Digital BW, The Print

I think this is a good point.  There are a lot of reasons for variations.  Just in the 
printing the dithering has a pseudo random component.  Which jets are used for the
particular area you are measuring will most likely be different.   Printer variation is
there but its hard to characterize.

Anyway, I decided to try this on my 2200-NK7.  A 51-step does show some choppiness
but curiously the posted reads had most of the problem in the lighter areas where as
mine showed more in the darker end.  There's a Photo Rag curve in the set that I created
on my 2200 using QTR as opposed to the supplied Piezo curves -- it's the one starting
with K7 instead of NK7.  At 1440dpi this also shows choppiness mostly in thee dark
region.  I have two suspicions on the issue.  First, is just that the large number of inks
puts a more critical burden on all the transitions from ink to ink.  Since there are more
transitions and they happen more steeply.  The other is the variable dotsize transitions.
This isn't an issue for the 2200 at 2880dpi but does show up in 1440dpi.  My 7500
has always been a lot smoother even before linearization, and the K6 inks bear this
out too.  So I've made some changes to dotsize transitions.  I've usurped the old "Fast"
dither algorithm which wasn't particularly good to try this out.  Of the various print
methods, using the K7 curve at 1440dpi (or super) and the Fast dither I get the 
smoothest and straightest overall curve.

So for anyone who wants to experiment, try the K7-PhotoRag profile and the Fast
dither.  I'd be curious how this works on other printers. 

Roy


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "wwodets" <odets@c...> wrote:
>
> John-
> 
> In a recent test that Paul and I did we found that there was 
> significantly more variation in consecutive prints than in the 
> consecutive readings of any given single target. He was using a 220, 
> me a 4800.  The print-to-print variations were not great, but my 
> memory is that they were about twice the reading-to-reading 
> variations.  And let's not even mention consecutive prints in Dektol. 
> 
> Walt
> 
> 
> --- In DigitalBlackandWhiteThePrint@...m, "John Moody" 
> <moodymz3@y...> wrote:
> >
> > And....  If you print the same target three times, you will get 
> slightly
> > different results; small, but real.
> > 
> > So that suggests, when getting down to the final tweaks, printing 
> more than
> > target, give proper dry down time, measuring each target more than 
> once, and
> > averaging all the measurements.  A nozzle check before each target, 
> and
> > after the last, for the overly obsessive. :-)
> > Putting them all into a spreadsheet allows finding, and correcting, 
> the
> > occasional outlier before averaging.
> > 
> > I'm sure this procedure is not for everyone, but, there it is....
> > 
> > Best regards,
> > John Moody
> > 
> > -----Original Message-----
> > From: DigitalBlackandWhiteThePrint@yahoogroups.com
> > [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of 
> Greg
> > Sent: Thursday, December 01, 2005 7:53 PM
> > To: DigitalBlackandWhiteThePrint@yahoogroups.com
> > Subject: [Digital BW] Re: Low Dmax on Epson 2200 with K7 inks 
> response
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "joshhackney"
> > <joshhackney@g...> wrote:
> > >
> > >
> > > Greg,
> > >
> > > Actually, there are 3 reversals between steps 26-28, 32-34, and 
> 38-
> > 40 on the 51 random
> > > step target data.
> > >
> > 
> > 
> > 0.1 L? That shouldn't be big enough to cause a problem. Maybe the
> > flat spot is making it trip. But 0.1 L is within the hardware's
> > tolerance, and if you measure the same patch several times without
> > measuring any other patch, you'll see an even bigger difference.
> > 
> > 
> > 
> > 
> > 
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