Does this exist?

Discussion in 'Displays' started by brettJconley, Nov 21, 2005.

  1. brettJconley

    brettJconley Extra

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    I hear all kinds of things about how this or that projector has a great picture in its native resolution but stinks if it has to scale anything. I was just wondering if any projector out there has an optical solution to this problem?

    My vision of the solution would be to start with the highest-resolution chip, say something with 1080 lines. In 1080p, it would be native resolution. Now, if you gave it a signal that was 720p, it would black out the top and bottom parts of the chip to leave only 720 lines of resolution, then use optical tricks to make the display the same size as the 1080-line display. For DVD, only use 576 or 480 lines, etc. Skip the scaling.

    Either there must be someone out there with a projector that does this, or else there's something wrong with the idea. Which is it?

    Brett
     
  2. ChrisWiggles

    ChrisWiggles Producer

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    what's wrong with the idea is that it's better to scale the image up, but the weakness is in the quality of the processing. Processing has gotten way way cheaper and better, but it still costs to do it right. The best solution is to buy a high quality scaler if the scaling in the projector is lackluster.

    Where your idea does have merit though is in displaying different AR. Most digitals are 16:9 AR, but many people watch a lot of movies wider than this, leaving panel resolution unused by black bars. Many high-end projectors or processors allow for anamorphic squeezeing of the image frame into a 16:9 frame from say a 2.35, and then you put an anamorphic lens on the projector to stretch things back out to 2.35, thus using more of the panel's resolution for those films.
     
  3. brettJconley

    brettJconley Extra

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    Okay, so to view a 2.35:1 show without wasting any resolution, the projector would have to use the full height of its video chip, and the anamorphic lens would stretch it out wider. Great. That makes sense to me. I don't suppose there are projectors out there that have all that built-in, so that all it would take would be the push of a button (or auto-recognition of the format)?

    Where do you get an anamorphic lens? And do you have to get one to match a projector, or are they generic? And do you have to manually put it on/take it off every time you change movies? I'm sure the guys with the ceiling mounts wouldn't be doing that all the time. I guess those guys would be the ones doing the scaling.

    As far as projectors go, though, what do I look for to know how a projector can handle 2.35:1 movies? Any 16:9 projector I'm sure will handle them by putting black bars on the top and bottom, but do some projectors have a stretch mode that allows you to use the anamorphic lens, while others don't? When I'm researching projectors, what do I look for that tells me this?

    I used to work in a movie theater and I still remember having to slap on the anamorphic lens after the previews just before the movie came on. I don't think I'd mind doing that if I had to. It's way better than black bars on the screen.

    Thanks,
    Brett
     
  4. ChrisWiggles

    ChrisWiggles Producer

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    There are. They are also very expensive. You can do this manually, though. Some lenses that you can buy aftermarket are motorized by remote, which is easier, but you still do have to manually select the stretch in the projector and set the lens, not quite as integrated but handy.

    panamorph is the lenses most commonly used in my experience.
     
  5. brettJconley

    brettJconley Extra

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    Okay, that's cool. I found panamorph's site and I think I understand how it works. And for $500, it sounds like a great idea.

    But tell me again why a 576-line DVD would look better scaled to 720 lines. 576 does not divide evenly into 720, so each frame is going to have to have some lines doubled up and others not. It seems like the most perfect image would be produced in the source's native resolution.

    Please convince me on this.

    Thanks again,
    Brett
     
  6. brettJconley

    brettJconley Extra

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    Okay, sorry I haven't waited for anyone to respond, but I've been looking for a combination of things that will do what I want, and I'm having trouble finding it.

    I went to Panamorph's site and on their "Overview" page, they describe 3 application modes. My vision of my home theater would fall into the #2 mode, which is to permanently fix the anamorphic lens in front of the projector and use a scaler (unless the projector happens to support all this) to stretch or compress the image appropriately.

    I've tried looking at scalers, but I can't make heads or tails of which ones can handle this aspect ratio conversion. Who has a recommendation to get me started?

    So to do this right, I would start out by taking my 16:9 projector and make it shine a standard 16:9 image so that its width fills my 2.35:1 screen (so it will shine above and below the screen). Then for 2.35:1, the image is stretched to use all available pixels (unless it's already an anamorphic image), making it show above and below the screen, and the lens squishes it back to screen height. For 16:9 (or 4:3, which already has the black bars on the sides, right?), the image is compressed horizontally by the projector or scaler, and then the lens squishes it vertically, restoring it back to its original aspect ratio. Good so far, right? That will mean that I'll be losing horizontal resolution on 16:9, right?

    The only way to fix that would be to remove the lens for 16:9 and 4:3 shows and change the zoom of the projector so that the image fills the height but not the width of the screen. I guess that's definitely the cheaper way to go, but it would have the added benefit of not losing any horizontal resolution, right?

    Thanks again,
    Brett
     
  7. Jack Gilvey

    Jack Gilvey Producer

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    I think you understand the concept just fine, Brett.


    Correct all around. A royal PITA, I say. Using a fixed-offset pj with limited zoom, the image winds up too high with the lens removed due to the drop induced by it. In addition, there's not enough zoom range to match 2.35 and 1.78 screen heights. I left the lens in place and suffered the indignity of resolution loss.
    With my current Panasonic AE900, I don't have the ability to scale the image properly, but I do have lens shift and enough zoom to get things squared away with or without lens. In fact, there's enough zoom that I haven't been using the lens, just zooming 2.35 to fill the screen and reducing the size for 16:9.

    http://www.avsforum.com/avs-vb/forumdisplay.php?f=117
     
  8. brettJconley

    brettJconley Extra

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    No way. How did you find out it was $500 at Staples on Friday? (I haven't seen the ad.) Is that like $1000 then $500 rebates? That is awesome. I don't suppose that's available for that price on Staples.com?

    While I'm at it, where do you buy the panamorph 752? I see it on Panamorph's website for $495, but are there other places you can get it? Is it very common to find them used on Ebay or elsewhere?

    Thanks,
    Brett
     
  9. Jack Gilvey

    Jack Gilvey Producer

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    http://staples.shoplocal.com/staples...%3d-2099986987

    It's a refurb, but how can you lose with "2-year mfr limited warranty parts, labor and lamp"? I don't need one, and I just gave mine to my brother, but I feel like a jack*ss passing it up...

    Pretty sure Panamorph is the only source for the 752 (original retail was $2200 or something). E-bay is always a possibility, as usual.

    At $1000, this combo will embarass your friend's goofy 42" million-dollar plasma...and the colors won't look alien.
     
  10. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    So what happens when you get a 2.20:1 film? or a 2.76:1 film? You'd need specialized lenses for every single different aspect ratio out there.

    Regards
     
  11. brettJconley

    brettJconley Extra

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    Thanks, Michael, but I'm really not worried about the others. I'm a mainstream watcher, and the only things I've ever seen are 4:3, 16:9, and 2.35:1. I'd be very happy to have a system that makes those three look good, and to tell you the truth, I'm not even worried much about the 4:3 experience.

    I'm sure there are a lot of other ratios out there, but I would not be surprised if I die without having seen any.

    Brett
     
  12. ChrisWiggles

    ChrisWiggles Producer

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    not really michael, you are still using more of the panel even if the movie is wider still. Think of anamorphic DVDs, there are tons of ARs out there, and wider ARs still have black bars encoded anamorphically, but the active picture is dedicated a lot more pixels in the encode than it would be non-anamorphic. The same goes here. A movie wider than say 2.35 would be dedicated fewer pixels of the 16:9 panel than a 2.35 film, but it would still be a LOT more than without the anamorphic lens and displaying a 2.2 firl or whatnot on the 16:9 panel, as there the black bars at the panel would be MUCH huger, so much fewer pixels are being used for active image display.
     
  13. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    So the question is ... are you simply drawing a line saying that that is good enough rather than following the argument that each film's aspect ratio must be maximized to the available pixels?

    Something always suffers ... and 4:3 material would suffer the most. Who gets to say that 4:3 material is less important than 2.35 material?

    Regards
     
  14. ChrisWiggles

    ChrisWiggles Producer

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    well, it's unrealistic to have precisely an anamorphic lens for each ratio of expansion you'd need for every possible AR, just as it's unrealistic to have a dozen different kinds of anamorphic strecthes on DVD or anything else. Indeed, with the AR lens installed 4:3 material would suffer less panel resolution than it would without the lens. This is why you add/remove the lens as needed. Indeed, 16:9 material would also suffer, you would not want to use the lens when viewing 16:9 material as it would degrade the picture in terms of resolution.

    Keep in mind there are also lens distortions introduced, so the improvement is in some sense offset because it isn't just an improvement of active resolution, but also an introduced negative of barrel distortion and chromatic aberrations etc. Still, if a great deal of 2.35 material is viewed (which is usually the case in many HTs) there can be a decent improvement overall if done properly.
     
  15. Jack Gilvey

    Jack Gilvey Producer

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    Another nice post, Chris.


    Yeah, although lenses such as the Prismasonic 1200 horizontal-stretch model have a bypass function available which makes thing easier...even a motorized one for the particularly well-heeled or lazy. [​IMG] When using the Panamorph 752 vertical lens, I left it in place and, even though there was horizontal resolution loss, I didn't really notice it...apparently vertical resolution (which is fully preserved) is more important.
    With a 720p panel, I think you'd be preserving all the source resolution on a DVD anyway, even if horizontal scaling results in using less than full panel resolution.
     
  16. ChrisWiggles

    ChrisWiggles Producer

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    yup!



    It's too early in the morning for my brain to tackle this fully, but I don't think it's quite the case because I still think you'd be using more than 720x480 pixels, certainly more than 480 vertically, plus you still have the confusing issue of square panel pixels which now aren't through the lens, and non-square source pixels. This is why I'm a CRT guy, and why I quit math long ago! [​IMG] It certainly won't look bad by any means if you're lazy and leave the lens and squeeze going, people do run it this way to have constant height setup which is not totally idealized for 16:9 content, but is idealized if you watch mainly 2.35 stuff and are lazy [​IMG]
     
  17. ChrisWiggles

    ChrisWiggles Producer

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    yeah, i interpreted your earlier post about the "full DVD resolution" as being something more 1x1 mapped native, my mistake. It still would be better technically to remove the lens and use more pixels horizontally, but cinematically it's pretty impressive to have a constant height system. I've considered doing this on a CRT, but the phosphor wear is just too big an obstacle IMO, one that isn't a problem with a digital.

    edit: drr.. constant height not constand width! thanks jack!
     
  18. ChrisWiggles

    ChrisWiggles Producer

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    yes, i did mean constant height :b
     

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