What looks better between a DVD upscaled to 720p and one upscaled to 1080i?

[Mulder]

Can anyone tell me what their personal preference is?

[zdefonte]

Both look the same to me...craptacular! Although I will admit that a few titles upscale fine.

[Chris Gerhard]

It is very difficult to tell the difference, but I upscale to 720p when using a 720p display and upscale to 1080i when using a 1080i display. If using a 1080p display, upscale to 1080p or 1080i depending on player and display.

Chris

[Jish]

If your display supports full 1080 resolution I would probably pick 1080i - of course it depends how good a job your DVD player does of upscaling...

[richard lichtenfelt]

1080i is better resolution and more information than 720p. The difference between 1080p and 1080i is simply that for interlaced the lines are displayed first by shooting all odd lines then all even lines, for progressive scan the lines are shot onto the screen in true succession line 1,2,3 etc. This all happens much faster than the human eye can detect. 30 times per second. I.E., movies are projected at 24 frames a second, can you tell where one frame ends and the next begins? Does a movie blink when you watch it?
The difference is only noticeable if you are sitting in front of a 46" or larger screen at a distance of no more than 5 feet away. Primarily as it applies to television, (p)rog. or (i)nter. is more of a marketing ploy than anything else. A tactic used to convince someone to spend an extra $1,000.
To answer your question, the 1080i picture will be more detailed and vibrant than 720p.

[Mulder]

Thanks for answering my question guys!

[Frode]

Originally Posted by richard lichtenfelt

To answer your question, the 1080i picture will be more detailed and vibrant than 720p.

On a CRT HDTV, yes. On a digital display either 720p or 1080p is going to look best - 1080i will most likely have issues because the display will have to do another conversion pass to convert it to progressive, and depending on the scaler that can vary from looking "okay" to "very bad". The amount of scaling necessary is also a factor - if you don't have a full 1080p native set, then 720p might look better since you'll only be upscaling. If you feed a 768p set 1080p it'll first be scaled up, and then scaled down to fit.

Alternatively, you can just output 480i or 480p and see if the set's scaler and deinterlacer is better than the DVD player's. Most of the cheap upscaling players actually tend to be worse than the ones built-in in modern TVs. You really have to try the different options yourself to see what works best.

EDIT: Incidentally, progressive vs interlaced is not a marketing ploy. A progressive display will effectively have twice the resolution of an interlaced one for images that are in motion.