I wanted to compare the meter correction technique that HCFR uses (RGBW 4-color matrix solution) to what ArgyllCMS is doing to evaluate any differences. The data below was obtained via the following:
1. Profile a D3 against the JETI-1211 using ArgyllCMS
2. Measure a test set with the JETI-1211 and the profiled D3
3. Profile a D3 against the JETI-1211 using HCFR
4. Measure the test set again with the HCFR profiled D3
5. Remeasure with the JETI-1211 for repeatability
In Step 1 ArgyllCMS calculates the best-fit matrix that minimizes color difference errors between the two probes (as opposed to the closed form solution of the 4-color matrix method). For this method I used a profiling set of 22 colors consisting of 25% increments along each color axis and ~11% increments along the neutral axis.
Steps 2-5 use a different set of 37 test colors at higher density along each RGBW axis.
Steps 3 and 4 were repeated using both 100% RGBW and 75% RGBW patches to form the HCFR correction matrix.
Results show that the ArgyllCMS method reproduces the reference values somewhat better than the 4-color method and the 75% level-based a tad better than the 100%, although the absolute color differences are pretty small (mean dE2000: best-fit =0.19, 75% 4-color=0.26, and 100% 4-color=0.39). Repeatability was excellent at 0.09 dE2000 mean difference.