matthew writes ... > On 18 Nov 2004, at 22:56, Martin Orpen wrote: > > > on 17/11/04 11:59 am, matthew ward wrote: > > > > ... > > Even Photoshop lies about bit depths. > > It uses a rather odd 32,769 levels! > > Maybe (for legal purposes) they are claiming that 15-bit +1 is the > > same as 16-bit? > > It is. > > Now I am getting very confused about this thread, but here goes nothing: > > if you want to express something to between 32,769 and 65536 levels on > precision, you need a 16 bit environment to do it in. If you want to > express something to 32,768 levels of precision you could get away with > a 15 bit environment....
I believe your confusion may stem from the fact that when PS refers to 16bits they actually refer to the 16bit format. The 16bit format is standard, and it contains 15bits of data ... and in fact may contain 10bit data, 12 bit data or 14bit data (and I suppose even the odd bit depths are allowed). I believe PS avoids a full 16bits because for many platforms (if not all) the 16bit format is designed to be for a signed integer ... i.e., -32,767 to +32,768. Since negative numbers do not make sense as pixel values, hence PS employs 15bits of information. hth & cheerios ... shAf :o) Avalon Peninsula, Newfoundland <www.micro-investigations.com> =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
