Luminance error

Anything and everything to do with DCP-o-matic.
DCP-Junkie
Posts: 20
Joined: Mon Feb 17, 2020 9:43 pm

Luminance error

Post by DCP-Junkie »

Hi,

I am getting an error from the theater and I don't understand it. Can you help me with this? I have built a number of DCP's now that with this software and I don't remember ever having to set a luminance level. I did find the setting but it was unchecked by default. How do I know what to set that luminance at? The default looks like it is 0.1 as a default and I found one article referencing that setting but I found another saying it should be set to 14. How do I know what it should be on the different films that I work on? Here is the info from the theater on the error:

Thank you in advance for your help.

Error - cpl=************************************; Luminance element is missingDescription
The Luminance element shall be present. The value indicates the screen luminance at which the content was authored.
Remediation
Create a new CPL, including the Luminance element and settings its value to indicate the luminance the picture was authored, and which should be viewed at.
carl
Site Admin
Posts: 2548
Joined: Thu Nov 14, 2013 2:53 pm

Re: Luminance error

Post by carl »

As far as I can see the luminance metadata is optional, so it's strange that the theater are complaining about it being absent.

I would suggest clicking on "Metadata...", going to the "Advanced" tab, ticking the "Luminance" checkbox and setting it to 14. Then re-make the DCP.
Carsten
Posts: 2804
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Luminance error

Post by Carsten »

I don't know any server that would complain about a missing luminance value. That means, they may employ a separate QC tool before they ingest your content on the server. Originally, the luminance value was only meant for 3D DCPs, as the target luminance for 2D is always 14fL, and there is some variance allowed for 3D target luminance. I ingest content for more than 10 years now on all existing servers, and the ISDCF/metadata luminance value NEVER played a role. Also I never heard about problems with it on any other forum. 3D Target luminance is sometimes discussed for specific installations or releases (e.g. AVATAR 2 was released in different 3D target luminances).

What type of cinema is this? Plain vanilla, or IMAX, Dolby Cinema?

Honestly, I think someone is making something up here. For what reason ever...
StephW999
Posts: 43
Joined: Mon May 17, 2021 1:15 pm

Re: Luminance error

Post by StephW999 »

carl wrote: Wed Apr 12, 2023 9:59 am As far as I can see the luminance metadata is optional, so it's strange that the theater are complaining about it being absent.
+1
and I agree with you Cartsen
DCP-Junkie
Posts: 20
Joined: Mon Feb 17, 2020 9:43 pm

Re: Luminance error

Post by DCP-Junkie »

Thank you all for your input. I just remade it and it added it to the title of the DCP so I guess that will work. It is a Dolby Cinema.
Carsten
Posts: 2804
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Luminance error

Post by Carsten »

Dolby cinema uses a proprietary HDR standard that is able to achieve higher peak luminance. In order to adjust their system for standard viewing parameters, they may have to rely on the luminance value being present.
Hvy1955chvy
Posts: 1
Joined: Thu Jul 11, 2024 3:04 pm

Re: Luminance error

Post by Hvy1955chvy »

Carsten wrote: Wed Apr 12, 2023 8:23 pm Dolby cinema uses a proprietary HDR standard that is able to achieve higher peak luminance. In order to adjust their system for standard viewing parameters, they may have to rely on the luminance value being present.
With the rise in high output and contrast laser light sources I am seeing more EDR/HDR options in cinema systems. For instance Barco's 300nit Lightsteering projetcor look very interesting.

I for one would like to see a PQ related translation settings in future releases. The great thing about 'o-matic is making non cinema content appropriate for cinema display in native cinema media formats. With cinema projectors having new attributes like greater dynamic ranges, HDR EOTF and greater than P3 Gamuts, it would be great to be able to have settings that help us utilize them :D