Scanning (was Re: recent acquisitions for the House of VAX

From: Jim Battle <frustum_at_pacbell.net>
Date: Tue Sep 11 04:05:09 2001

At 02:16 PM 9/10/01 -0700, you wrote:
>This topic has gone over the list a few times, from experience, the "best"
>scans are 600 DPI black and white compressed into PDF files. This achieves
>exactly what is needed, get the data without a lot of excess. The KA655 TM
>that is on the DFWCUG site appears from the PDF to be 100 DPI/8 bit (note
>that's 800 bits per inch net and the result is harder to read) I'll add
>scanning this manual to my list. They don't appear to have come up with a
>'standard' for their scans. That would help too.
>
>--Chuck

I agree that 300 dpi _at_ 1bpp is superior for text and line art than 100 dpi
_at_ 8bpp, but I think your math is askew. You need to compare the # of bits
per sq in, not inch. So 100 dpi _at_ 8bpp is 10KB/in^2, while 300 dpi @ 1bpp
is 11.25 KB/in^2. For text and line art, though, the 1bpp image will
compress a lot better.

And if, for some reason, you want to scan line art and text in gray scale,
4bpp is plenty enough. Use 8bpp only for continuous-tone images.

-----
Jim Battle == frustum_at_pacbell.net
Received on Tue Sep 11 2001 - 04:05:09 BST