Hd channels?
Answer:
Why not just use the channel's native resolution? Discovery Channel HD is broadcast in 1080i, as are most HD channels (at least in my area). The only HD channels transmitting 720p here are FOX-HD, ABC-HD, and ESPN-HD. I just set my cable box to display the native resolutions of all channels; I think you get a better picture that way. The SD channels I don't even upconvert, I just display them in regular 480i. Both 720p and 1080i look amazing. 720p is better for fast motion as others have pointed out (which is why ESPN is broadcast that way, with all the sports they show and all). Other than that, you would have a hard time finding any discernable differences between the two. Just set your cable box or whatever to display the native resolution of each channel. You'll get a better picture.
I have HD channels from my cable company and had the same sort of issue. with 1080i you only see half of that number every time the screen refreshes which is every 30th of a second. With the 720p you see all 720 lines every 60th of a second because they all refresh at the same time. So progressive technically should look better because the entire screen refreshes at the same time instead of every other line as with interlaced (i). After all of that though, I still thought the 1080i looked better. Confusing huh?
fast moving images, 720p. Other, 1080i. Interlaced means it takes 2 steps to get all the lines displayed, and if the image has already changed by the time the second step is going, then you get bluring.
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