I don't experience any of the problems you seem to have. I can split 8 and 16 bits-per-channel RGB images to R,G and B channels without any need to previously convert to CMYK. I can also switch from 0-255 to percent black in curves.
My working environment is CS4, Win 7, 64 bit AMD dual processor.
On Tue, Dec 1, 2009 at 11:57 PM, Charles Ryberg <email@example.com>
I've been away from printing for many months, w
orking on an audio project. In the meantime, I upgraded to CS4. My current problem is that I used to make separation negatives from a RGB file. Now, as far as I can tell, CS4 makes me convert to CMYK before I can make separations. Am I doing something wrong? Did CS4 hide the process as it did with some others (making it impossible to switch between 0 to 255 ink and % ink in the curve dialog for instance).
Any help is appreciated.
ps I did keep up with the messages while I was graphically inactive.
Yours Charles Portland OR