When the DCI (Digital Cinema Initiatives), a joint venture of Disney, Paramount, Sony Pictures Entertainment, Universal and Warner Bros. Studios, published its recommendations for next-gen HDR theatrical presentation in High Dynamic Range D-Cinema Addendum Version 1.0, a black level of 0.005 cd/m2 and peak brightness of 300 cd/m2, for an overall contrast ratio of 60000:1, were settled on. Interestingly, P3-D65 (or 6500K, as compared with 6300K, the white point of D-Cinema SDR) is specified as the color volume rather than Rec.2020. The question is, why? The DCI explains that firstly, only a specific class of commercial projectors is capable of approaching BT.2020, i.e. RGB laser projectors, while LED displays even struggle with DCI-P3 and the D-Cinema HDR standard was developed to be agnostic to the specific type of imaging device. The DCI continues,
“Lastly, DCI had to weigh the creative value of BT.2020. We’ve worked closely with colorists in attempts to demonstrate the value of colors outside of DCI-P3, and those attempts have been far from compelling. In general, colorists prefer to reduce color saturation. This isn’t entirely without exception, of course, as there have been some notable examples of studios utilizing color values far outside of DCI-P3 but they’re extremely limited. For example, Pixar, in a single shot in the movie “Inside Out”, notably opted for a green value well outside of DCI-P3 to depict broccoli. Nonetheless it’s been difficult to make a compelling case for the real creative value there. So, given all the challenges to achieve 100% BT.2020, the lack of any standard that describes a realistic subset of BT.2020, and the doubtful creative value, DCI opted to retain DCI-P3 as the color gamut for the D-Cinema HDR specification/standard.”
In fact, the clip from Inside Out was eventually excluded as an anomaly from the DCI’s HDR Double-Blind Image test:
“[T]he introductory scene from “Inside Out”, with the birth of the character – opens with a longer period of complete darkness followed by full brightness across the entire frame. The intended creative purpose for this is to make viewers very uncomfortable, matching the experience of birth. While this desired purpose was successful in making the testing participants uncomfortable, it resulted in very inconsistent ratings and therefore has been excluded from these test results.”
The Daejeon Chronicles 
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