was: More on the limits of Grayscale now insight into how printers work


ken (watsok@frii.com)
Fri, 30 Jul 1999 11:58:14 -0600


I hope I can clear up some thoughts on how printers work and how to
determine what is actually happening on your machine.

First lets talk about scanners. If you really want to scan in an image at
the highest resolution you can get it is sometimes necessary to lie. That is
to tell the Scanner install program that yes you do have 3000dpi or some
other very fine dot pitch printer. This will help the scanner to default to
high res mode. Some scanner software will make it difficult to scan in much
over 300DPI if it thinks you have a 300 DPI printer. ( 600 DPI divided by
the three colors equals 100 dpi actually printed) so why scan in at a higher
resolution and waste memory etc? Re install your scanner software if
necessary to get high resolution scans to start with.

If this was already considered the next issue is to see if , in fact, your
printer is printing at the resolution you want. To do this go into your
image program and make a test sheet. For example put dots or lines an exact
number of pells apart. Then print you sheet, The spacing will most likely be
to small to actually measure with out some optical help. Use your scanner
again, scan in the printed test page and view the file in your image
software. Count the pell spacing and see if the printer did print as you
specified. If not well.... that may be to printer / software specific for a
general post.

In general Laser printer always print at the specified resolution. It is the
software that is between your stored image and the printer that may be
causing problems if any.

-----Original Message-----
From: Judy Seigel [mailto:jseigel@panix.com]
Sent: Friday, July 30, 1999 10:51 AM
To: alt-photo-process-l@skyway.usask.ca
Cc: alt-photo-process list
Subject: Re: More on the limits of Grayscale

On Fri, 30 Jul 1999, Nick Makris wrote:
> So, the moral of the story is use fewer colors and fewer lines in the
above
> formula to force the desired printer output. In the above formula
> 130Xsquare root(130)=1482 and therefore the max printer resolution (1440)
> will prevail. In my reading, I have found that the numbers used for
colors
> (130) and LPI (130) above are acceptable for many outputs. Test, Test,
> Test!!!!!
>
> As with all investigation, some questions remain unanswered. In this
case,
> I don't understand what the association between LPI (as in screened output
> or halftones) and that of stochastic output which supposedly has no
defined
> lines.
>
> If you have any answers, comments or corrections, please post.

Nick, you touch on, or at least evoke, what I have myself noticed --
although my understanding to date is still at what I'll call an
*early* stage...

No matter what resolution I scan at or work in, the printer makes up its
own "mind" -- and does NOT send me an announcement. My current printer
(about to be augmented by inkjet) is a laser with only 4 mb of memory. I
gather that that's the limiting factor, at least with the laser.

But in any form of printer is there a way to make it reveal what
resolution it's actually printing in?

Judy



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