Archived posting to the Leica Users Group, 2002/03/27
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> > I'm confused about what your formula means. It says that th. dyn. range in > > *stops* = number of bits. > > No, that isn't true. You can't talk about 'dynamic range in stops'. Dynamic > range factors in the tonal resolution you require. OK, I think I see now. I didn't realise we use the same sort of numbers for both densities (light absorbtion in film or filters, which we can talk about in stops) and 'digital detail' meaning (log) how many steps betweem our system's black and white. > 256 shades of gray (8 bits) is usually considered sufficient to be perceived > as continuous tone, so theoretically the maximum Dmax any scanner requires > is just under 3. This would however require you to get the scan absolutely > perfectly right on the first pass. Doesn't this build in assumptions about the maximum brightness range of the final product? White compared to black on paper is only ever so-much different, but if we had a device that could display scenes like snow and wet black rocks in sunshine, then surely we would need more than 256 shades for a visually continuous tone? Perhaps rather than me asking a million basic technical questions, do you know of a decent basic reference on all this? Most of the stuff I've seen on the web is recipies for how to scan; I'd like to first understand what's really going on. Maths is no problem, as long as they define the terms. Michael - ---------------------------------- Michael Abbott lists@mabot.com (Theoretical physics, clueless about signal processing.) - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html