15 Apr
2009
15 Apr
'09
1:59 p.m.
Jan-Benedict Glaw wrote:
could
I think the confusion is in: 'on a fiche around 1" x 1.5"'
J-B read that as the size of the whole fiche (with lots of A4 images on it). I think you
actually meant that each page image is that size.
The truth is most likely in between: page images (on DEC fiche at least) are a bit smaller
than that, and also they are usually images of line printer size pages (A3, not A4). So a
2400 dpi scanner is about a factor 3x too low for acceptable quality. (And yes, that
ignores other issues like ability to hold the fiche flat enough and focus well enough.)
paul
On Tue, 2009-04-14 10:52:00 -0500, Jules
Richardson
<jules.richardson99 at gmail.com> wrote:
The DEC
ones I've seen are extremely high resolution - from memory,
something like 11 x 13 A4 pages on a fiche around 1" x 1.5".
If this is right, then there's a scale factor of about 1:90 to 1:100
involved. That should tell everybody why even a good consumer-grade
scanner will not do the job. To get the equivalent of a 300dpi scan,
you'd need to have about 30000dpi. Nothing any el-cheapo scanner handle. (Let alone the problem of getting the
sheet properly into the
light's focus.)
you are confusing linear pixel density with areal pixel density.
the 11"x13" fitting in 1"x1.5" implies a 11:1 scaling in density, so
300
dpi would be 3300 dpi. still very high for typical consumer grade
scanners. I believe 2400 dpi actual (not interpolated) is available on
decent models, though.