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For some reason Projector Central's reviews only mention upscaling/deinterlacing of DVD's, when I want to know how well they downscale 1080i/p content. I used to have an Optoma H30, best scaler I've ever seen, made HD content look amazing even at 480p. Is there anything similar at 720p?


For the record, I have an Infocus SP5000 (which isn't great at scaling 1080i/p), and its second lamp just hit its estimated lifespan, so I'm considering getting a new projector rather than just a new lamp.
 

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I could be wrong, but I think the reason no one mentions downscaling is because there's really nothing that needs to be done to convert the image other than ingoring some of the extra lines of data coming from the 1080p source. When you upconvert, the projector actually has to create the lines that are missing so there is some room for error/excellence in the way the projector creates those extra lines of detail.
 

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Except you have to figure out what information to remove - going down from 1920 to 1280 and from 1080 to 720, that's a lot of potential data they could remove. As I said, my old Optoma H30 was able to make HD material actually look HD, even at 480p - I paid $70 a month at the time to my cable company just to get the HD channels. Yet if I set the cable box to 480p to let it do the scaling instead of the projector, the image looked pretty bad. And my current 720p projector isn't very good at descaling 1080i/p - I get a better picture from HD-DVD's setting my Xbox 360 to 720p, for example, than setting it to 1080i and letting the TV to the downscaling.
 

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Quote:
Originally Posted by Dreamwriter /forum/post/0


Except you have to figure out what information to remove - going down from 1920 to 1280 and from 1080 to 720, that's a lot of potential data they could remove. As I said, my old Optoma H30 was able to make HD material actually look HD, even at 480p - I paid $70 a month at the time to my cable company just to get the HD channels. Yet if I set the cable box to 480p to let it do the scaling instead of the projector, the image looked pretty bad. And my current 720p projector isn't very good at descaling 1080i/p - I get a better picture from HD-DVD's setting my Xbox 360 to 720p, for example, than setting it to 1080i and letting the TV to the downscaling.

That's a problem with your XBox's upscaling to 1080i, or just outputting 1080i, not your projector. Honestly there is not much room for error in downscaling from a 1080i/p source to 720p. You just ignore every third line (I think).
 

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You always have to interpolate for non-integer scaling, be it upscaling or downscaling, or you lose quality. Just like how showing film content in 60FPS makes things juddery because some frames are longer than others, just removing lines would do the same sort of thing spatially.


That's not to say that there is no scaler chip that works this way - honestly, I don't even know since I don't have 1080p to downscale anyway - but if there is, it's lacking in quality. Period.
 
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