Tom Maugham posted his original question on the comp.periphs. scanners
newsgroup "I just scanned a negative and got the following information
from VueScan: "5576 x 3669 pixels 4000 dpi 1.39 x 0.917 inch 92.1 mb".
The size of the file on my hard drive is 119.885kb or about 119.9 mb.
Why the discrepancy between what VueScan says the file size is versus
the size on the hard drive?"
Ed Hamrick responded: "VueScan just guesses what the file size will be.
Different images compress differently. For instance, if an image
contains mostly sky, it will be a lot smaller than if it contains a lot
of image detail."
Back here, Roger Krueger <focus@adnc.com> commented: "Speaking of odd
compression results, I got a weird one with experimenting with JPEG 2000
yesterday--on a 620MB raw file, JPEG 2000/lossless was 320MB, JPEG
2000/quality 100 was 380MB! And is there any faster way to do JPEG 2000
than the Photoshop plug-in? It takes upwards of 4 hours on my G4/400 to
save a 620MB raw size file. The same file takes under 3 minutes as a
tiff."
------------------------
So, when someone again asks one of those ridiculous 8-bit-vs.-16-bit
questions, you'll have another reason to go with 8-bit. <G>
You might try the Photoshop plug-in for JPEG2000 from
<www.fnordware.com>. It is available for Mac, but I don't know which OS,
and the price is right. How are you getting 640MB files? Are they
10,000x10,000 pixels x 3(RGB) x 2(16-bit, 2-byte), or they smaller with
lots of layers?
On the original post, 5576x3669x3(RGB)x2(16-bit) would be 119,873KB or
117.06MB. (Don't you just hate that!) LZW compression (see
<>) does depends on adjacent
same-values to do compression, and 16-bit files evidently have very
different adjacent values and compress very poorly with LZW. You can
Google "JPEG 2000" as easily as I can to find out more on that subject,
if you're interested.
Preston Earle
PEarle@triad.rr.com
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