I have a 37" Insignia LCD HDTV. It is capable of 1080p. When I play Call of Duty 4 on my PS3, which has the capability of playing in 1080p, my TV puts itself automatically on 1280x720. I've tried going on the menu of the TV to change the ratio, but couldn't find an option to do that. Does anyone know if there is a way to manually change the ratio of the picture so that Call of Duty will be in 1080p?

HDTVs always operate their panel at their native resolution of 768p or 1080p. The input resolution, if supported, is scaled/deinterlaced by the video processor to the native progressive resolution of the panel. This is done automatically by the set. The only variable is the HDMI inputs which have two-way communication with the source (PS3, DVD player, STB). The source resolution is set to match the set by this handshake.
I assume your Insignia is a NS-LCD37HD-09 or equivalent 1080p set. They also make a 768x1366 set. I researched the NS-LCD37HD-09 and could not find a manual or any review which provided its input resolution. Some 1080p sets do not support 1080p though they all support 1080i and 720p. My 2006 1080p JVC does not support 1080p inputs. Does the manual show the set supports 1080p resolution on its component or HDMI inputs? I understand that few sets which support 1080p do so over their component inputs. I also assume you have the PS3 set for 1080p and connected over HDMI. If your set doesn't support 1080p resolution I would have expected the HDMI handshake cause the PS3 to fall back to 1080i. Have you tried a DVD on the PS3 to see if the set supports 1080i or 1080p in that mode?

If my set doesn't support 1080p, does that mean that it doesn't support 1080i? Because I couldn't find any info on the TV's resolution capabilities in the manual, on the box, or ports either.

Your set can accept a 1080i signal, it just gets converted by the set for display to whatever the fixed resolution of it's panel is. What model TV do you have?

If my set doesn't support 1080p, does that mean that it doesn't support 1080i? Because I couldn't find any info on the TV's resolution capabilities in the manual, on the box, or ports either.

As I stated above all 768p and 1080p sets support 720p and 1080i. There are no exceptions. They support those resolutions on both component and HDMI inputs. Composite and S-Video inputs only support 408i, not even 480p.

Yeah I can't figure out what's going on. The TV is on 1080p when I'm at the main menu on my PS3, so I know that the TV is capable. But then when I start Call of Duty 4 which supports 720p and 1080i/p, it switches back to 720. Could it have anything to do with my HDMI cable? It's a Radio Shack brand $100 cable that goes directly from my PS3 into the TV.

You might try posting this in the Blu-ray Player forum which is the location for the PS3.
http://www.avsforum.com/avs-vb/forumdisplay.php?f=149

It is unlikely the HDMI cable is at fault.

I'd take the cable back also, you got ripped off...

Yeah I can't figure out what's going on. The TV is on 1080p when I'm at the main menu on my PS3, so I know that the TV is capable. But then when I start Call of Duty 4 which supports 720p and 1080i/p, it switches back to 720. Could it have anything to do with my HDMI cable? It's a Radio Shack brand $100 cable that goes directly from my PS3 into the TV.

COD4 is natively 720p, so therefore it will play in 720p. If you want to force it in 1080p, just go into your display settings on your PS3 and uncheck 720p, and 1080i, leaving only 1080p checked.

Trust me though, there is no difference whatsoever in the PQ between 720p and 1080p on COD4. You are best off leaving it on 720p.

Yeah, I still couldn't figure out how to change it. I just wanted to see how much better the game looks in 1080p..but I'll forget about it and take skeelo's word for it. Thanks for the help anyways guys.