Archived posting to the Leica Users Group, 2001/07/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Austin writes: > Which means you need a scanner of 5400 SPI > to reliably detect your 53 lp/mm... Nope. 53 lp/mm times two = 106 lp/mm, or 2692 dpi. > How does that apply to this? The whole field of digital image capture and workflow is based on information theory, and it is much more difficult to avoid the theory in the digital realm than in the analog realm. (Information theory also controls analog information processing, of course, but it is possible to do things more empirically in the analog realm without ever directly being aware of the theory.) > You may be a wiz in "information theory", but > I'd suggest that you don't design any scanners > until you get a real understanding of the > mechanisms involved...or do design a scanner > and learn how it's done! You may be a wiz at designing scanners, but it sounds like you have a strong empirical basis for your knowledge, to the detriment of theory. The fact that a scanner you design might need more than 2x sampling to achieve some resolution does not mean that this is any kind of absolute rule. > No better teacher than experience. Usually a blend of theory and experience is best, IMO. > I have clearly shown, and I'd have to believe, > given your response here, that you agree, that > you need to sample at >2x to "reliably" RESOLVE > a line. Yes. But at 2700 dpi, you are doing precisely that for a resolution of 53 lp/mm (2700 dpi is actually 53.14 lp/mm).