Archived posting to the Leica Users Group, 2007/08/18
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On another list someone complained about the "posterization" and aliasing encountered in scanning Tri-X film. Here is the quote: "both my 2880ppi and 4000ppi film scanners posterize my Tri-X negatives... which makes sense. there is also nothing you can do to remove sampling errors after you scan. My early analysis of Tri-X grain showed that it has strong frequency content around 4000ppi so when my scanners sample at around half the Nyquist frequency the aliasing is just a fact of life. With finer grained films, the grain is still aliased, BUT since the signal to noise ratio is so much higher the actual useful *image* data is not lost and *luckily* the new aliased *grain*, while not an accurate representation of the original, is still aesthetically pleasing." Can someone explain what he means in plain language? I've scanned hundreds of Tri-X negatives with my Minolta Dimage 5400 scanner at 4000ppi, and, apart from the inevitable dust spots on poorly stored negatives, I have yet to see what he means. If there is a problem, is the scanner software correcting it automatically? Larry Z