Is HDR limited to 4K content or is it device dependent?
Having recently purchased a HDR 4K TV I have noticed that only 2160p content activates the HDR settings and on screen icon.
1080p and 720p content encoded with 10bit colour depth do not display in HDR
. Is this correct.
720p and 1080p are also Ultra HD resolutions and so can offer HDR, Star Trek Discovery being an example. If the content is meant for TV and it's 10-bit, it's HDR*. What is it you're trying to view that's not triggering your TV's HDR mode?
*To be clear, 10-bit doesn't equal HDR, it's just a part of what constitutes an HDR signal - SDR signals are 8-bit.