That's a clue they are overcompressing and in a small screen the 1080i (vs. 1080p) likely will look fine.
Reading http://www.dslreports.com/forum/r30287660-CATV-How-do-you-get-1080-res you might want to ask how to test it on 720P and see if the TV's upscaling is better than Charter's 1080i.
Good Morning,
I recently bought a 55 inch LG OLED tv. The picture it shows when playing movies, video games, Netflix, etc., is incredible. However, when I watch cable (I have Charter), the picture isn't as good at all. I called LG and they told me to get a better cable box. I called Charter and they told me that there wasn't a better box than the 1080i HDTV box they gave me.
The weird thing is, when I hit the All Inputs button on my tv and it shows me the smaller screen preview of whatever input I have the tv on, the picture looks awesome. Only in full screen mode is it not as good.
I'm not a tech guy, but am I missing something blatant here? Any insight would be appreciated.
Best,
Ed

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