Digital BW, The Print

I'm printing with vm inks on an 870 from a windows machine, and I'm 
using Paul's 870 curves.  For the most part, my prints have been 
excellent, but two prints have shown fairly serious posterizing 
toward the dark end of the spectrum.  Interestingly, this problem 
shows up with every single partitioned curve--that is, every curve 
except the simple, grayscale curve (gs1).  I've tweaked the curves so 
that I get a very smooth, even, 21-step wedge, but the problem 
persists.  After printing some very steep gradients, it appears that 
the posterizing occurs between 95 and 96%.  It seems that the black 
ink is being fed in too suddenly.  I can smooth things out by making 
a rather drastic cusp in the blue curve (lightest ink) at around 98%, 
but it's really hard to control photoshop curves on such a small 
scale.  Furthermore, such an extreme curve produces artifacts, 
especially when I try to adjust the other inks.  I should mention 
that these steep gradients print perfectly from a grayscale file with 
the gs1 curve, but if I convert the image to AdobeRGB (or sRGB) and 
use the gs1 curve (or even with no curves at all), the same kind of 
posterizing occurs as with the partitioned curves.     So maybe the 
problem has to do with printing from an RGB file.  Does anyone have 
any suggestions?

McKenzie

--- In DigitalBlackandWhiteThePrint@y..., "mckenzielamb" 
<mckenzielamb@h...> wrote:
> I'm printing with vm inks on an 870 from a windows machine, and I'm 
> using Paul's 870 curves.  For the most part, my prints have been 
> excellent, but two prints have shown fairly serious posterizing 
> toward the dark end of the spectrum. 

If you are using PS7 instead of PS6, just to rule out the greyscale 
PS6-->7 bug that was just discussed a couple of days ago, please 
search for that topic by searching for "print change confirmed" or the 
like...it is a fairly detailed and long thread, I don't think you can 
miss it. I even got posterization- and worse- in PS7 with Adobe98 
conversion, though it was nowhere as bad as with the sRGB conversion.

You see, PS7 converts files differently then PS6 does. I notice 
posterization in a very dark file, but when using PS6 it goes away. It 
is lessened by using Adobe98  in PS7 instaed of sRGB, but I still have 
some odd problems.
Jim H.

Thanks for your reply.  As it turns out, I'm still using photoshop 
6.  However, the problem does seem to be in the conversion from 
grayscale to RGB.  If I create a gradient in an AdobeRGB file and 
then print it without doing any conversions, it prints perfectly--no 
posterizing.  (Interestingly, conversions from RGB to grayscale seem 
to cause similar problems.)  I suppose I'll just have to work 
exclusively with RGB files.  Too bad: It's a waste of space and time, 
and it makes softproofing much less convenient.  Maybe I'll try using 
the Microsoft ICM conversion engine, though I don't suppose it will 
be any better than the Adobe engine.  It's curious that other's 
haven't encountered this problem.  I have to wonder whether I'm not 
doing something else wrong.

McKenzie
       
--- In DigitalBlackandWhiteThePrint@y..., "jimhayes361" 
<jimhayes@j...> wrote:
> --- In DigitalBlackandWhiteThePrint@y..., "mckenzielamb" 
> <mckenzielamb@h...> wrote:
> > I'm printing with vm inks on an 870 from a windows machine, and 
I'm 
> > using Paul's 870 curves.  For the most part, my prints have been 
> > excellent, but two prints have shown fairly serious posterizing 
> > toward the dark end of the spectrum. 
> 
> If you are using PS7 instead of PS6, just to rule out the greyscale 
> PS6-->7 bug that was just discussed a couple of days ago, please 
> search for that topic by searching for "print change confirmed" or 
the 
> like...it is a fairly detailed and long thread, I don't think you 
can 
> miss it. I even got posterization- and worse- in PS7 with Adobe98 
> conversion, though it was nowhere as bad as with the sRGB 
conversion.
> 
> You see, PS7 converts files differently then PS6 does. I notice 
> posterization in a very dark file, but when using PS6 it goes away. 
It 
> is lessened by using Adobe98  in PS7 instaed of sRGB, but I still 
have 
> some odd problems.
> Jim H.

Okay, though one other thing to double check is the MIS site...just a 
couple of dqays ago they updated curves and now use Adobe98 I 
think-and maybe for 870...
Jim H.



--- In DigitalBlackandWhiteThePrint@y..., "mckenzielamb" 
<mckenzielamb@h...> wrote:
> Thanks for your reply.  As it turns out, I'm still using photoshop 
> 6.  However, the problem does seem to be in the conversion from 
> grayscale to RGB.  If I create a gradient in an AdobeRGB file and 
> then print it without doing any conversions, it prints perfectly--no 
> posterizing.  (Interestingly, conversions from RGB to grayscale seem 
> to cause similar problems.)  I suppose I'll just have to work 
> exclusively with RGB files.  Too bad: It's a waste of space and 
time, 
> and it makes softproofing much less convenient.  Maybe I'll try 
using 

> the Microsoft ICM conversion engine, though I don't suppose it will 
> be any better than the Adobe engine.  It's curious that other's 
> haven't encountered this problem.  I have to wonder whether I'm not 
> doing something else wrong.
> 
> McKenzie