HDTV signal handling

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gofar99

gofar99

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Joined 2007
oddwattaudio.com
#1
Greetings everyone, I usually stick to other diy fields but encountered a question for which I couldn't find a definitive answer. It didn't seem to be covered in the "search", but I may have missed it. The question relates to how HDTVs handle some inputs. Specifically, what does a LCD HDTV do with a signal that is not at its native resolution. I suspect that various brands may differ but I'm looking for a sort of general answer. Suppose you feed a 1080i signal to a 720p TV (via cable, sat etc). What it is likely to do? Do LCD HDTVs act like computer monitors in this instance and come up with a usable image or what? If there is a good link or previous answer on the subject I would appreciate the info.

Thanks
gofar99
 
#2
Well they can do a few things, each with varying grades of quality (usually price comes with quality). Most just scale the image, either by dropping pixels (mostly on VERY cheap models) or summing up pixels (think of it as, ok i need to show 3 pixels in the space of one pixel. what is the average color between these three? Now set this display pixel to that color). Some of the upper brands have complex algorithms that can incorporate ALOT of difference technique such as anti-aliasing and color management. So either way you will be losing quality. Now this even goes with trying to display a 720p video on a 1024x768 monitor. It still has to run algorithms to make up for the difference in number of pixels, now the difference it VERY minute, however its being done. The only way to get a 100% PERFECT image (and that isn't always guaranteed) is to have a match to your screens resolution digital signal into a digital screen (excludes CRT b/c they really dont have a fixed pixel position). But even then the monitor still does corrections for screen placement, keystone, phasing, height and width corrections. So for me, the closest I can get without spending money on VERY expensive equipment is to use a computer monitor, and have my res set to the native res of the monitor. But then watching movies, all this has to take place again in the computer, so a 640x480 movie can play on a 1024x768. either way, its going to be there, no way around it, so commence beating of head on wall now... :bawling:
 
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