Can you walk me through the steps in trying it on a single channel. Also, how much gaussian blur do you use. I'm new to CS4. I'm working through Scott Kelby's Book right now
Thanks
Kirk
Sure, no problem. In CS4 you have a "channels" panel in your tools (Layers/channels/paths). If you don't see it, go to menu item "Window, and click on channels. Assuming you are working with an RGB image, when you click on the channels tab, you will see the RGB image, then the ®ed, then (G)reen then blue channels separately. Take a look at each of the color channels to see if the noise is more apparent in any one of the channels. I find it is usually the red channel which is most disruptive in low light shooting.
Highlighting that channel, run the PS4 noise reduction. Use as much as you need, but be aware you will sacrifice sharpness in that channel if you hit it hard. Use just enough to make the noise acceptable (look at the preview screen). Sometimes using a touch of gaussian blur will confuse the eye enough that it does not perceive the errant pixels as noise. Use it sparingly, but experiment... always experiment with PS4. If you create layers for every step, its easy to go back later on. (Scott Kelby will explain that to you if you don't know that already).
I mentioned switching to LAB mode to do your sharpening because in LAB you can target the luminance channel only which is where you definitely want to do any sharpening if there is color noise in your image. Once you convert the image to LAB (Image, Mode. LAB Color) choose the L channel as you did earlier and run sharpen. Then switch back to RGB (image,mode,rgb). I hope this helps.
There are many other ways to work with noise (even books about it), but this should get you started in a fairly straightforward manner.