Interesting posts Edmund, though I am not sure I understand what you mean by 'green discrimination' and I don't have anything to compare your negatives to. Can you explain a bit more, a bit more quantitatively? Do you mean that the color filters are less selective than in other sensors in order to gain a little extra sensitivity? If so that should be easy enough to quantify for people like Jim Kasson.
Jack
Jack,
I think the simple quantitative stuff which interests you is all here.
http://www.dxomark.com/About/In-depth-measurements/Measurements/Color-sensitivityAs for "easy to quantify", things are not so simple. Color like sound is a percept. So one's quantification always relies on judgements. This is why there are "color consultants", who look at stuff and bridge the quantitative and the aesthetic. In fact there is a "color community" and people hold meetings and commission studies to figure out what metrics to use, and how to measure them, and what sort of values are acceptable. Then the various firms like DxO, Imatest and Image Engineering implement those metrics, as they are written into some standard.
For instance, a year or so ago I happened to be at a phone-camera quality meeting in Paris, physically hosted with great generosity by DxO, and at one people were discussing image noise. Somebody had commissioned a first study, and it seemed to demonstrate that consumers who now view everything on a screen prefer images with chroma noise to luma noise.
This seemed counterintuitive to just about every person in the room, because as you know we photographers hate chroma noise, and so a second study had been undertaken, and it had confirmed those results.
And so in the future, cellphone camera designs (and probably consumer and then pro cameras) will be optimised to prioritise filtering luma noise when possible, over chroma noise which consumers appear to tolerate better, although old-gen experts hate it.
I'm not a particular expert on anything, but as you know I used to be an ICC member and so I know the process. Andrew Rodney, a color consultant who used to be a regular on these forums was also an ICC member, way back. A lot of the color geeks in companies and and the color consultants and image consultants sort of know each other, have corresponded with each other etc.
Digital color is very much a collaborative process as images are captured under some commercial illuminant manufactured to standards issued by the CIE, move to a raw file, are converted to a colorimetric space defined by the ICC, get displayed on a monitor that needs to be calibrated and also placed in acceptable working viewing conditions in which a retoucher can work and then printed using profile formats and conversions described by the ICC. We move all the way from real-life spectral color in an on-site perceptual context, all the way to viewing a flat reflective print. Across these steps, there is a basically a collective assessment of color in which the whole community continually participates, as measurement methods, color conversion algorithms and assessment criteria get accepted across the industry and rolled out so that each device can talk to the next, and the consumer sees an image that reminds her of the dress she wore on her sister's wedding day.
Edmund
PS. I still stand by my personal and subjective opinion that the A7RII is not very good at discriminating greens
