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Discussion Starter · #1 ·
I am a newbie to projection tech and I was wondering if there is anything on the horizon that will eliminate the need for scaling algorithms?


On the Silicon Light Machines PDF brochure they mention this about GLV tech:


"Variable Aspect Ratios


The image width can be varied by simply varying the scan amplitude, so the Scanned Liner GLV architecture maintains impeccable image quality across a wide variety of screen aspect ratios, without the need for expensive anamorphic lenses or image-distorting scaling algorithims"


You can d/l the pdf on silicon light machines webs site or here: http://www.siliconlight.com/brochure1.pdf


Now while I don't know how GLV works in practice, this seems like a good idea in theory and I was wondering if scalers are needed it tech like D'ILA and DLP....


Is GLV tech the only one that addresses this issue?
 

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Interesting read. However, the GLV appears to be a variation on existing micro-mirror display technology as used in DLPs. The drawback to "gating off" a section of the panel, is that the corresponding areas of the screen would then have no image display, the picture would not fill the screen - unless you scale the source to fill as much of the screen as possible.


This GLV sounds like a solution for special applications, but it doesn't seem like a home theater product with wide acceptance unless you also say design a projector with a huge optical zoom range so that whatever portion of the panel used would also fill up the display screen to the maximum image size. The reason for this is source material comes in a variety of aspect ratios and resolutions. The common aspect ratios are 4:3, 16:9, 1.85:1, and 2.35:1 but there are many others.


There is a new projector from PLUS which largely eliminates scaling, the HE-3100, aka the "Piano". It has the ability to display 480p in 16:9 aspect ratio as 848X480 resolution without scaling, and 4:3 as 800X600 without scaling - but it would of course, still have to scale or be fed a scaled signal for 2.35:1 widescreen, or 720p/1080i HDTV.


There are also 16:9 native aspect ratio projectors which can display 4:3 on the center of the panel (constant height setup), but they are of course expensive. Nor can you avoid scaling common 2.35:1 widescreen movies to 16:9.


Scaling is a pretty unavoidable fact of life given the freedom that Cinematographers feel to use any aspect ratio they want - or invent a new one, which for a film projector, is a small setup fee to "file an aperture plate".


The user-hostile HTPC is one inexpensive way to get a variety of scaling options for a fixed-resolution projector. Anamorphic lenses help although sliding one away or back in place for standard and widescreen requires projector focus and position tweeking.


As yet, there is no perfect answer.


Gary


[This message has been edited by Gary McCoy (edited 10-03-2001).]
 

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Discussion Starter · #3 ·
So you are saying that even when they vary the scan amplitude of the GLV element to whatever res needed there would still be blank parts of the screen?


Since, in theory, there would be no worry of burn-in on the GLV, that doesn't seem so bad.....


You may not know this but back in July 2000, Sony licenced GLV technology for use in consumer front/rear projection products:
http://www.siliconlight.com/htmlpgs/...nframeset.html


"In the initial six months of the agreement, Silicon Light Machines will conduct a transfer program of GLV technology to Sony. After that time, Sony will initially concentrate its efforts to develop GLV-based front projectors for the industrial market, then work to develop GLV-based rear projectors for the consumer market."


Hopefully we will here more about this at CES....

 

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KLee? *squints* is that TP Kenneth Lee?


------------------

/frode
 

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Klee, yes, that's how I see it, because the GLV is not analog, it only has "on" and "off" states. Say for example that the source resolution is a 480p signal in the following aspect ratios: 4:3, 16:9, and 2.35:1, and the progressive DVD player has been set for 16:9 output and we have a 16:9 screen. Assume further that the GLV display has 1080 vertical pixels and the ability to scan horizontally up to 1920 pixels.


Assuming no scaling but "gating off" the unused vertical pixels, the 4:3 image occupies the center 480 pixels of the 1080 vertical array, with 300 unused pixels above and below the active pixels - and the display scans the pillarbox bars to either side, so we get a tiny image with black all around, unless the projector can optically zoom the active 480p area to the full screen height.


The 16:9 case is not much better, just wider - the pillarbox bars are missing, but we still have 300 unused pixels above and below the active area. There is still black all around the image - ridiculous to show a 16:9 signal in the middle of a 16:9 screen, don't you agree?


The 2.35:1 AR signal is worst of all, as the letterbox bars are large - I'll leave the math to you.


So, don't get me wrong, I see the GLV as a great way to get large, variable width/variable AR displays for cheap, but I don't buy the "no scaling" part - when the source vertical resolution is not 1080 lines, you have to either scale or zoom the image to fill the screen height somehow. I also have misgivings about sweeping one row of 1080 pixels through 1920 column positions, as the duty cycle of each pixel is then only 1 / 1920th of the total illumination.


Still - I look forward to seeing it.


Gary

 

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Discussion Starter · #7 ·
Quote:
Klee, yes, that's how I see it, because the GLV is not analog, it only has "on" and "off" states
Again, this is not entirely correct....


From the pdf brochure, it states:



"Non-Liner optical response for Continuous-Tone Images


The GLV technology uses digitally-generated signals to precicely position the ribbons *between* the two limits of "on" and "off",thereby diffracting a specific ratio of light.This optical response creates a non-liner continuous grayscale with wide dynamic range, an advantage that is particularly noticable in dark scenes.
http://www.siliconlight.com/brochure1.pdf


So besides the fact GLV is not just an "on" and "off" display device and can indeed reproduce a correct grayscale image, I am still at a loss as to how they get by without scaling....
 

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Klee,

The GLV does not require scaling because it can output a native resolution at anything up to the size of the array in the vertical dimension and for all practical purposes any horizontal resolution.


So with the 1080 pixel part they are describing you can display any resolution all the way up to 1920x1080 with no scaling!


This technology can do this because the switching rate of the device is high enough to render 1 column at a time and move across the screen at fast enough to keep up with video frame rates.


One really nice thing about this technology is the low number of pixels will help make this device more reliable. Of course 1 pixel out means a missing line on your screen so any failure will mean chip replacement.


Does anybody know how close Sony is to releasing a product using GLV?


What Gary is talking about is not a scaling issue. Matching the output to a screen size is only a projection of light issue that must be handled with optics. Scaling refers to changing the digital resolution. This is required for devices that only can display one resolution. Because the GLV can display any resolution, it does not need scaling. A GLV projector will need a zoom to resize an image to the screen.


Aspect ratio is another issue but is also not scaling. Changing aspect ration just means the height to width is different. You get a letter box on your screen because the screens aspect rationdoes not match the projected images aspect ratio. This means you either need multiple screens or you will have bars on aspect ratios that don't match your screen. There is absolutely no reason to scale a 2.35:1 image to 16:9. That makes no sense.


--sdc

--sdc


 

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The GLV technology has been licensed exclusively to Sony. This will probably delay introduction of consumer devices for two reasons. One is Sony has stated they will produce commercial devices with this technology first. Second is they are using lasers in their display. Lasers have great color saturation and are probably the best way to go for quality but the cost is still high and that could cause further delay in consumer products.


--sdc
 
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