It is my understanding that flatbeds generally do not pick up the detail
that a filmscanner does at the identical resolution. Since there is less
detail there are more areas of 'sameness' which, I assume, uses less space
for the JPEG algorithm to describe, whether compressed or uncompressed.
Make sense? I don't know but this sounds logical.
----- Original Message -----
From: "Lynn Allen" <email@example.com>
Sent: Sunday, May 27, 2001 10:23 AM
Subject: filmscanners: Size differences, JPEG
| Here's a question for Lawrence and others who might have 1200ppi flatbed
| scanners (or similar):
| Have you noticed that JPEGed flatbed image files are considerably smaller
| than the same pictures scanned with your filmscanner?
| I've noticed that scans scanned from prints with HP PrecisionScan and
| JPEG-compressed about 30% are about 1/3 to 1/2 the size of the same
| with the same parameters, scanned from a neg with other programs. It's
| a curious anamoly, but it's hard to figure out just what's going
| and previous discussions about "losing data" have made me wonder about it,
| and I wonder if other people are seeing similar results.
| I realize that the 6300's 1200ppi will produce about 44% less data than my
| Acer's 2700ppi--on a "linear" count, that is. But with both pictures going
| to the same size, at the same resolution, at about the same rate of
| compression, I'd think the difference would be less.
| The "lost data" doesn't seem to be significant at *normal* monitor
| resolutions--little more than the difference one observes from one imaging
| program to another. Perhaps my "off-line flatbed" has just given me too
| much time to worry, and I should be spending more time with a fishing rod
| my hands. :-)
| Best regards--Lynn Allen
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