Digital BW, The Print

>If you scan at a reduced resolution eg. 1200ppi instead of 4800ppi
(assuming
>that is the optical resolution), your scanner simply throws away
>three-quarters of the detail in your film, leaving you with just
one-quarter
>of the original detail.

I thought that ppi in the scan was relevant in determining the amount of
"detail" in the print but that detail in the scan was a function of the
scanner's optics and mechanics, not the ppi setting. I would expect to lose
detail in the print if for example I scan a 4x5 negative at 300 ppi and then
make a 16x20 print but I never thought that if the scanner is capable of say
4800 ppi and I scan at 1200 ppi I've necessarily lost  three quarters of the
"original detail" in the negative regardless of the size at which I print.
Or stated another way, I would have thought I could scan the 4x5 negative at
say 720 ppi with a 4800 ppi scanner and make a 4x5 print that has as much
detail as the scanner, printer, and paper are capable of producing, i.e.
that I wouldn't lose most of the detail in the negative by doing that.

"Printer drivers vary but probably you don't need to help it resample by
scanning larger than is reasonable. The (maximum ppi) will consume vast
amounts of memory for no good reason. . . So this article might make us
ponder why it is that we think we must routinely scan a photograph at
(maximum ppi)? We can't show that size on our monitor. Our printers cannot
print that much resolution. The photograph doesn't have that much detail
anyway. Our memory size doesn't tolerate it and our disk space hurts too. It
must be a macho thing to do it." Fulton, "A Few Scanning Tips," pp. 49 & 54.

However, I'm certainly open to being corrected, I don't claim to be an
expert. I just haven't before heard that the scan (as opposed to the print)
loses detail as the ppi is reduced below the maximum of which the scanner is
capable.

----- Original Message ----- 
From: "Bob Frost" <bob@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Monday, December 06, 2004 3:24 PM
Subject: Re: [Digital BW] Computing power



B,

For best results you should scan at the optical resolution of your scanner,
and then reduce the file size/ppi in Photoshop if you need to reduce it.

If you scan at a reduced resolution eg. 1200ppi instead of 4800ppi (assuming
that is the optical resolution), your scanner simply throws away
three-quarters of the detail in your film, leaving you with just one-quarter
of the original detail.

If on the other hand, you scan at 4800ppi and then reduce to 1200ppi in
Photoshop, PS doesn't simply throw away three-quarters of the detail, it
effectively 'averages' the 4800ppi detail to provide you with a new 1200ppi
image that more accurately reflects the original than just throwing pixels
away.

Bob Frost.

----- Original Message ----- 
From: "B. Campbell" <bellis60@...>



>Not much point in shooting larger formats if you plan to scan them at
>such low resolution that they produce the same size files as smaller
>formats.

Sure there is. If I did my job my larger negative contains better detail and
tonal range than a smaller negative.  I don't lose that detail and range by
scanning for a file size that produces the maximum dpi my printer driver
will allow at the largest print size it will make and/or that I want or
need.  In other words, there's





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