Digital BW, The Print

>Small question for QTR curve design experts...
>
>I'm starting to get some very good results now out of QTR (on a 1280
>with UT2 inks), but am a bit stuck on one issue: the density difference
>between 100% black and 99% black is much too large, so that, if an image
>contains a large area of 100% and an adjacent area of 99%, the edge
>between them is clearly visible and the 99% region looks dark gray
>rather than nearly black.

I'm not an expert yet, but ...

The step you're seeing is probably the difference between LIMIT_K and 
BOOST_K. LIMIT_K controls the linear-ish region of black ink usage, 
and BOOST_K controls only maximum black.

Reduce BOOST_K and the step will be more subtle, but you will pay in 
reduced Dmax.

Increase LIMIT_K and (assuming it was right in the first place) you 
may lose some of the differentiation between 99%, 98%, 97% etc. In 
this case you'll also need to re-linearize, and you may also need to 
adjust the GRAY_VAL numbers (ink partitioning).

Which is preferable may depend on your style. If you make images with 
large areas of maximum black, you won't want to compromise Dmax. If 
you don't, you probably care more about shadow differentiation.

In an ideal world, you wouldn't need BOOST_K at all, and everything 
would be smooth.

The above is based more on my understanding of the theory than on a 
lot of practical experience, so I'm open to being corrected by 
somebody who knows better.

   -Paul
kb5mu@...