Nick Makris (nick@mcn.org)
Sat, 31 Jul 1999 05:57:57 -0700
Hello again,
Received the message below from Dan B. regarding output to your deskjet
printer - it says in effect that the formula, discussed in one of my posts
of yesterday, does not apply to output on an inkjet printer because they
(some, Epson 1520 in my case) use random dot printing (stochastic). Given
that is true, I would like to add that this particular printer will also
print halftones. I have determined that a Bitmap type of file will
automatically render a stochastic image on an inkjet printer (do I
understand this correctly?).
On the Epson 1520, at least on the PC/W98, the setup for the printer allows
for the printer default screening method or for manual control of screens
using LPI, diffusion, etc. Does this mean that the printer is able to make
a halftone even from a bitmap output??????? By the way, my 1520 manual
shows no reference to the word "Stochastic".
When printing a bitmap, when/why/how/what does one do to apply the proper
number of colors (posterizing) to create maximum resolution on output to the
printer or is there a meaningful consideration to be learned here? In other
words, when using a bitmap to print to an inkjet printer are there any
attributes associated with that type of file that will cause the printer's
resolution to be limited to something less than its maximum resolution - or
what is it about the bitmap that makes it work differently?
So, if you have any experience in this area please come forward with your 2
cents.
As you can see, I am verbalizing the newly understood process as I go
along - please bear with me.
Many Thanks,
Nick
-----Original Message-----
From: DanPhoto@aol.com <DanPhoto@aol.com>
To: nick@mcn.org <nick@mcn.org>
Date: Friday, July 30, 1999 12:18 PM
Subject: Re: More on the limits of Grayscale
>You said in your message...
>
>> begins to provide insight
>>to the idea that the max printer resolution as output on any piece (say
>>1440dpi) is limited by the combined use of number of grays (say 130 out of
>>possible 256) and the number of lines chosen for the screened output (say
>>130): Actual print output in dpi=(Screened output in LPI) X square
>>root(Number of Grayscale colors to be printed)
>
>Hi Again Nick,
>
>Remember, this formula has to do with conventional LINE SCREEN output and
>has nothing whatsoever to do with the kind of output you get from an
>inkjet printer like the Epson, which I assume you're using for tests
>given the 1440 dpi figure you mention elsewhere in your post. The latter
>uses stochastic screening, which is of course why the output is so good
>with an inkjet printer. Were it producing a 130 lpi output, you'd see the
>dot pattern with your naked eye. Even crude magazine output is generally
>higher than 130 lpi. Heck. even my book uses 175 lpi for it's screened
>output, whereas the cover image is printed stochastically.
>
>Anyway, just wanted to make sure you understood that those "rules" don't
>apply to random dot printing.
>
>Your posts are doing the list a service. And I agree with your
>recommendation for R.W. Scanning and Halftones, which is why I plug the
>book on page 278.
>
>Best,
>
>Dan
>
>
>Dan Burkholder
>P.O. Box 111877
>Carrollton, TX 75011-1877
>USA
>972-242-9819
>www.danburkholder.com
>
>
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