I'm a NN fan, using NN on slide scans in addition to digital, but maybe it's not the program for you. Software choices are good because people interact differently with UIs, influencing success.
This comparison establishes NN as a gold standard, but others are close depending on workflow http://www.michaelalmond.com/Articles/noise.htm
The NN manual is excellent at providing an understanding of noise, and tweeking the provided profiles. I find the Canon RAW files have much lower than expected Color Noise at ISO 1600.
Anyway, here is my condensed 10 step NN workflow. Maybe it will help you.
Pre-use set global NN program preferences:
1. Set RAM Cache allocation to about 20 Mb per MegaPixel. Thus 8.5 MP image file gets a 200 Mb Image Cache.
2. Set Sharpening to 0.
Using NN:
1. When there is a matching Profile downloadable from NN, use that profile as starting point. Check to make sure the correct ISO Auto Profile was loaded (right side under "after preview" image). If wrong, click "Load Profile" and navigate to correct Profile.
a. If processed preview looks good, proceed to Step 7.
b. If Auto Profile needs tuning, click little green cross icon, press "no" and proceed to Step 2. This is frequently the case, especially when high ISO images were "push-processed" by 1/3 or 2/3 in RAW conversion, or Levels or curves applied to shadow tones.
c. If there is no profile, and for scanned slides, Auto Profile the image and Proceed to step 2.
2. Add Selection Patches (left side) from areas of continuous uniform color that show luminance or color noise. Select patches not containing detail and uniform in color and brightness. Look at image at > 100% to see clearly. Select enough patches for a range of brightness and color levels, at least 100 x 100 pixels each. Avoid extremely dark or light areas. The luminance noise will be easier to see if you switch the view from RGB to Luminance mode using the menu pop up at bottom.
3. Go to Filter Tab, and set the Luminance Strength slider all the way to the right (20).
4. Set the Luminance Smoothness slider to the lowest level that results in smooth areas without speckling. May wish to start Smoothness at 0, advance it higher.
5. Now reduce the Strength slider until the balance between noise reduction and detail is satisfying.
6. Repeat steps 3-4-5 for Color Noise Strength and Smoothness sliders.
[I find the NN default settings of 10-10-10 too high, and usually end up with Luminance at 7-4-10 and Color at 5-2-10, even on ISO 1600 images. That's how low in noise PROPERLY EXPOSED converted RAW-16-bit TIF images are]
7. Set Sharpness and radiu to 0 again in the Plug-in window even set globally in preferences. Sharpen later in PSCS.
8. Save the Profile in the Noise Profiles Folder in PSCS. Annotate the Profile before you save it. Then for similar images, just "Load Profile" and go to 9.
[For Batch processing, once step 8 completed; name and annotate the edited profile. You can batch process a whole folder, walk away from computer for a while.]
9. Press Remove Noise button.
10. Use the Noise Brush - only in the Luminance Channel - to selectively undo detail loss fron noise reduction effects, particularly for hair, eye lashes, detailed fabric, etc.
Recognize you do not want a resulting images "free" of all noise. Destroys too much detail.
If you use a RAW workflow, the luminance and color noise reduction applied during conversion, like in ACR, influence whether the NN provided profile (created from camera .jpgs) needs tweeking.
I have used NN profiles as a starting point, and created additional profiles for indoor sports like
1-D MkII ISO 1250 Pushed 1/3
20D ISO 1600 pushed 1/2
etc.
Enjoy the trip.
Jack
