[Openicc] Drop size calibration

[Gerhard Fuernkranz]

Graeme Gill wrote:
> Right, yes you need to be able to mix three drop sizes to avoid
> banding issues as the screen gets close to 100% of one dot size
> (which was what I meant by overlap of different dot sizes).

But if we close down the first first drop size before reaching 100% area
coverage, this implies that the next drop size should basically start
dithering into the "holes" which have not yet been filled with the
previous drop size, in order to obtain the least visible dot pattern.
Wouldn't this - in the optimal case - require a threshold array for the
2nd level which is particularly tailored to the ink limit of the first
level? Or do you think, it does not matter?

> Sufficient overlap should smooth some of the worst of this out,
> since it's the near 100% fill that has the highest dot gain,

Isn't the "dot gain" (i.e. effective area coverage (computed from
measured densities) minus prescribed area coverage (in %)) zero by
definition, at 0% and 100% fill, and has its maximum rather somewhere in
the middle?

Regards,
Gerhard