Olympus-OM
[Top] [All Lists]

Re: Scanning (Was: Re: [OM] HCB - OM eqivalent to Leica M + 35/2?)

Subject: Re: Scanning (Was: Re: [OM] HCB - OM eqivalent to Leica M + 35/2?)
From: Chris Barker <cbarker@xxxxxxxxxxxxxxxx>
Date: Thu, 13 Aug 1998 11:16:46 +0100
Jan

If we are agreed that this is on-topic, I would like to know more before I
add a scanner and colour printer (probably an Epson 720/800) to my lovely
PowerMac.

>Basically, dot matrix printers use creative marketing. The 1440 you see
>advertised is a white lie. True, it can pack 1440 dots into an inch, but
>each one cannot be any one of the colors in the printer's gamut. Typically,
>such printers fill a 4x4 matrix with CYMK dots to achieve about 200 lines
>per inch for arbitrary colors.

Were we talking about dot matrix printers?  I thought that no one used them
for printing scans of photographs.
>
>Also, when scanning, you need to scan at a minimum of twice the desired
>output line grid to preserve its detail. This is the so-called "Nyquist
>number," and is why audio CDs are sampled at 44 kHz when no human can hear
>anything above 22 kHz.

Surely the sampling rate is that which the sampler samples (asks for
information from the player of music), while the hearing frequency is that
of the sound, i.e. different things.

>What does this mean? For "same size" work, scanning at above 400 samples
>per inch is a waste, and scanning above 200 samples per inch doesn't buy
>you much. The value of such high scan densities is if you intend to blow it
>up. You can blow up a 600 spi scan by a factor of three with little impact
>on the output.

This samples per inch confuses me (I know, that's easy!).  Is that the same
practically speaking as dots per inch (dpi)?  I understand from your next
comment that dpi will be different for different input or output devices.

>Personally, I sample at 300 spi for same-size printing, then run the Epson
>at 720, which is REALLY only 360, at best, on perfect paper.
>

Thanks
Chris

"The man who lives in the past is blind in one eye but the man who forgets
it is blind in both." Solzhenitsyn.



< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz