HDR Reference White

In our blog post detailing the color correction workflow for HDR10, a reader asked where reference white and 18% gray should fall on the waveform monitor, and we incorrectly answered 100 nits for reference white and in the 40s for 18% gray. While typical white levels presently used in PQ production range anywhere from 145 – 250 nits, it is recommended that HDR Reference White (diffuse white) be 203 nits or 58% of the full PQ signal (input) level, as shown in the illustration below. Leaving little headroom (i.e. a higher value) means brighter diffuse whites at the expense of flatter looking specular highlights, while leaving more headroom allows for better looking highlights. It should be noted that 203 nits is only a recommendation for 1,000 nit peak brightness displays: that figure gets progressively higher for displays brighter than 1,000 nits.

If however, you’ve got graphics at 203 nits over a dark image, they may overpower the scene, whereas if the scene is very bright, the graphics may be difficult to see; larger areas of diffuse white may also appear brighter than a small area – which is why 203 nits is only a recommendation and not carved in stone!

“When creating text and graphics, it is important to prepare them for an HDR/PQ finish further downstream in the workflow as they can produce unexpected results. For example, white text/graphics created at code value 1023 (10bit) will appear as 100% white which is around 100 nits on a calibrated SDR display. This same text/graphic will again present itself at 100% white in PQ which would translate to 10,000 nits on a PQ display”. – Dolby

4 thoughts on “HDR Reference White

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  1. Thank you so much for your courteous response.
    ( I had asked you that question in your previous blogpost 🙂 )

    Looks like time for me to re-grade my BMPCC footage now.

    Also here is a small video I did in HDR – https://youtu.be/JnmbNSEOWgk

    It’s not super accurate… I just took all the old footage I had shot in BMPCC and Sony A6300 in RAW… and did simple Tone Mapping from BMD Film Gamma & Slog2 ( for Sony ) to HDR ST2084 spec ( I guess that’s why HDR PQ is… With Max Brightness set to 1000nit )

    Before shooting most of the Clips in the video above.. I used to take a small 2-3sec clip of Color Check Passport Video…

    So I guess I’ll try to re-adjust the clips based on the new Reference you provided for Diffused White and 18% Gray.

    Again Thanks.
    ( In one of clips in the video above…it’s my Nephew and my sister in a high dynamic range … I do see I am reaching the limits of the original BMPCC .. )

    1. Looks like you had fun playing around with all that footage! I like the backlighting in the shot of your sister holding your nephew. 203 nits is the official number for HDR Reference White, which is why I shared a link to a paper in the blog post arguing why 200 nits should be the standard. But that’s nitpicking! 😂

  2. Also, I am using LG CX OLED as a reference monitor.

    I override the HDMI Signal using their secret ( not a secret anymore ) menu – 1113111

    I set the Gamma to HDR ST2084 , Color to Rec 2020 and Mastering to 1000nits..

    Hope what I am doing this correct..in terms of setting up the TV for mastering…

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