HDR Graphics White nits value changes my video levels

[digitlman]

Everything and everyone says this setting is only supposed to be for Graphics, however changing the value then changes the video levels in my monitor, on the scopes, and on my Blackmagic Decklink output.

https://youtu.be/meafmMwLAZg

Here is an example video,

I spoke with Matt Christensen in the Adobe booth at NAB and he indicated this should not be happening. This is my video proof.

Is there some setting or something i need to change that is causing this?

thanks

[Francis-Crossman]

HDR graphics white can be a very confusing parameter.  Despite the name, it has no control over graphics.  It controls the scaling of video levels when converting between color spaces.  The nit value (100, 203, 300) refers to how bright a white card should be in an HDR scene.  Imagine putting Rec709 into an HDR sequence. In the Rec709 scene, you are shooting a white card, and it's exposed all the way to 100% IRE (100 nits). PPro will automatically do a colorspace conversion, but we need to know how bright the result should be.   Graphics white says to scale the values such that the white card lands at 203 nits in the HDR sequence (or 100, 300).  203 is generally the industry standard.  203 is 75% of the signal in HLG.  You wouldn't want to scale 100% in Rec709 to 100% in the HDR scene because it would be far too bright.  The setting gets its name from the industry recommendation that pure white graphics like subtitles or end credits should land at a specific nit value - generally 203.  But our graphics tools are not affected by this value.  It's up to you to set the level properly for graphics.

There is a lot more detail here: adobe.ly/hdr

[digitlman]

Thank you for your detailed response, And thank you VERY MUCH for the pdf guide. I had seen something similar in the past online, but this document is far more elaborate!

[Francis-Crossman]

happy to help @digitlman !