[alt-photo] color separations in Photoshop

[Charles Ryberg]

 Folks--In Photoshop when I have an image (RGB) and use the channels box to 
make separations the resulting files are Grayscale.  I can, of course, 
convert them to RGB.  My problem is that after I apply my curve there is a 
difference between the images left grayscale and those converted to RGB.

    Now, I derived the curves using the common 10 x 10 square which was, of 
course, in RGB --so it seems likely that I should convert.

    I don't remember seeing this discussed anywhere.

    Advise (yes, I'll try both ways if I need to).

Thanks    Charles     Portland Oregon