Archived posting to the Leica Users Group, 2001/07/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The recent POP Photo scanner review *measured* the resolution of the LS-4000 at 60 lp/mm. As I understand it, noise plays a major role in reducing the true resolution of a scanner down from the theoretical resolution (which would be 78 lp/mm for a 4000 SPI sensor). 60 lp/mm is still an impressive result, well up into the range that will resolve the benefits of good camera technique. Paul - -----Original Message----- From: Austin Franklin [mailto:darkroom@ix.netcom.com] Sent: Tuesday, July 24, 2001 9:06 AM To: leica-users@mejac.palo-alto.ca.us Subject: RE: [Leica] Scanning > Austin Franklin writes: > > > 2700DPI only approaches the limit of quite > > grainy films. > > 2700 dpi is 53 lp/mm. It is very difficult to achieve 53 lp/mm > with handheld > photographs because of camera shake (and most of my photos are handheld). I believe your premise is flawed. You need to sample at slightly more than 2x the maximum frequency you want to acquire. A scanner IS a data acquisition system. 53 lp/mm is 106 lines/mm, which, as you say, is ~2700 SPI. In order to assure that the scanner can actually "acquire" all the lines, both black and white (which is what a line pair is), you would need to sample at > 5400 SPI.