...). Be patient as it may take a moment for the effect to become apparent.
4. Press the Alt key, again and adjust the COLOR slider to remove the color speckles. Again, be patient as it may take a moment or two for the color speckles to dissolve.
5. Go to the SHARPENING set of sliders (above the NR set in the DETAIL dialog box).
6. In your mind, subtract the Luminance adjustment number from 100 and enter that calculation into the AMOUNT slider's adjustment result box. For example, if your Luminance number was 30, enter 70. Notice that the luminance noise you erased earlier has returned. UGH ! Get rid of it by...
7. Press the Alt key on your PC, again, and adjust the MASKING slider to the point that your image appears to be a B&W line drawing.
8. Release the Alt key...
BINGO ! You have killed the image noise AND sharpened it, as needed to fit your taste. Now, let's get that pesky WB under control...
Read more at:
https://www.pentaxforums.com/forums/172-pentax-k-3/283047-wow-i-didnt-think-h...#ixzz3UG4Hbj5y
Also, check this out...
Good luck & cheers... M