"John Francis" <[EMAIL PROTECTED]> wrote: >Mark Roberts mused: >> >> Anders Hultman <[EMAIL PROTECTED]> wrote: >> >> >Shel Belinkoff: >> > >> >>What are "quantization effects?" >> > >> >The effect that comes from that you only have distinct levels to play >> >with, and that subtle changes have to be either on or off. >> > >> >Assume 8 bit gray scale. That means 256 distinct shades of gray from >> >0 (full black) to 255 (full white). >> > >> >A change from one shade to the next, say from level #240 to #241 is >> >very small in percent, but if you go from shade #1 to #2 it's a 100 >> >percent increase. >> >> Only if you're using a linear scale. > >Which we were, originally - we were discussing digital camera sensors, >which are pretty much linear response devices.
They are linear response devices, but that doesn't mean they have to use linear quantization. As far as I know, all film scanners use logarithmic quantization. (Though my Minolta and Kodak scanners both have an *option* for linear quantization, I can't see why I'd ever use it.) I don't know why a digital camera would be set up to use linear quantization, though I admit I have no knowledge of whether they do or don't. -- Mark Roberts Photography and writing www.robertstech.com
