I also wanted to mention that I have come up with a method that applies to Olympus high ISO images. I find that on both my E-510 and my E-3, I end up with white spots with many of my high ISO shots and those spots become even more visible after clean up in Neat Image. It seems to be the way with the Oly sensors. Now the thing is that while these white specs (sensor noise) show on screen, I have found that they do not show when I print the images so it's kind of non issue unless I only view on screen or judge them in that fashion.
Even so, I played around with a bunch of different noise filters to see if I could get rid of them with having to put a lot of much effort into the process and something that was effective - - - and this method I came up with seems to work pretty well. What I did (in Photoshop) was create a duplicate layer of the image : apply Filter > Noise > Median and set the Radius to 1 pixel. This eliminates the specs and slightly softens the noise on the whole image which may be fine for some shots. However I wanted only the white specked areas affected while leaving the rest sharp - so changed the Blend mode of the duplicated layer to "Darker" - - - VOILA.
It works perfectly on most images. I did find that on the odd one, it would leave a very slight black outline around where the white spec was - but it is hard to see and would not show up in normal printing. At any rate - I applied it to all images here. I have made an Action so that it can be applied quickly to my image files.
I have a 100% crop from a file to show the effect:
This is the the crop straight from the 3200 ISO camera file with no processing:
This is what it looks like after Noise Reduction (the white specs become more noticable:
And this is the final result after applying the Median filter:
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This is the FULL FRAME image that the crop was taken from - shot at 3200 ISO : 1/125'th @ f4 :
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