If you’re lucky enough to have pre-ordered an LG C3 OLED or LG G3 OLED from LG before their wider roll-out to stores like Best Buy and Amazon, make sure you download the latest firmware update, as it’s going to completely change the way you see your new TV.
The firmware update version 03.01.19 changes the auto-dimming feature so that darker scenes with little action don’t slowly become darker over time.
The issue and the fix were discovered by HDTVTest’s Vincent Teoh who bought the LG 42C3 and LG 65G3 with his own money and found that there was no way to adjust the "Temporal Peak Luminance Control" (TPC) in the manufacturer settings.
Without being able to turn that feature off, the TV’s auto-dimming algorithm kicked in any time there were “prolonged, dark HDR scenes”, making them unwatchable after a few minutes.
The fix, available via over-the-air update, changes the way the TPC works and won’t kick on the auto-dimming feature when it plays dimmer content.
Why does LG C3 have auto-dimming in the first place?
Auto-dimming has been a feature for a few years now, but it’s really come into its own thanks to the rise of Dolby Vision IQ that can adjust the brightness of the image depending on how much ambient light there is in the room.
The thinking here is that, if you’re in a bright room you might need your content to be a bit brighter so that you can still see all the details. If you’re in a darker room, the screen dims itself so that you’re getting the most optimum performance.
The issue that LG’s OLED TVs faced looks like a feedback loop with the ambient light sensor. The TV was in a dark room so it dimmed the picture, but then the dimmed picture produced less light for the ambient sensor to pick up on. This created a negative feedback loop where the picture just became progressively darker.
There are ways to turn off the auto-dimming feature — and, by extension, Dolby Vision IQ — entirely. But LG's fix will help folks who want the convenience of auto-dimming and still, you know, be able to see the picture on the TV that they paid $2,000 for.