[filmscanners] Re: FW: VueScan file size

["" <focus@adnc.com>]

O.K., I can understand how VueScan can automatically compensate for IR channels 
and 16-bit,
but how does it predetermine the results of LZW (or jpg) compression? Since 
this can vary
wildly depending on the image contents, I'd assume you'd have to do the actual 
compression
to know the results.

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.

Roger Krueger

Bob Frost wrote:

> I thought that might be the answer as well, but when I looked at my recent
> version of Vuescan, it updates the image size that it displays at the bottom
> of the screen whenever I change the output file format, and the raw file
> that is saved is the same size as the processed file. I'm sure there is a
> simple explanation for this.
>
> Bob Frost.
>
> ----- Original Message -----
> From: <focus@adnc.com>
>
> What file format are you saving to?
>
> The size VueScan gives you is the raw image size. The disk file size can be
> different,
> mostly smaller, due to how the information is saved.
> I have seen very grainy/noisy scans that when saved as tiff/lzw exhibit what
> I call
> "negative compression"--the compressed file is actually larger than an
> uincompressed file!
> The other possible culprit is that VueScan gives you the option to save as
> 16-bit and/or
> with the infrared as a fourth channel.
> I'm not sure that either of these would show up in the raw size, but they
> would make the
> file size go up
>

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