Hi Garry,
Your comment is much appreciated.
Let me explain my standpoint a bit, look at some real data from traditional sensors:
These are probably from a DALSA sensor (o-marks), Canon 5dIII (dashed) and a Kodak sensor straight.
Now, Doug shows these curves as typical of traditional CFA designs:
The curves Doug presents as traditional approach lack scales, but we can still see some characteristics that are clearly absent in the real world data:
- The peak in the red channel is missing in real world data.
- Crossover between red and blue is pretty high
- The slope of the red channels on the left is very wide
- The green and blue curves have high values on the right side of the graph. In real world data they are zero.
So the curves shown as traditional are very dissimilar from real world curves. Would Doug say that the traditional curve was "Hasselblad", Hasselblad would certainly become very much upset. The curves also contain features not existing in real data, that actually makes them fake, they don't simplify but they do misspresent.
The left flank on the red channel is typically very steep. The right side the IR-filter sets in. It could be that Doug presented a curve without IR filter going well into the near infrared, but sensors have IR filters. Sometimes a bit to weak, like on the Nikon D200 and the Leica M8, I would recall.
Sony sensors seem to have a red channel response between between P1 (DALSA?) and H2D (Kodak?).
Canon sensors differ a bit in that crossover of blue and red are not at zero, but the cross over is still far below Doug's illustration:
So, what about the Thrichromatic? Doug here shows a diagram that is much closer to real world traditional sensors than the traditional sensor.
Now, do you think that the image on the left is closer to traditional CFA response than the illustration at the right?
So what Doug says is that traditional sensor response is very different to reality. Than he uses a diagram that is pretty close to traditional sensor design to say that it is better design. In engineering where I come from you are not allowed to do such things and in science definitively not.
Now, it my not be Doug's fault, he almost certainly got the illustrations from Phase One.
Later in the article, Doug states that the Thrichromatic probably does not benefit the Cultural Heritage work, as it is numerically driven field. This could indeed be the case. Quite possible that the Cultural Heritage work has better controlled lighting conditons.
Still, he indicates that some problematic colours, like Cobolt Blue may reproduce better colour. I have checked a bit on Cobolt Blue and it has an interesting reflection spectrum, intensive in blue, but lacking greens and reds but having very high intensity in IR. Could it be that Thrichromat has a steeper IR filter than older Phase One backs?
Best regards
Erik
Erik.
There's a difference between 'fake' and simplified information. Fake implies 'deliberately misleading'. Doug's article was targeted to an audience with a certain level of technical understanding and his simplified graphs were easy to get the gist of.
In my opinion, you have been a bit of an insulting dick towards Doug, who has responded graciously with his enquiry as to your wellbeing.
A well written article by the way Doug.
Garry