[Openicc] Drop size calibration

[Robert Krawitz]

   From: "Hal V. Engel" <hvengel at astound.net>
   Date: Mon, 28 Jan 2008 17:20:09 -0800

   On Monday 28 January 2008 16:31:46 Robert Krawitz wrote:

   > I'd be very interested in this.
   >
   > If you want to isolate issues of drop size vs. light ink, you can do
   > this:
   >
   > 1) Print normally at very high resolution (5760x1440 or higher), where
   >    only the smallest drop size is used.  2880x2880 or 5760x2880 may be
   >    even better due to the form factor, but on most printers those
   >    resolutions have problems near the bottom of the page.

   The targets I used were printed at 2880x2880 so it looks like this
   is probably light/dark ink transition rather than drop size
   related.  So are these higher resolutions only using the smallest
   dot size?  If that is the case does the dithering setting matter at
   these resolutions?

That would certainly be light/dark ink transition, not drop size.  The
fact that the yellow curve was smooth would tend to confirm that.  You
might still want to try the CMYK ink.

Ordered and Ordered New are identical if there's only one drop size.
There *should* be no difference between any of the algorithms (in
terms of ink coverage, at any rate) in this situation, but the error
diffusion and EvenTone algorithms won't print exactly the same drop
positions.

   > 2) Print at lower resolution using "4 color standard" (i. e. CMYK)
   >    ink.
   >
   > You can also print using CMYK at high resolution if you want a
   > baseline.
   >
   > I'm very interested in how Ordered New dither performs against
   > Ordered.  Ordered dither is just 2 levels, so it fills up one drop
   > size before starting to use the next.  Ordered New uses 3 levels, and
   > it starts a new drop size when the previous one is 50% in use.

   Gerhard asked me to do a target with more patches.  So I have just
   printed out a target with a 128 patch ramp for each channel but no
   CMY ramp since this was about all I could get on one page.  Once
   the target is dry I will measure it and post the results somewhere.

OK.  Again, no need to compare Ordered New against Ordered at this
resolution, but if you have a chance some time, I'd certainly be
interested at 1440x720 DPI comparison.

-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

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