toss my fellow skrewhead
i may be a lil late on this (they call slow for a reason, my i mean well haha)
but i saw this on here
http://photoshopcafe.com/tips.htm
(look under the girl with scanlines)
and thought of you if this helps you understand more
Want to use RGB Filters while working in CMYK?
As you know some filters like the render filters are disabled in CMYK. Here is a neat tip, work in RGB mode with CMYK preview turned on. CTRL/CMD+Y build your file as normal then when you are finised, convert it to CMYK. This will allow all the filters to work, give you a smaller file size to work on (used 1/4 less memory) and you won't "lose" your colors when you convert it. Only use CMYK for going to a commercial printing press.
hope that helps?