So there's something I really don't understand at all in the "calibration report" images provided in TFT Central reviews. This one from the Dell U3014 review
is a very good example:
The issue I have with this report is that, the way I understand the basic principle behind DeltaE, it really doesn't make any sense to me. Let me explain. DeltaE is the perceived difference between two colors. So, as I understand it, when we say that a measured color has a DeltaE of 3 (for example), it means the perceived difference between the measured color and the reference color
However, before we make this comparison, we must agree on a well-defined reference. For example, in the right part of the report, I'm assuming that the green bar is the RGB triplet (0, 255, 0). Which, for sRGB primaries, means (0.3,0.6,0.7153) in xyY coordinates. So, assuming I'm right so far, the green bar is the deltaE between the reference sRGB green primary (xyY 0.3,0.6,0.7153) and the actual measured color for the green primary (RGB 0, 255, 0).
Now here is where I get really confused by the report: according to the gamut on the left part, the measured green primary (top corner of the black triangle) is completely off the sRGB primary (orange triangle). Indeed, the measured green is way too much saturated. This means that the DeltaE for the green primary should be huge (at least 10, probably much more). Yet according to the right part, the green primary has a DeltaE happily sitting around 0.1 or so!
Again: the left part (gamut) tells us that the green primary is grossly oversatured with regard to the reference (sRGB). The right part (bars) tells us that green is just fine with a DeltaE of 0.1. So which is it? Is green completely off or is it spot on? This looks completely inconsistent to me.
The only way I can explain this is that the DeltaE bar on the right part of the image is not calculated with respect to sRGB, but to some other reference. In which case I would very much like to know what this reference is.
I'm asking this question because I recently acquired two Dell U3014s and a i1 Display Pro colorimeter. However, I've been unable to reproduce the results in the review for these two monitors. The review is showing near-perfect results with the sRGB factory calibrated mode and hardware calibration, with insanely low DeltaE values (average well below 1.0). The results I got with my brand new colorimeter and the HCFR Calibration software are much more pessimistic, with e.g. DeltaE between 5 and 9 for the primaries, even after the hardware calibration procedure. I'm desperately trying to understand why my results are much worse than what they should be, and while trying to compare the numbers I got with the calibration reports in the review, I realize that I'm unable to interpret any of them because, according to my understanding of DeltaE, they don't make any sense.
Can anyone help me share some light on this?