Hi all,
Thanks to JohnK and Capn_Pickard for pointing out some essential truths, including the fact that DVDs hold interlaced signals (if they were encoded as progressive images, consumers with older TV sets wouldn't be able to view them). I'm late posting to this thread because other Axiom tasks kept me away, though I've followed the thread.
One fact that everyone should understand is that if you have an HD CRT set, its "native resolution" is 1080i -- it will scale any incoming signals to an interlaced 1080i presentation.
All other HD fixed-pixel arrays (DLP, LCD, plasma) have a native resolution of 720p. This means that although broadcasters prefer to transmit a 1080i signal rather than 720p, because less bandwidth is required (the video information is transmitted in alternating fields every 1/60th second, whereas a 720p signal presents all the video information 30 times per second). So if you ask which looks better, 720p or 1080i, it's meaningless, because if you are using a DLP or LCD front or rear-projector, it will automatically scale the incoming 1080i signal to 720p in order to display it. Such a comparison would only be possible if you had an HD CRT direct-view set (or projector) displaying the native 1080i signal next to a DLP/LCD device displaying the 1080i signal scaled to 720p, which it must do to display it.
A small correction to Capn_Picard's post: the deinterlacer in a DVD player may indeed add aberrations and video artifacts if it's a cheap or poorly designed deinterlacer. It's fairly costly to put in a high-quality deinterlacer so you generally won't find it in cheap DVD players. Consequently, the deinterlacer in your HD set or HD projector may be superior to the one in the DVD player, in which case you'd get a better quality picture with fewer artifacts by setting the DVD player to interlaced output and using the HD set's deinterlacer and scaler to do the processing.
This also applies to some inexpensive DVD players that have built-in scalers with DVI or HDMI outputs. The chip set is mediocre, so often the "upconverted" 720p signal done by the DVD player and sent through its DVI or HDMI output is not an improvement over using the analog component video outputs. In some cases, it may actually be inferior.
Added to these factors are certain personal judgments and biases brought by the viewer as to what "looks better." Joe Kane, the guru of Video Essentials, likes everything to have a kind of "filmic" look, which to my eye appears slightly soft, smooth, a bit dark, and lacking contrast. With video material, I don't want a "filmic" look. It's video we're watching (admittedly, with lots of DVD movies, it's film transferred to video) and I prefer a slightly punchier, contrastier, sharper image. I certainly don't want a soft "filmic" presentation for live HDTV sports and outdoor events. So keep your own biases in perspective when engaging in discussions of video image quality.
Finally, another question posed is whether 1080p looks better than 720p (because a new generation of Texas Instruments DLP chips will display signals as 1080p). Viewed side by side, which I've done, there is a slight improvement. Sometimes it's really hard to discern. At the moment, no broadcasters are transmitting 1080p, and I doubt it will happen for a long time because of the huge bandwidth requirements. The comparison I viewed was on two 61-inch HD DLP rear-projection sets, side by side. With larger screen images and front projection, the differences would likely be more apparent, but I haven't seen a demo like that yet.
Regards,
