
Originally Posted by
John Chardine
I remember a thread about this a while ago but can't find the link. Essentially the gist is that if you apply heavy-handed blurring to reduce noise in an area of an image with little detail that you get banding. Apparently a certain amount of random noise is important to give you smooth total gradations, but I can't remember the physics behind it.
You can try it yourself- make an image with some noise in the sky for example, then run over the sky repeatedly with the blur brush in Ps set to 100%. You will begin to see banding.