Doug,
On one of your previous posts you referred to a stagger pattern but did not define. I want to gain insight into which tracked stagger geometries are best, i.e. fewest neutral and near-neutral patches that result in "satisfactory" accuracy. So what is the geometry you're using for your latest results?
Richard Southworth
For device neutrals, step from 0 to 255 in 15 increments. For each step add additional triplets where each channel is increased by 15. For instance:
0,0,0, 15,0,0 0,15,0 0,0,15 15,15,15 30,15,15 15,30,15 15,15,30, ...
Theory is similar to your 120 degree ab rotation. Increase in red channel is less cyan, green is less magenta, and so forth.
This works well with a small, but significant population of color patches. For that test I used 91 which is a 4x4x4 with an interspersed 3x3x3 set.
For the tracked sets, I started with L* every 3 units. Converted to RGB using either Rel. Col or Abs Col. Then added a smaller stagger value of 5 instead of 15 since the RGB set has already been mapped to very near the desired positions.
These are, however, the first tests I've done with simultaneous Rel Col and Abs Col on a single print run which eliminates subtle effects from the printer such as the occasional "cartridge agitation."
Added: Probably worth noting that every print is measured forwards and backwards, then the results are compared and averaged. This reduces spectro variations and also provides a mechanism to detect anomalous readings from dust contamination of low L* patches.