Digital BW, The Print

----- Original Message -----
From: "Todd Flashner" <tflash@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Friday, March 29, 2002 12:10 AM
Subject: Re: [Digital BW] Dynamic Range Definitions and Print Tones


(snip)
>
> Really? You selected grayscale, not 256 shades of color? The difference
must
> be in our graphics card. No matter.

No I can only get 256 color so I can't do the test.
>
(snip)
> > Unfortunately they did give any details of how the testing
> > was done. I hate newspaper articles about scientific tests.
>
> I'm sure it depends on how they test for this stuff. The test methodology,
> as well as the environmental conditions, will obviously have a huge
impact.
> I wonder if every institute even performs the same test, and if so, is it
> even a well designed test?

I am pretty certain that there is no standard for testing this as we would
be seeing results that were similar
>
> > I think that if it is some fixed number of say 256 you can have multiple
> > sets of 256 tones in an image that contribute to its impact. Say you
could
> > only differentiate 256 but you had 1024 tones. Your eye could see the
> > difference between 1 and 4, 4 and 8, 8 and 12, etc. You could also
> > distinguish between 2 and 5, 5 and 9, 9 and 13, etc.
>
> I have no idea how it all works. I guess the point is how many tones are
> needed to trick perception into believing all the tones are present. How
> many tones can be deleted before the eye notices them as missing. That
sort
> of thing.

Two things on that. You have the question of whose eyes and they do seem to
vary and we really don't want to be right on the edge. I think to fool the
eye you need some multiple of that number.
>
> I mean it doesn't even seem to be cut and dry as to whether staying in a
> 16-bit workflow and printing 16-bits through the Piezo driver makes a
> visible difference in print, and that can be the difference between 256
> shades and tens of thousands. (And to those who've heard that printing
> 16-bits through piezo does make a visible difference, I need to ask, did
the
> 8-bit version it was compared to contain all 256 tones? You have to give
the
> 8-bit version a fighting chance...)

The file may be 8-bit but I don't know what the print is. Since you have 4
or 6 inks and possibly 256 bits for each ink, the effect of the dither to
create additional tones, the ink drops may bleed into each other or the
paper. Once its dry what is there in terms of a number of tones is pretty
vague which is why I am thinking it may be a continuous tone without
discrete values. Which may also be why you can lose so many tones in the
histogram and still get a good print. I keep thinking there must be
technical papers on this by Epson or someone.

Martin