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Re: HDR in the real world

Re: HDR in the real world


David Rasberry
 

Refinements to grading standards and the HDR firmware in consumer displays that interprets those are certainly welcome. But it does not relieve the necessity of doing at least a basic value scale calibration of the TV to one's own viewing environment. Value distribution in programs, especially through the critical midrange , shouldn't shift dramatically between SDR and HDR material. Most of the desired value differences show in extending the contrast range at the extremes maintaining color, texture and detail into deeper shadows and more subtle shading differences in near whites as well as better micro contrast and color contrast. 

I bought a new 65" mid-range LG HDR   LED TV for the living room last winter in anticipation of the Covid lockdown.  It is a typical 300 +/- nit display, not the 1000 -1500 nit range of the high end models.  It supports HDR10 and HLG standards but not Dolby.  The native black level of the panel is perhaps two stops lighter than the inky blacks of a high end OLED set but it is far superior to the 15 year old 32" LG it replaces and amazingly cost the same price as I paid for the old one.
It sits in a dark corner of the room on a 42" high book case to the left of a large picture window that occupies half the wall space.  This morning is overcast with outside ambient light levels running about 160-200 FC  and the light coming through the window measuring about half that.  Two couch side reading lamps are on across the room.  Ambient light at the screen surface measures 5+/- FC, which I would say is typical for morning and evening viewing conditions.  It can go as high as 15 FC mid afternoon on a bright sunny day.

I like LG's because they have  easily accessible Expert mode user calibration menus and a built in guided visual calibration routine for basic brightness, contrast ,sharpness, color, and gamma tweaks that works pretty well.  The new HDR set added two Expert mode user presets, one for dark room and one for light room conditions. Menu access to the HDR modes was a bit quirky on the new set as one actually has to be viewing HDR material to access them.  Initial out of the box viewing experience with HDR programs on the new set was disappointing as Geoff describes, with very dark average scene values and muddy shadows on many programs regardless of which standard viewing mode was selected. The basic guided calibrations didn't help this.

I found this test chart online to use for a visual reference: Test chart


It maps full data range gray scale values as well as the usual REC709 value range.  Ran the chart through Resolve to check and correct it by the scopes and exported a 10bit HLG REC709 conversion to use as a reference for visual calibration.  I set HDR black levels, brightness, gamma and contrast to match room viewing conditions and resolve the full data range gray scale values.  An important HDR menu adjustment is one that acts like a dynamic range expander to push the maximum range the display is capable of accurately reproducing between panel black level and white clip.
Even with this approach it took several rounds over a few days of viewing to get it dialed in to my satisfaction, but now most HDR programming map values as it should and the shifts in DR, grayscale, color refinement, and micro contrast really pop the HDR material compared to SDR without radical and inappropriate value shifts viewing anything from live newscasts to Neflix Ultra HDR streams. 

Mind you there are still a lot of poorly graded muddy dark program examples out there, but many that look spectacular too.  It is even possible to distinguish subtle differences in qualities between digital and film originated material. Some of the recent HDR restorations of films like Coppola's Cotton Club are lovely.

Worth giving it  a try.

David Rasberry 




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