Hello everyone,
I'm attempting to create CMYK profiles for an HP Indigo digital press. This
particular unit is not well maintained and after a series of experiments,
I've determined that the K ink is a constant source of banding and also
visible graininess due to poor dot formation.
Thus I've been trying to build black ink curves which minimally introduces
black, which means telling Argyll to make the curve shape concave (<1.0),
with a command such as this:
-kp 0 0.33 0.95 1 0.5
I've noticed that doing more severe concave curves tends to result in a
kink at the black end point. This kink is always at the 90% point. Here is
a link to the screenshot of the curve preview generated by xicclu.
https://drive.google.com/file/d/1UE-DaCallwUTQjVS-1qrV53NEyM3TuTa/view?usp=sharing
Interestingly, the white end of the curve never develops any kinks
regardless of the stle and stpo value for any shape parameter between 0.0
and 2.0. It only and always affects the black end.
When reducing the concave-ness of the shape to ~0.8, the kink is virtually
gone. Perhaps this curve's spline turning point is hardcoded and I'm
wondering whether it might be possible to get a smooth gradual transition
to dmax whilst enforcing a more concave shape. Thank you!
Regards,
Samuel
