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Questions about 1080p
shmokes:
I have heard a lot of people say that on screens about 42" and below nobody can tell the difference between 1080p and 720p. I've never done any comparisons myself, but I don't see any reason to disbelieve this. On the other hand, though, I've read a lot of reviews and such in which people people say that standard definition TV looks terrible on a 1080p screen compared to a 720p screen. One part of my brain immediately starts putting things together and goes into skeptical mode. I say, "Wait . . . if I can't tell the difference between 720p and 1080p on a 42" screen, why does this stuff look terrible on one, but passable on the other?"
I've come up a plausible answer for that, in that it must be excessive artifacting and ---Cleveland steamer--- that's introduced when the signal's resolution is upconverted that high, whereas there's much less data to add in order to upconvert only to 720p --- thus, 720p ends up with a superior picture.
Unfortunately, this begs another question. Why, then, do DVDs look so great when upconverted to 1080p? Can someone help me understand what I'm missing here?
Dexter:
You can definitely tell the difference between 720p and 1080p depending on viewing distance. I've been looking at screens in both resolutions in stores and depending on screen size and viewing distance, theres a noticable difference depending on brand.
As for upscaling, I think different manufacturers use different chips, so results vary depending on algorithym used per mode.
Are you thinking of buying one? Theres good online reviews of pretty much everything out there, but before you part with your cash try viewing your perspective buy at the distance you'll be viewing it at home and see if it agrees with you.
Crap thing is, every retailer seems to have their sets adjusted differently so be sure to play around with the settings instore if you can.
MaximRecoil:
--- Quote from: shmokes on January 06, 2008, 08:23:19 pm ---Unfortunately, this begs another question. Why, then, do DVDs look so great when upconverted to 1080p? Can someone help me understand what I'm missing here?
--- End quote ---
DVD's are at the bottom end of "HD" (480p). This is quite a bit higher resolution than "standard definition TV" which translates digitally to about 320x240, plus it is interlaced, as per the NTSC standard for broadcast TV in the U.S. In PAL format, the resolution of DVD's is even higher (576p), which isn't all that far off from 720p.
Keep in mind that NTSC DVD's are also interlaced for compatibility with the NTSC video standard, but with DVD's that were sourced from film (e.g. a typical Hollywood movie) the progressive video is still there. "Progressive scan" DVD players can IVTC on the fly and only display the progressive frames.
The way this works is, when a film (~24 FPS) is transferred to NTSC DVD video, it is telecined. This adds 2 half (interlaced) frames for every 3 full frames (AKA: 3:2 pulldown). This results in a partially interlaced video of ~30 FPS (29.97 FPS). This is done for NTSC compatibility reasons. This was done long before DVD came out too. It was used for putting film-sourced movies onto e.g. VHS, and also for broadcasting film-sourced movies over the air.
So a "progressive scan" DVD player will IVTC (inverse telecine/3:2 pulldown removal) the DVD on the fly, i.e., it discards the 2 interlaced frames for every 3 full frames that were added during the telecine process, so you end up seeing only what was in the film in the first place at ~24 FPS.
If the DVD video was sourced from video in the first place (rather than film), then all of that is irrelevant. It will play the same on a "progressive scan" DVD player as on an older non-progressive scan DVD player—in other words, it will always be interlaced, because the source video itself was natively interlaced. You usually run into this with older TV shows, especially sitcoms, that are put onto DVD. Most of the sitcoms from the 80's for example, were shot on Betacam (video) rather than film. The bigger budget shows, e.g., Magnum P.I., were usually shot on film, thus you get a far better DVD transfer.
I got off on a tangent there, but the short answer is, DVD is of a substantially higher resolution than standard definition TV, so it looks better when "upconverted", because it doesn't have so far to go in order to get there.
ahofle:
Interesting. I thought all source material on DVD was 480i.
Samstag:
--- Quote from: shmokes on January 06, 2008, 08:23:19 pm ---I have heard a lot of people say that on screens about 42" and below nobody can tell the difference between 1080p and 720p.
--- End quote ---
There are any number of reasons this gets tossed around as "common wisdom":
A) People saying it are unaware that their 1080p TV is actually 720p resolution and just happens to accept a 1080p signal.
B) They may be unaware that the incoming signal can be in 1080p format but originate from a lower-quality source. For example, a lot of recent Xbox/PS3 games render a resolution lower than 720p due to lack of processing power, then upscale each frame to either 720p or 1080i/p. In that case you may not see a difference between two TVs.
C) They focus on the individual pixel size and don't notice the extra aliasing you'll get on a 720p when displaying a 1080i/p source.
D) They heard it from multiple sources on the internets, so it must be true.
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