First time using CS6 today, from CS2. I'd hoped that the Curves filter would be able to work in HSL (HSB rather), but it does not have this ability unfortunately. In fact, now I see that Photoshop doesn't really deal with HSB colour much at all. I want to be able to change an RGB image to a grayscale reflecting hue+saturation, because it's easy enough to get brightness by desaturating. A mathem... oh hey. It said it supports MATLAB. I'll look into that.