Extending off of Erik's post, what I like to do first - while targeting all the channels - is to turn the eyeballs off of all the color channels, except for the blue channel, as this allows me to see the noise artifacts usually associated with the blue channel due to things such as (but not limited to):
1. The insensitivity the CCD has towards blue.
2. Artifacting introduced when bringing in an image from a digital camera that has gone through the 3 phases of the jpeg process (division into the 8x8 blocks/adaptive discrete cosine transform applied, quantization, and entropy encoding).
Viewing the blue channel autonomously (with all the channels targeted), I'm able to dial in the correct amount for the both the median and/or gaussian blur filter. The correct amount being that neccessary to remove the objectionable artifacting/noise without softening my image too much.
The net benefit of dialing the numbers in to the individual image, instead of relying on one setting, is that:
1. Since all images are unique and present unique problems, you're addressing the specific needs of a particular image.
2. Too high of a setting will A) Shift the colors (irrespective of the color blend mode), and B) soften the detail too much.
To best illustrate this, place color samples on key tonal areas of your image and try an individual approach to the image. Notice the color values before and after.
Then try the higher numbers approach and notice the larger spread of color shift and softening associated with this method.
On my 300 PPI images, I've usually gone no higher than Median setting 3, and Gaussian Blur 1.5. Although your freeway mileage my differ.
Erik, I just checked out your site, your work is amazing!!
[righton]
I love the Mod Squad reference, way cool. which Mod Squad tv show member do you best associate yourself with?
This is a great site, everyone's very friendly!
Cheers!
Rick Miller
Enhancing skin and jpg 
Linear Mode
