QTR-Quadtone RIP

Hi Tom,

Is there any advantage using the 51-step wedge over the 21-step when
> creating profiles for the Epson R2400 ABW mode? I'm using the Spyder3
> spectro.
>

While not used with ABW, my experience with the 51-step test strips was not
very positive.  I'm not sure why, but the results were usually not as smooth
as with the 12-step.  I ended up often getting a "see-saw" pattern in the
final.  I thought part of the problem may have been that with so many small
steps the effects of rollers and other causes of minor fluctuations had too
much influence.  So, I tried vertical 51-step test strips.  I ended up
giving up on these also.  The bottom line is that I have found a good
21-step in sufficient and the 51-step was not an improvement.

And what about random ...
>

A good, averaged random might be very good.  It would average out some of
the inevitable fluctuations.  Offsetting this is that I think most use strip
reading for these, and my tests indicate that strip reading is not as
accurate as individual, manual readings.  Additionally, I find the smooth
ramp on top of the 21-step I use to be very helpful (Jpeg version at
http://www.paulroark.com/BW-Info/21-Step.jpg).  If you see what looks like a
bump or vertical line in that ramp, you've got a problem, and it may be one
that a 21-step misses.

The main issues I've had with "plain vanilla" 21-step test strips can
usually be detected.  The first is that if there is a sharp turn in a ramp,
it is often a problem with a cross-over than can't be cured with
linearization.  You probably will not have this with ABW, as it uses Epson
cross-overs, which are generally outstanding.  Second, you're more likely to
get good deep shadow transitions if you have a compressed shadow region
going into the linearization.  That is, going in the black part of the curve
ought to look somewhat like -- but milder than -- gray gamma 2.2.  This
gives the program real information about what is going on down there, as
opposed to interpolated information.  In the extreme case, if there is a
sharp drop between 95% and 100%, you're asking for trouble.

Needless to say, to see these potential trouble areas I strongly recommend
graphing the pre-linearization results.  Linearization can easily handle
smooth curves, but sharp turns and kinks are trouble.  These are easy to see
when the pre-linearization curve is graphed.  The Spyder output text file
can be opened with Excel for graphing (inserting a line chart).

Paul
www.PaulRoark.com


[Non-text portions of this message have been removed]