I have an LG Plasma TV as part of my main HTPC setup. Although I calibrated it (and turned off things like dynamic contrast) when I first got it, I have always had an issue with the letterbox bars (bijv. on 2.4:1 ratio films) looking grey — i.e. being lighter than the darkest parts of the film. I googled to try to find a solution but was eventually convinced by repeated forums that it was just my perception and eventually gave up.
I recently rewatched Terminator 3 and during the intro sequence there is just white text displayed on a mainly black picture. There was no doubting this time that the letterbox bars quite clearly were lighter than the main picture — it was no trick of the eye. I again came back to google but still couldn’t find any solution. So I started playing around with settings. It turned out to be the simplest solution — I had the black level set to “high” rather than “low” on the TV settings. By default I tend to think of “high” as “good” but of course in the case of blacks “low” is actually what is desirable — this is a case of a confusing labelling of the setting!
So — to cure grey letterbox bars on your LG Plasma go to settings: picture: expert settings: black level and set it to “low”
“Hi James I realise it has been a long while, but I just checked this on windows 11 (build 23H2)…”