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Comment by birger | Hacker News Reader

If I understand correctly the idea is that you get a high-resolution display by putting two low-resolution displays in fromt of each other?

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This is not the first time that someone has stacked up two displays to get better output. About five years ago there was a paper about using a DLP projector to backlight an LCD display, yielding high dynamic range. Can't find the paper right now, can only find this poster http://www.cis.rit.edu/jaf/publications/2009/ferwerda09_vss_...

Like the LCoS hack at the end of this video, the DLP backlight suffered from registration artifacts and other crazy limitations. It's still a nifty idea, though.

Yeah, this is what I'm wondering about as well. What does the actual implementation of this look like? Is it just one display being fed 2 low-resolution image streams? And is there any effort required to synthesize the cascaded image?

I guess the main point is lower production cost. For 4k screen you need 4x more density pixels than a 1080p one, which is difficult to make with a high defect rate, by cascading two 1080p LCD you get as-good results but the cost is very cheap.

Besides you don't need to 4x your display bandwidth, just double 1080p.

Just my guess.

I guess this would also be a nice improvement for smartphones' screens since you would only need to power half the number of pixels for the same equivalent density which will save on the battery

Nya, the light will have to travel through two LCD layers, if I've understood it correctly. You'd need a very powerful backlight.

In the video, some of the captures for the cascaded displays were actually brighter (eg: 4:20 mark). I'm not sure why and it looked like they were just using a single display's backlight. Anyone know?

My guess is the opposite; it seems like cascading two 1080p LCDs ought to be more expensive than a single 1440p LCD which may have equivalent spatial resolution. The demo video doesn't address this; it says the cascaded display is better than a "conventional" one, but there are a variety of conventional LCDs available on the market.

> What does the actual implementation of this look like?

If you look at the video, the prototype "implementation" is just two display panels laid on top of each other. There's also another one involving projectors which involved more complicated optical setups.

> Is it just one display being fed 2 low-resolution image streams?

Yes, this is the impression I got.

> And is there any effort required to synthesize the cascaded image?

Yes there is but that was achieved in real time with GPU acceleration.

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