24 Apr
2015
24 Apr
'15
8 a.m.
On 4/24/2015 9:46 AM, Paul Koning wrote:
Why don't you actually try it. Also,
I'm assuming reading on a screen (where
I read most of my vintage manuals) vs.
re-printing. My screen resolution is
90dpi. Anything over that is pure
waste. Maybe you have better eyes than
I do, but I can't discern image quality
over 100-200dpi for printing.
- J.
On Apr 24,
2015, at 10:40 AM, js at cimmeri.com wrote:
On 4/24/2015 8:48 AM, Noel Chiappa wrote:
While smaller, I've always
found 1 bit b/w scans to be nightmarish to read (too much font detail is sometimes lost),
and forget about grayscale pictures and diagrams coming across intact. Grayscale is best.
The problem comes in overdoing the DPI. Even 90 dpi is good enough. 150, more that
sufficient. 300 or 600, total waste, but they are (obviously) the most accurate
renderings.
I would not call 90 dpi ?good enough?. The professional printing rule
of thumb is that for an n grayscale dots per inch halftone image you need 2n DPI
resolution. So 90 dpi is, at best, low grade newspaper resolution. A standard commercial
grade scan for good quality printing is 260 dpi or so ? which means 300 is certainly a
fine choice. 150 or below may well be acceptable if that?s the best you can get, but
you?re definitely compromising image quality if you do that. From:
shadoooo
I'm scanning at 600dpi grayscale, lossless
compression.
I've been scanning a few things too, and I found that 600dpi grayscale
produced absolutely enormous files (many, many MB's per page, for prints), no
matter what I tried to do, compression-wise.
600dpi black and white, followed by saving as TIFF's with CCITT Group 4
compression, produced immensely smaller files (small 100's of KB's for the
same pages), and they are quite readable (even the fine letter seems to be
readable - b/6 is quite distinguishable, etc).