From: Nick Makris (nick@mcn.org)
Date: 11/09/01-04:01:08 PM Z
Mark,
The Piezography RIP will be unavailable (ie, grayed out) unless you have
converted to grayscale mode. I believe this means 8 bit (256 colors).
Nick
----- Original Message -----
From: <Ender100@aol.com>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Friday, November 09, 2001 1:34 PM
Subject: Re: Re: large ink-jet printers
> Hi Joe,
>
> what you say makes sense. Since digital images are limited to 256 shades
, a
> step wedge that includes 256 levels is going to have a posterized effect.
> There is no way to get around this. But you can do a couple of things to
> minimize the apparent effect.
>
> 1. If you are using a gradient in an image (adding it in), limit the
length
> of the gradient so that the bands are very thin and thus lest noticeble.
>
> 2. Use Gaussian Blur slightly to mask the effect.
>
> 3 Use a small amount of the Noise Filter to further dither the edges of
the
> gradient.
>
> I do know that you can send 16 bit files to a printer using Cone's
> Piezography system and with the use of quad blacks you should be able to
> render more than 256 shades, however I am not sure that the Piezography
RIP
> allows this...it may just convert the 16 bit to 8 bit... I think I will
ask
> them about that.
>
> Mark Nelson
> In a message dated 11/9/01 2:20:13 PM, Smieglitz@aol.com writes:
>
> << Mark,
>
> The original file was a series of test gradients (0-255 levels) and
squares
> (n=101 at 1% ink intervals) generated in Photoshop.
>
> I have had some initial success using the 1160 output with Cone
inks/driver
> on Pictorico OHP for making digital negatives for use in gum bichromate
> printing. Jeffrey tested my files' utility for platinum printing. I do
not
> see the posteriztion effect he speaks of with my unaided eye (either
> onscreen, on a lightbox, or in a gum print), but I suspect he is being
much
> more critical than I and is certainly using a process and paper which
would
> reveal minor posterization better than multilayer gum image on
dimensionally
> unstable rough-textured paper. (My eyesight has also deteriorated
slightly
> in the past couple years which may also have an impact on discriminating
the
> effect he speaks of.)
>
> The bottom line is that we are comparing apples and oranges. I would say
the
> process (with a curve applied) is an excellent option for gum printing but
I
> leave the assessment of it's utility in other processes to expert printers
> (e.g., Jeffrey) familiar with the nuances of their cherished media. I
have
> not tried the 1160 negatives in other processes.
>
> I will add that previous generations of Epson printers (e.g., 600, 1200
> series) could not produce results I found acceptable for cyanotypes and
van
> dyke brown, but were acceptable for some gumprints. The 1160 combo shines
by
> comparison for gum negatives. But, as others have noted, there are some
> issues with ink clogging, fragility of the output, etc. that need to be
> resolved before I'd call it a perfect system. For gum printing I find it
> "good enough" for what I have in mind. (Of course, some gum printers use
> high-contrast Kodalith negatives for effect, intentionally looking for
major
> posterizations. "Whatever floats your boat"...)
>
> Film is still the benchmark.
>
> Joe >>
>
>
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