dci white point

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qqqavi
Posts: 1
Joined: Tue Apr 14, 2020 5:47 pm

dci white point

Post by qqqavi »

Hi everyone,

I'm new to this forum, also new to dcpomatic and new to dcp in general. I apologize if this has been asked before but I can't find an answer. :oops:

I'm confused about the difference between white points. For example, I've just discovered that there's no such a thing as D63 white point for DCI, it is not even a D illuminant and this greenish wp is pretty much obsolete from the time when "projector manufacturers were concerned about achieving maximum brightness at 14fL for colors on the daylight axis". This makes sense to me.

Therefore, as I understand todays new projectors can render up to 52.37 nits max. luminance in order to acommodate several white points (D60, D65, D55). That means a projector should be able to reproduce whatever white point comes with the XYZ "flavour". If your source is Rec709 and D65, the wp of the projector should be that as well.
Is this accurate?

I know D65 is more for broadcast but why DCI Thetrical is actually D60? In one publications they say D60 for theatrical is controversial.Can you
recommend a situation when using D55 or D60 and why?

Thank you.

Carsten
Posts: 1600
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: dci white point

Post by Carsten »

The only thing I ever read about this was that 'DCI allows arbitrary whitepoints to accomodate any need'. However, what I know from theatrical, this seems to be a grading only decision, as theatre equipment is calibrated to only one white point and stays there forever, and there is nothing in a DCP that sets or shifts a specific whitepoint (other than the content inband itself).
So you may work with a custom whitepoint during grading that has to fit within the theatrical gamut. That's how I understand it.

- Carsten

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