1080i vs 720p


If one has a 720p projector which can output at 1080i, is it better when using regular dvd source or HDTV to watch in 1080i or use my Faroudja processor and watch in 720p, technically speaking that is.
jcbower
Post removed 
Elizabeth, correct but don't forget that when shown on a 1080p display, 1080i is displayed at 1080p-- twice the information is actually on the screen compared with 720p.

So as the quality of processing and screen size increases, 1080i should, and often does, look better than 720p. However, in most circumstances, these 2 resolutions look remarkably similar.
OK, here's where I've got to call foul...

"1080p has TWICE the data of either 720p OR 1080i"

1080p and 1080i transmissions have the SAME amount of data (1080 lines). The only difference is that the 1080i is transmitted to the display in 2 groups of 540 lines (even & odd) while the 1080p is transmitted in one pass, top to bottom. The amount of data is the same. It's not like 1080i is repeating the same 540 lines.

In theory, 1080i is better than 720p especially if you are talking about a static picture. The problem arises when motion is thrown in to the equation.

Bigbucks5, Yes but don't forget that (in the US) video is recorded and displayed at 60 Hz. So with 720p, 60 frames/second are recorded at full 720 resolution. 1080i is also 60 Hz, but each frame takes 2 cycles to record (1 cycle each for the even and odd lines per frame).

So during the course of displaying over 1 second, regarding the total amount of data handled, 1080i displays exactly half of 1080p, and approximately the same amount of actual data as 720p. But like you said, on the screen at any given time, the amount of data is the same between 1080i and 1080p.