(Please CC me)

I have what must be a very common problem, but I
can't seem to solve it myself. I prefer to use
linux, if possible.

I want to scan photos to preserve them. I'd like
high quality files.  If practical, they can be as
large as necessary to preserve all information. I
also want to convert these images to various
smaller images suitable for different purposes,
such as viewing quickly on a computer screen, and
also thumbnails. I am having some difficulty at
each stage. I have tried xv, imagemagik, netpbm,
and gimp. gimp in particular shows the problem of
very large, but low quality jpeg files that I
mention at the end of this message.

I have access to some HP scanner attached to
machine running NT. The installed program does not
reveal what resolution I am scanning at, only the
"magnification".  When I look at the resulting
image with, say, xv, I find that indeed, in
addition to being larger than I can view on the
screen, the image is scanned at higher resolution
(xv reports width and height in pixels). (Of
course, I would prefer that the size of the image
does not get huge just because I ask for higher
resolution, but that does not seem to be an
option.) By cropping and enlarging, I can see how
much "magnification" I need to capture more or
less all the information. For a studio photo, I
believe I need maximum "magnification" to get all
the information. Even a high quality picture from
a cheap camera seems to continue to reveal more
detail as I increase the resolution of the scanner
to its max. The resulting files can be from about
70MB to 300MB (24 bit tiff) depending on the size
of original photo. Am I misreading the results?
Do I really need such large files ?  Does anyone
have information or a link on what kind of
resolution is required to get an optimum scan of a
photo? I can't find anything on the web. I find
that these large tiffs can be compressed by about
a factor of 2 to 3 using bzip2.

I want to convert these to something viewable on a
screen or for printing on some cheap paper. It
appears that jpeg compression is a good choice for
photos. I have some basic orientation now on the
primary uses of the various compression formats
and the differences between the file formats and
compression algorithms. I find that different
programs give very different results when
converting to jpegs. I have tried xv, imagemagik,
netpbm, and gimp.  I have tried these programs
with several "quality" settings and other
parameters. (I typically use the "integer"
setting).  I would like a quickly loading jpg of,
say, 50 KB to 300KB (I don't really know). But by
the time I lower the quality setting enough that
the resulting file size is down to 3MB to 5MB,
which still takes a long time to load, the image
is seriously degraded. It looks much worse than
many 20KB jpegs that I have seen.  I suppose I can
make multiple scans, some at lower resolution and
then convert those.

These experiments are time consuming and I am kind
of working in the dark. I wonder if there are web
documents or books that discuss how to make high
quality scans of photos, and how to make high
quality lossy images for casual viewing.  I would
appreciate any information. Thanks!

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