720p vs 1080i

[Schwarz]

So I will start this with my own analogy and along the way you guys can tell me if i'm right or wrong.
The difference between 720p (progressive) and 1080i (interlaced) is that for every 1/60th of a second in 720p all your lines are refreshed.
But in 1080i you are actually having 540 lines refreshed in 1/60th of a second then the other 540 at another 1/60th so basically to refresh your whole screen it takes 1/30th of a second.
Now your brain doesn't notice it in slow moving images but it seems that in fast action you could see some degradation of the image.
Now what I want to know is that let's say I have a video game console that can be put in 720p or 1080i what would be the best for gaming and then what would be best for movies.

Now I am talking about image quality because if you really look at it at 720p the image is displayed really at 720 a cycle but in 1080i it only shows 540 a cycle. (cycle meaning 1/60th of a second)
Using this same logic if I am refreshing 1080 in 2 cycles with 1080i then I would be refreshing 1440 lines in 2 cycles at 720p.

Of course its a little like comparing apples to oranges since even though I am refreshing slower on 1080i I still have a higher line count on my screen (higher resolution, crisper image) then at 720p even though 720p could refresh faster I am still limited to 720 lines on my screen.
So basically this all comes down to Resolution vs Refresh Rate.

[PP Mguire]

Arent they coming out with 1440P? And thanx for kinda clearing that up for me. I had no idea what that I and P stuff was. And sorry for not answering your question.

[Pat123]

Gaming 720p i would say just to make sure your getting the best picture. Movies im thinking 1080i.. However if this games console has wireless controllers moving a distance back will help increase the viewing pleasure.. I dont really think there is a massive difference in quality. Google it or try IGN.com they seem to have plenty of comparisons..

[Schwarz]

Yah i've seen image quality comparison but I haven't seen video comparison.
Because I want to see the difference between let's say the full progressive scan of a frame at 1/60th of a second and an interlaced refresh of 540x2 in 1/30th of a second...

[PP Mguire]

Ok i dont really understand this correctly so correct me if im wrong but.

Wouldnt the 1080 be better?

720 in 1/60th of a second

or

1080 in 1/30th of a second? (Judge basing off what you just said in last sentence)

[ghidora]

Schwarz, I responded to you thread about the HDMI on XBOX (http://www.bjorn3d.com/forum/showthread.php?t=14025) before I saw this thread. I added some info there you may want to look at.

I will add 2 cents more here. ;-)

On an LCD/Plasma/LCoS(SXRD) TVs, and maybe on DLPs, they render each half frame to a frame buffer in 1/60th of a second and then display the whole frame on the screen, so you are seeing all 1080 lines (1080i) or 480 lines (480i) at one time. This gives you the 30fps rate. When they render a progressive scan frame (480p, 720p and 1080p), they render the entire frame to the back buffer in one pass and then display the buffer on the screen. This gives you the 60fps rate.

Only in old CRT TVs did they render each half frame to the screen directly. The net result is still 30fps but the image was jittery.

[PP Mguire]

So basicaly you want p instead of i?

[westy87]

Oh p>i for sure, when they are the same amount of lines, but its just hard to compare 720p with 1080i. Like, do you want more lines, or better refresh rate, etc. I tried figuring it out a while back but, it beats me

[PP Mguire]

Hmm with something close like that, prolly better refresh like with the whole CRT thing. But, i could be wrong.

[ghidora]

720 is not that close to 1080. We're talking about 360 more lines, not to mention that 720p only has 1280 columns compared to 1920 for 1080i. Would you rather look at your monitor in 640x480 or 1024x768? That's a similar comparison. ;-)

Of course, how close you sit to your TV greatly impacts your ability to see the difference in resolution. But I can tell you I sit about 11 feet from my 60" widescreen and I can tell the difference in image clarity between 720p and 1080i. I prefer the higher resolution. You'd have to experience them both with the same content in order to truly know which one you prefer. And it is just that, a personal preference. ;-)

[Schwarz]

It all comes down to resoution vs refresh rate.