Digital BW, The Print

Hello Andre,

>I've tried 2KBO printing on my Epson R220, following the steps you've
>described...

Good job of testing.



>...a BO print as control...
>First thing I noticed was that the light areas of the 2KBO prints had
>more density than the BO print. 

The main thing here is that my acv curve was created to match my 2kBO
print with my BO control print.  Our control prints may be quite
different (due to diferences among printers and whatever processes
were used to create them), and our 2kBO prints may have different
characteristics, for similar reasons.  So you probably need to make
your own custom curve.

The nice thing about using an acv curve for the fine tuning is that
it's so intuitive and somewhat WYSIWYG and we can see what effect the
change is having (as opposed to entering numbers in a points list
where we think is the right place and running a print to see what
happened - I've done both, and much prefer this method).  Open the
image in PS and temporarily attach a curve layer and load the acv
curve (don't save to disk or it will influence what QTR prints!).
  
Compare the 2kBO and BO prints and decide exactly where contrast needs
adjusting.  Click on that exact place in the PS image and a dot
appears on the curve - that's where the curve needs changing.  Make
the change, then save the acv curve (overwrite the old one).  Then
make a new 2kBO print, and repeat as necessary until the prints are
matched (then erase the temporary curve layer before closing the file).

An important thing, I found that once this curve was made it worked
for all my BO prints at least all I've tried so far, about 6.  None
have required a change.  So it seems to be a good match on a system
level.  Would be good if you van verify this.  

I'm not too surprised that my curve doesn't match perfectly for
someone else.  It's why my last sentence in the article was to the
effect that this is a starting place.


>The  LC/LM channels print had more of the grain effect, the K/LM 
>print less grain (?) with the BO print being the smoother. 

I don't know what to say here.  I can't test it because my K channel
is dead (the only reason I got into this was because of that).  But
there's no question that my 2kBO prints are far smoother than the
original BO ones.  If that's not true for you...well that's fine. 
Just go with whatever gives the best results (you do have Speed
setting at "Better", yes?).  You've taken the trouble to do the tests,
that's what counts.


>All prints had the same tonality.

Do you mean color tone?  That's odd, because my 2kBO prints are
noticeably warmer than the BO ones.  Is there a tone difference
between K/LM and LC/LM?


>But then I noticed paper white (no ink) in the two 2KBO prints at
>exactly the same spot: an outdoor light cover with strong horizontal
>lines and also around a lozange shape street sign. So I printed again
>on EEM (warmer tone) and the same artifacts appeared at exactly the
>same spots. Another BO print did not show these artifacts. Printed a
>nozzle check again just to make sure. 

I haven't seen any introduced artifacts.  The 2kBO prints have much
better resolution of fine detail (at least mine do).  Perhaps that
artifact is in the image and BO just doesn't resolve it...just
grasping at straws here, I have no explanation for it.

I hope others will try this and report results.

Regards,
Clayton


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