Digital BW, The Print

Hello Ernst,

>What are the best results with QTR and BO for the different  Dither 
>Algorithms ?  The effect must be more visible in BO printing and may 
>vary per printer and paper. I also wonder what looks most alike the 
>Epson driver in BO mode. Just curious.

I've been wondering that myself (haven't used QTR much yet, been
working only with the "Ordered" setting which is slightly
tighter/smoother than Epson) so your question made me go find out.  On
a 2200 w/ Eboni and my current QTR BO curve (still under development)
I printed a step wedge on EEM for each dither setting and compared
them.  All were with 2880 and "Faster" speed setting (more about that
below).  Here are the results:

-----------------------------------------------
Ordered - smaller patterns of dots than Epson's squigglies, slightly
tighter pattern, slightly smoother in appearance.

Adaptive Hybrid - tiny difference in pattern if you look hard for it
with the loupe, but for eyeball appearance is nearly indistinguishable
from Ordered.

Fast - Pretty much same as Adaptive Hybrid, but under the loupe I see
a tiny bit of dither banding.

Very Fast - Horrible!  Prints streaks of graphic patterns.

Hybrid Floyd-Steinberg - Surprise!  Very tight and smooth.  Noticeably
smoother to the eye compared to Ordered and Epson.

EvenTone - More surprise.  Ever so slightly smoother than Hybrid FS.
-----------------------------------------------

For a more practical test to verify the above, I printed a landscape
with clouds, an image that has always showed up BO weakest area,
smooth midtones.  It verified all of the above ramp observations. 
There is a place in the clouds with little swirling patterns that are
barely defined in Epson BO, are a tiny bit better with Ordered, and
are very crisp and clearly defined with HFS and EvenTone, with
EvenTone being a tiny bit the better of those.

I am delighted.  This is going to make a huge difference to BO lovers.
 Just on this one test print I can see it's an enormous improvement,
with a greatly reduced grainy look and retains the luminance.  Now I
just need to finish working on the curve.  It's still too blocked up
at the dark end.  I will post it as soon as it's done, probably over
the coming weekend.  Wahoo!  Imahappycamper.  Why didn't I try this
before???!!!!  Still need to test with other papers...

About the "Speed" setting: I printed a TrueTone ramp with Speed set to
"Better" (still 2880), and it messed up the ramp, introducing some
bumps and streaks into what had been a smooth ramp using "Faster"


Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm