Cascaded Displays: Spatiotemporal Superresolution

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Cascaded Displays: Spatiotemporal Superresolution

Postby bertrand7d5 » 23 Jan 2016, 02:15

Cascaded Displays: Spatiotemporal Superresolution using Offset Pixel Layers
phpBB [video]

https://research.nvidia.com/publication/cascaded-displays-spatiotemporal-superresolution-using-offset-pixel-layers

I was thinking that you could combine two LCDs to improve contrast and/or implement a scanning backlight. Then, I found this video.

They take two LCDs and make one higher-res and higher-fps display by staggering the refreshes.
They demonstrate its use for a prototype VR head-mounted displays (HMDs) and also used with cascaded LCoS projectors. This could be one way to get higher detail without extra bandwidth (sending 2 frames @ 60fps vs 1 frame @ 120fps) or needing higher-density (see caveat below), higher refresh LCDs.

Caveats: Because of LCD color-filters (subpixels), they actually purposely lowered the resolution on each LCD using either 2x2 or 4x4 groups of pixels, so actual results are no better than the original panels (except for faster refreshes). Second, because of a gap between the two LCDs, viewing angles (parallax) changes the offsets affecting the results (noticeable in the video for the prototype HMD). Timings of the LCoS (or alternatively DMD) projectors may need synchronization for best results. Finally, there may be additional latency added for processing when using staggered refresh mode.
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Re: Cascaded Displays: Spatiotemporal Superresolution

Postby Hyperboreus » 23 Jan 2016, 17:32

Hello!
I thought about something like that in terms of to ameliorating contrast ratio and colour depth, resolution too.
The interesting thing. :)
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Re: Cascaded Displays: Spatiotemporal Superresolution

Postby RLBURNSIDE » 24 Jan 2016, 15:26

Hyperboreus wrote:Hello!
I thought about something like that in terms of to ameliorating contrast ratio and colour depth, resolution too.
The interesting thing. :)


I was skeptical about the claims of increasing resolution with stacking projectors but it does look sharper. Quite often with 3 chip DLPs vs 1-chip DLP the 3-chip version isn't as sharp because it's very difficult to align the 3 light paths perfectly. Perhaps NVidia has found a way here to turn a negative into a positive, at least insofar as stacking two DLPs together and actually increasing resolution instead of effectively decreasing it.

Doubling the lumens is the typical use of dual projectors. But you wouldn't increase the native contrast ratio unless you were doing pseudo-HDR, and even then, the black level will double so the low end of the DR will have half of the native contrast ratio no matter what you do.

Colour depth is easy though, buy a Benq w1070 for 600 bucks and you've got a 10-bit projector with there. If you want to boost the gamut from rec 709 to dci P3 you can also do that with a yellow notch filter, but those cost a few hundred bucks and 25% lumen drop, so probably not worth it to most people.
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Re: Cascaded Displays: Spatiotemporal Superresolution

Postby sharknice » 24 Jan 2016, 15:59

Isn't this the same thing as interlaced resolutions on CRTs?
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Re: Cascaded Displays: Spatiotemporal Superresolution

Postby RLBURNSIDE » 25 Jan 2016, 08:22

sharknice wrote:Isn't this the same thing as interlaced resolutions on CRTs?


Not really, both images are in full res stacked one on top of the other. The main difference is they are offsetting the image of one of them with some kind of smart dither pattern in order to achieve better anti-aliasing. It seems like they came up with anti-aliased displays, which is super cool. I'm actually kind of surprised by how good it looks considering. I mean, it looks similar to 4x the # of pixels (twice the resolution) but at only a cost of 2x (2 LCD panels or 2 projectors). Also, the wonderful thing about it appears to be that there is no loss of light going temporally staggered. I mentioned an easy algorithm to double your refresh rate using two projectors, but it involves alternating which projector is masked for 1/2 the frame time. Of course that would need hardware haxx too in order to achieve but it could be done. This way seems all around better, full lumens out of both projectors with double the resolution and double the effective framerate too. Fantastic.
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