[geeks] Scanner recommendations?

[Geoffrey S. Mendelson]

On Thu, Feb 28, 2008 at 06:56:01AM -0600, Bill Bradford wrote:
> 
> For software there is only one choice:  VueScan

I would second that with a caveat. VueScan claims it produces
"accurate color". It does. Most people don't want accurate color,
on a monitor and often on paper it looks faded or washed out.

If for example, you were to make a video or photo of your hand in
reasonable lighting and then display it on your monitor and then
ask people to use the computer to make it "look right", they would
always make it too bright, too high contrast and too saturated.
Many would do it with a color cast, blue/red for women and
orange/yellow for men.

If you want an accurate repesentation of your photographs, then
it pays to get a color calibration system and get them as close
as possible. You can always "improve" them in Photoshop or a 
similar program if you want.

Vuescan is not IMHO a good program for documents. There are several
linux ones (which may have been ported to MacOS, I don't know) that
will read in all of your pages in a row and then do the same for
the other sides, assembling them in order. One of the programs
will run a program called "unpaper" which straightens out the images.

You can then produce PDF files of the scanned images or OCR the text.

OCR is not a panacea. Most OCR programs are 98-99% accurate, which means
at least one error for every two lines. 

I set up my scanner on a dual boot Windows/Linux computer and due to
hardware problems gave up. In the meantime I found that SANE (the 
Linux scanner access layer) did not support monochrome low res (300dpi)
scanning on that scanner. It took me a while to figure it out, I had
to look in the code to see that it was there and then email the author
who told me he never implemented it because of problems.

I wanted to use it because a 300dpi single bit scan, which is fine for
OCR (400 or 600 is better) or saving books, etc. took 15 seconds and
was a meagbyte of uncompressed data. A 1200 dpi scan was 4 times the size,
and you can imagine how big it became with color.

Unfortunately, I can't remember the name of the program, and without a
scanner, I can't verify it.

Note that if you scan a letter or A4 paper at 300dpi monochrome, and
make a compressed TIFF file using CCITT group 3 (fax) compression, it
will be less than 50k. Good enough to read and print out on a laser
printer, but small in diskspace.

If you are going to do a lot of paper, consider getting a document
feeder and if you are really going to do a lot, a double sided scanner.

When you scan photographs, the best resolution for printing is 250-300
PIXELS per inch. Printer manufacturers never specify PIXELS per inch,
only DOTS per inch which is quite different.  

Geoff.

-- 
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