[Openicc] Drop size calibration

[Hal V. Engel]

On Monday 28 January 2008 14:31:45 Gerhard Fuernkranz wrote:
> Hal V. Engel wrote:
> > I suspect that drop size calibration has a lot in common with calibrating
> > the light/dark ink transitions in CcMmYKk type printers.
>
> Btw: This statement, which brings drop sizes and light/dark transitions
> into relation, reminds me on another approach I have seen somewhere in
> the literature. This approach does the dark/light splitting in the
> dithering engine: It treats the e.g. 16 dot-on-dot overprint
> combinations of the three dot sizes of "C" and the three dot sizes of
> "c" as if they were 15 drop sizes of a single virtual cyan channel. Then
> these 15 virtual drop sizes are sorted by density, and dithering is done
> between the resulting 16 virtual levels. A requirement for this approach
> is of course that the hues of the dark and light inks must match
> sufficiently well, i.e. the dark inks should be basically the same
> colorant as the light ones, but at a higher concentration. I have no
> idea though, how well this approach works in practice...
>
> > It is posted here:
> > http://lprof.sourceforge.net/images/Channel-Error.jpg
>
> Do you still have the tabulated measurements too?
>
> Regards,
> Gerhard

I could recreate these without too much trouble.  I improved the spreadsheet 
since I created that graphic and it now graphs the K channel.  I could simply 
print out a new target with the GutenPrint default settings and re-measure it 
and drop those measurements into the spread sheet.  I could post the 
spreadsheet where people could have a closer look since this would have the 
graphs and the measurement data.  In addition others could use the spread 
sheet to plot other things, for example, how the hue of a channel changes 
with density.  I could have this available tommow (to allow for drying before 
measurement) if anyone is interested.  It only takes about 5 minutes to 
measure a target and about one minute to get the measurements into the 
spreadsheet once the target is ready to measure.

Hal