Digital BW, The Print

Martin Wesley
http://www.borderless-photos.de/guests.html



----- Original Message -----
From: "jimhayes361" <jimhayes@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Tuesday, June 25, 2002 4:39 PM
Subject: [Digital BW] Re: pshop 6->7 VM (converts file differently?)


> --- In DigitalBlackandWhiteThePrint@y..., "Martin Wesley"
> <mwesley250@e...> wrote:
> >
>
> > Jim,
> >
> > I went through the steps above (except that I am working in Adobe
> RGB) and I
> > am not seeing any significant difference between 6 and 7
> >
> > For the PS7 version of my file I got Mean = 124.58, Std. Dev. =
> 95.52,
> > Median = 143
> > For the PS6 version of my file I got Mean = 124.41, Std. Dev. =
> 95.48,
> > Median = 143
> >
> > So there is some difference but much smaller than you are getting. I
> am
> > running Windows 2000. I wonder if it is image dependent.
>
> Martin I think this is the case exactly. I did a few images since I
> switched to PS7 and most were normal range prints- that is a more or
> less full tonal spectrum. It's really hard to see and I didn't think I
> had a problem at all, except the  small areas of shadow values looked
> a little posterized which I figured was just bad file manipulation on
> my part.

Jim,

I went back an dug out a grayscale that was shadow predominate and went
through the same workflow and got similar results:

For the PS7 version of my shadow file I got Mean = 82.30, Std. Dev. = 80.02,
Median = 44
For the PS6 version of my file I got Mean = 82.32, Std. Dev. = 80.07, Median
= 44

So it seems to be pretty consistent on my system at least.

>
> But I just went back and reprinted a print which is just about all
> shadows. For example your mean is about 124, about midrange, or, a
> fully balanced tonal image. My mean is 46.83 (ps6) or 45.57 (ps7). I
> also find it interesting that your histogram discrepancy is less than
> mine- is it due to darkness of print or do I have a setting wrong?
>
> Now this dark print I originally printed in Febuary. More than about
> 80% of it's surface is shadow detail, and it is one of my best prints
> as far as smooth shadow values/ transistions go. There is absolutely
> no posterization in the 3/4 tones which take up a lot of the print
> surface.
>
> When I compare it to the print I just reprinted yesterday in PS7- the
> new print is really bad. I have a close up of a hand with skin texture
> but it is very dark skin (varies Zone  III-IV) . in this new print
> instead of a textured hand I get something that is so posterized it
> almost looks like a cartoon.

This has always been a tricky area and is the weakness of the RGB separation
and Epson driver workflow. The application of the curves themselves in 8-bit
mode can totally trash your data. How do the PS6 and PS7 histograms compare
prior to applying a separation curve? Is the problem occurring when the mode
change is made or when the curves are applied?
>
> In addition I have a silklike drape that covers much of the
> background. Smooth in tonal transistion in the Febuary print,  in the
> print yesterday the tone breaks lighter suddenly on a fold of the
> cloth where it looks like it's broken out with measles.
>
> Anyway, my supposition (not even a theory yet) is that if you don't
> get exactly the same numbers in PS7 vs 6, even if they are off less
> than 1%, the file is still different than the one you fed to the
> printer under PS6. Perhaps the higher values around 70%k say are not
> as sensitive to small changes in the file data. But how can anyone say
> how much of a difference in the histogram values will affect what
> Paul's curves do to image?
>
> The only way to solve this is to first, make sure I am not overlooking
> something in my settings/workflow, and then when I get the VM ink back
> in, simply print out my dark "problem" print in both PS 6 and in PS 7
> and see if it does print shadows differently. This is the only final
> way to rule it out or in.
>
> However, I am gratefull for your giving me Culbertsons workflow
> notion, and I think I will go back to the puter and try it out.
>
> Sorry for the length. If you get a chance and have some time, try
> printing out one of your lowest key images and check for posterization
> in 3/4 tones. I don't know if it would show up in a step wedge, I
> suspect if one compared it side by side, 6 vs 7 it might.

I would think that anything like this would show up in a step wedge. So you
might want to start there.

As I recall you are on a 1280 and I wanted to point out that Adobe
PressReady works with the 1280 (it thinks it is a 1270) giving you full CMYK
control. Peter Lindman sent me some really great prints he did with the
MIS-VM set and I have seen Tyler's work with Piezo inks and Press Ready on a
3000. Of course you are then off on your own doing curves but you have more
control than trying to trick the Epson driver with the RGB curves.

I'm wandering. If you resolve the issue, which my trials would suggest you
can, please let us know what you find.

Martin

(snip)