Oh, and sometimes Vuescan can get more bits out of the scanner then the original scanner driver.
On Sat, 2004-02-14 at 00:27, Frits W�thrich wrote: > Did you use Vuescan to create compressed TIF files, or did you have them > created uncompressed? > > On Fri, 2004-02-13 at 20:36, Mark Cassino wrote: > > At 10:58 PM 2/12/2004 -0500, Herb Chong wrote: > > > > >nothing is broken. your scans are picking up more noise in the extra bits. > > >there is much less run length correlation in the scan lines in a 16-bit > > >image compared to an 8 bit image. this tells you how much random noise is > > >present because of film grain and noise in the scanner. you should try the > > >same scan in multipass mode (assuming your scanner supports it) to see if > > >the files compress better or worse. try at least 8 passes. if your files > > >then compress better, you have shown that your scanner has mostly noise in > > >the least significant bits of the scanner A/D converter in 16-bit mode. > > > > That's interesting - and I ran some tests that confirmed it. I scanned the > > same slide in Vuescan, once with one pass, once with 16 passes. Both > > uncompressed scans were 138,016 KB. But, after saving them as 'compressed' > > tiffs, the single pass scan ballooned to 149,736 kb, while the multi pass > > scan only increased to 139,116 kb. The same scan, scanned on Canon's > > FilmGet software, went from 138,001 kb uncompressed, to 153,917 kb > > compressed... > > > > I guess this raises the question - should I even bother with 16 bit > > scans? Is there any way to really test the difference in quality? This > > makes me wonder if 16 bit files are a waste of time and disk space... > > > > - MCC > > > > ----- > > > > Mark Cassino Photography > > > > Kalamazoo, MI > > > > http://www.markcassino.com > > > > ----- > > -- Frits W�thrich <[EMAIL PROTECTED]>
