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1080i vs. 720p question (1 Viewer)

Kris K

Auditioning
Joined
Jun 24, 2004
Messages
3
HI all,

I am a new subscriber to this forum, but have been reading it for some time. I have found the HDTV threads very interesting, but there is a question that I have regarding the two formats and their transmission.

I recently purchased a 50" LCD projection hdtv that is capable of displaying both 1080i and 720p. I prefer 720p, so I have the converter box set to transmit to the tv in 720p. However, I cannot tell what hdtv format is being transmitted to me (it may be 1080i or 720p). Since my converter box is set to 720p, if you query the tv as to what signal it is receiving it says 720p. Also, as you would expect, if you change the converter to 1080i, the tv then responds that is displaying in 1080i.

My question is, let's say that the incoming transmission is in 1080i and I have the converter set at 720p, what is the converter doing to convert the picture to 720p, and is there a positive or detrimental effect in viewing quality to do that? I guess what I'm asking is, if I am receiving a 1080i signal, should I set the converter to transmit native 1080i to the tv, or is it better to set the tv to the format that I prefer (720p), or does it really matter?

Thanks and regards,

Kris K.:)
 

Michael TLV

THX Video Instructor/Calibrator
Senior HTF Member
Joined
Mar 16, 2000
Messages
2,909
Location
Calgary, Alberta
Real Name
Michael Chen
Greetings

You need to determine if the TV does a better job of conversion than the STB. Without seeing your set up, no one can help you on that except yourself.

Regards
 

Jeff W.

Stunt Coordinator
Joined
Dec 21, 2003
Messages
141
Everything will be downconverted to 720 anyway, since that is the maximum resolution of your LCD.
 

Kris K

Auditioning
Joined
Jun 24, 2004
Messages
3
Jeff W,

What do you mean everything is downconverted to 720p? According to my manual, 720p is displayed as 1290x720 and 1080i is displayed as 1920x1080. Is that not the correct resolution for each of those formats?
 

Jonathan Dagmar

Supporting Actor
Joined
Dec 29, 2002
Messages
723
You must be misinterpretting what your manula is saying. LCD's, unlike CRTs, have a fixed resolution, currently almost universally 1290X720, which is conveiently the same resolution as 720p. that means that all 1080i signals will be converted to the native resolution of your LCD projo before being displayed.
 

Kris K

Auditioning
Joined
Jun 24, 2004
Messages
3
Jonathan,

Thanks for your reply. I am still learning about all of this, but when you say an LCD has a fixed resolution, you have to be right. You can't change a fixed number of pixels. I guess I just never thought about it. Maybe my manual refers strictly to input signal, and not what is being displayed.

I really like the TV, and I prefer 720p anyway, so it's really of no consequence to me. I guess that explains why, no matter how hard I tried, I couldn't tell the difference between 720p and 1080i. :laugh:

Thanks,

Kris K
 

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