DIY 'Infinity Contrast' Display (projector-LCD-backlight mod) development thread

I'm not super familiar with OBS, how exactly does one use both a video while also the custom luma key & glow behind it?

Thank you for another wonderfully interesting video. 

I wonder how well this concept would work on a overall smaller scale, with a monitor, It would still be overly large but potentially worth it for people who want a quality monitor. With the smaller display size it (Heavily may) be possible to potentially place the projector in a vertical stand with the mirror to reflect. Making it more vertically sized and easier to justify. The smaller display also should increase the brightness. 

I wonder if there is a good way to get this to work with HDCP protected content, like Netflix and Hulu. In the video the projector is running off of VGA which would cause issues with HDCP and I wonder if it may be more worth it to get one with HDMI or DVI. It would also be an issue with a tool like OBS being used to apply filters. 

With the alignment of the display and projector I wonder how the OBS settings would relate. 

Very interesting. It got me registered on the forum. I wonder if more light would improve the image quality or we're already at diminishing return? 

Very interesting, the LED mod would be really cool to see , maybe if you make a part 2 video. And could also try to make a stand with more accessible parts, i have a LG TV that it wont last too long now and when it dies i would be willing to try, but i wouldn't be able to make a stand as you did since i got no professional tools 

@wreper12 If it's still up you can use a hdmi splitter because only the first source is cripted but the rest of the splitted signals are not you can then make any manipulation you wan't on them

But How did you played the same media at tv and projected at the same time?
Did you just press play button on both the devices at once ? or
OBS has a feature to stream same media on two devices with different output settings?

I wonder if the space issue can be solved by putting the projector infront and below the screen to essentially turn it into a short throw projector.
Shine it at a mirror that throws the image up, then reflect that image with a secondary mirror that faces down back onto the screen.

I wonder if this is still doable with a 3LCD style projector (most short throws on ebay use the 3LCD instead of DLP tech) or if the brightness would be too low. With this kind of upcycling a used laser projector would be less than ideal as you replace the projector instead of the bulb when the laser dies IIRC. 

I'd also be into seeing a part two or something with the full setup. My thought is its done with some kind of "triple monitor" style setup. Main monitor running to the LCD with your video player of choice. the other two are a regular monitor and the projector, setup to duplicate each other, to setup OBS and then launch the full screen OBS preview.  I'd be curious what a "final" install would look like also and can it be done in a way that's family friendly if the HTPC has to reboot or something. Like I can picture it being fully normal usage to the end user if it was possible to fully align the project to the LCD screen image so you dont get that blur you showed, but with the OBS middle man any reboot of the PC running this setup, I can't see a way to say launch plex, launch OBS, and OBS full screen preview so it "just works"

@adityav OBS has a "full screen preview" option. I assume that's what he used.  record display output connected to LCD and setup the full screen preview to show on the projector.

Updated the main post to answer some of the questions that have been posed.

@CurlCascade I wish I'd thought of that layout... that would work nicely.

I have several donor TVs I'd love to try this with!

This would be great to use in an interactive table display, like the ReacTable or the original MS Surface concept, assuming the touch interaction system could be worked out. The projector and light-path-folding mirrors could be contained within the base.

I know 40-plus-inch capacitive touch monitors exist, but finding one – even one with a bad backlight – for a reasonable price seems very unlikely. I'm sure the FTIR technology would not work with this (although I'd be happy to be proven wrong).

I wonder if the ITO electrodes inside a disassembled (and cleaned) LCD panel could be repurposed as a cap. touch panel 🤔

I'm also a little concerned about the parallax effect, being so close to the display. Maybe a thinner diffuser could be found.

@curlcascade Wouldn't this require curved mirrors?

@diyperks

What model of tv did you use, what are the resuirements for a tv to be able to be used like this?
How is the delay between the projector and the LCD panel? Is this configurable in software so that they match perfectly to avoid ghosting?
Would a edge lit backlight tv also work?

First of all, amazingggg project! You are an inspiration. 

Secondly :), how can I process the image coming from an AppleTV? I guess I use an HDMI splitter to send one to the TV and one to the projector?

But how can I process the image coming into the projector? Maybe like a raspberry PI with OBS installed that filters real time? Or could the projector with contrast and other inbuilt settings reach the same effect? 

Instead of OBS would it not be possible to simply duplicate the display output onto the projector? I need OBS free to record things and having no screen during startup and shutdown (if I'm interpreting correctly) is a bit of a deal breaker. How does this setup interact with HDR and VRR? I don't use HDR much but I really don't want to go back to not having it and VRR has become an almost daily use feature of my display.

What model of tv did you use, what are the resuirements for a tv to be able to be used like this?
How is the delay between the projector and the LCD panel? Is this configurable in software so that they match perfectly to avoid ghosting?
Would a edge lit backlight tv also work?

@adamkafei use streamlabs for one of the tasks, its the exact same thing

@curlcascade

I was thinking something similar. using a oneway mirror this could be made into something with a similar rootprint as a rear projection tv. With this there would be room for activities like a ballin soundsystem.

@j3roen16 That's a neat suggestion but unfortunately that only works on Windows. U was thinking of possibly duplicating the display output and then setting up the projector to have zero colour. The only thing is if there's no means to means to replicate the glow effect in hardware, that said, don't projectors have focusing rings like cameras do? Couldn't that do the job?

can this work with any tv of any resolution?

will the refresh rate also be good?

Would like to see portability added to this idea, to set up large movie screens outdoors, like at a park. Like, maybe the use of flexible LCD panels, to eliminate the risk of breaking the panels.

I would love to see a part of the initial post with a "BOM" type section. I am not super educated on the differences of the types of tvs talked about, or the projectors talked about. what exactly do i need to look for in the tv and projector? 

You would need an elderly (and usually cheap) LED backlit TV which is most of them. A few (and I've only encountered these in old laptops) use fluorescent lamps. But either should work. Plasma TVs are not suitable.

Matt used a DLP projector for this but I suspect any projector (LCD/DLP) would work as it's only producing the light (luminance) map.

A very clever idea and I salute Matt's ingenuity (and yes, I know, I need to stop being such a mule kisser).

Honestly would be interesting to put a DLP system into a rear-projection TV. Those already have the optics inside and typically have decent speakers. The extra space inside could house an image processor to automatically do the effects and you could use it like any other TV. 

Many RP TVs used DLP and they aren't really any better. The problem is not so much that those tiny LCD displays are poor, its that projection isn't as precise as the LCD panel. Optics isn't my strong suit but I expect it has a lot to do with the rear-projection scattering the light sightly. Home DLPs only use a single chip, the ones used in commercial cinema projectors have a chip for each colour so they are much brighter and produce more, richer colours.

It's curious to note that if you watch movies shot in the pre-CGI age that make use of rear-projection effects (James Cameron used the technique in Terminator where the truck explodes and in Aliens when the drop-ship crashes on the LV-426.

When seen on cinema projectors of the day the blend was almost seamless but viewed on a modern TV from a re-mastered film even on an LCD screen, you can see the actors are brighter and don't match the background which undermines the effect.

Matt's idea here marries the screen sharpness of and LCD colour image with the brightness map from the projector. It's quite brilliant if a little impractical in its current form. Matt's right I suspect that that a "short throw" projector would be more compact.

Hello there,

Is there a way to upgrade an old projector by modding its original hardware or replace parts of it? I have an old projector that operates with a traditional light bulb, and I was wondering whether it would be possible to enhance its performance by converting it to LED and applying other modifications.
thanks!

super interesting video! got me thinking about backlight strobing in LCD monitors now that attempt to mimic the same thing CRT's do with persistence of vision. I wonder if you could put a crt directly behind the lcd layer of a newer monitor? get best of both worlds with LCD sharpness but CRT persistence of vision.. i imagine too you could do this all the way up to 240hz+ by turning down the resolution on the CRT (broader dimming zones) in exchange for higher refresh rate. would also be a good use of black and white crts! although i wonder if the image would be bright enough particularly with ageing tubes. I imagine the hardest part by far would be syncing the two up fully since they run off different connections and have different input lag levels.. if i had the means and prowess to try this myself i would love to see what it would look like. (apologies if any of my understanding is wrong ^)

@johnygabriel The electronics to drive one of those projector bulbs is a little more exotic than a simple DC source but I've certainly seen it done. As I recall there's a least one video on YouTube from someone who's done exactly that, might be worth a look.

@bianca-b CRTs are more about persistence of the phosphor dots than human persistence of vision, that's why you don't see many CRTs with very fast displays due to limitations in how rapidly the charge runs away from the dot. Long persistence times were a factor in older oscilloscopes. LCD dots (and especially OLEDs) can switch on and off in nanoseconds so we can make larger, faster displays that the old CRTs can only dream of.