A bit clickbait calling it "infinity contrast" even if it's higher contrast than an LCD, is it still a finite contrast. Probably not higher contrast than modern OLED TVs, but a clever hack with stuff at hand. Just not up to the hype of infinite.
Projectors are only "infinity contrast" in total darkness.
But with enough lamp power...
Larry Ellison used to have a TV projector sized for a movie theater but aimed at a home sized screen, so he could watch movies and enjoy a view of the outside world at the same time. Of course, now anybody can go to Costco and buy a TV that bright.
Projectors are never infinity contrast as they cannot turn off individual pixels. Projectors have a single constant light source to all pixels like a non local-array dimming TV. It's entirely up to the imaging panel to modulate the pixels, and none of the 3 panel types can block all the light for a pixel.
Laser beam scanning (LBS) projectors are, they genuinely don't beam any light to a black pixel.
Unfortunately they don't really exist commercially anymore. I hope the technology develops and they come back... in a way, they are to constant light source projectors what OLED is to LCD. They seem like the obvious evolution.
Yeah, but I don't think anything like that has ever existed at actually usable brightness levels for a large home theater size screen, or at a resolution at least 1080p.
> multiple projectors could be used to increase brightness.
Done in at least one early military large screen display system, using six CRTs (RGB x2) aimed at the screen. If one failed, the brightness dropped on the others but you still had an image.
The USAF put a huge amount of effort into early large-screen displays.[1] Not very successfully.
The most successful projection display before LCDs was the Eidophor. (1949-2000)[2] Big, expensive, complicated, high-maintenance, but reliable. Worked by distorting an oil film in vacuum with an electron beam. Biggest buyer was NASA's mission control center. In its final 1990s form, it was bright enough to be used in stadiums.[3]
The author is using a DLP projector to backlight the LCD. When the projector is displaying black it effectively is infinite contrast. The light is reflected away and never reaches the LCD to backlight it.
He also did not do (or at least did not mention) anything about the reflected/diffused and ambient light behind and around the TV screen, which would negatively impact contrast.
Aw, give him a break. Neither do OLED tv reviews, but I do not see everyone piling on them "well, technically the contrast isn't inf because the screen is scattering the ambient light"
Have you seen those samsung qdoleds? In a normally lit room they look more washed out than a VA panel, yet somehow still having an "inf" contrast...
That's not true at all. Black on a projector is still projected light, especially with a DLP which have the worst contrast ratios of the 3 projector types (DLP, LCD, LCoS).
What he is making here is a dual panel display. There are actually some LCD monitors that use this concept of 2 separate panel layers each providing their normal contrast resulting in a multiplicative effect.
For the video posted here, the DLP is probably at best 1000:1 and the cheap old LCD is also maybe about 1000:1, so you get about 1 million:1 which is a lot, but not technically infinite like self-emissive display that can turn off the pixels completely for sections of the picture like OLED and microLED.
> Black on a projector is still projected light, especially with a DLP which have the worst contrast ratios of the 3 projector types (DLP, LCD, LCoS).
If DLP has worst contrast than LCD, then why would this project be even remotely successful? Wouldn't the LCD layer in the stock LCD TV would have already been more effectively blocking the light from the stock backlight?
You're missing that the LCD is still there. It's still blocking just as much light as it originally did, but now the DLP chip is also blocking light. The effect stacks.
He has a different video where he makes such a screen, actually. I was kinda surprised when I saw this video pop up, thinking "Didn't he do this already?"
What makes self-emissive "technically infinite" but not DLP?
I would say the weak point of DLP is the screen material needing to be light-friendly, but that's on a sliding scale with the emissive display, not a hard line difference. Both of them preserve black levels when turning on, unlike traditional LCD, but also it isn't true black for either of them.
LCD projectors do better at contrast than DLP though.
For example the Epson 5050UB or LS12000 do about 5000:1 native contrast. Most DLPs around the same price level are in the 1000:1 to at most 2000:1 contrast level.
A DLP is nothing like an emissive display. The entire area of a projected image with any projector is always lit up by the light source. Any projector, including DLP is like a TV with a single backlight and no local array dimming.
Here are some simple photos of DLP projectors and here you will clearly see that the black parts, like the black bars above and below the cinemascope image, or even the spill over past the edges of the panel are not black at all.
In that second photo, the odd shape of the black projected area is due to the user using keystone, so the image is not being displayed on that part of the imaging panel and it's just left black, but you can see then what the black level really is for projected "black" pixels.
Mirrors aren't perfect. Some percent of the light will hit a microscopic deformation and scatter. You only need ~1 part in 1000 to scatter for it to ruin your contrast ratio.
The projector lens's optics (coatings, materials, etc.) will have been designed and engineered to have a specified contrast ratio.
So yes, if the internal light engine of the DLP truly reflected all light away,
then, if it outputs zero photons for full-screen black, you could say the projector outputs zero photons.
However, the DLP is not 100% effective; the interesting images will have a mix of bright and dark areas, and the lens and software image processing will raise the black levels above zero.
Source: I worked at BrightSide Technologies before and after the acquisition by Dolby Laboratories and learned about DLP lens limitations from the engineer working on DLP+LCD based HDR displays.
Ignoring the fact that the projector doesn't get to true black (noted by smusamashah), and supposing there's no diffusion that spreads the light of a pixel out to surrounding areas of the display panel, it would be possible to say that the display has infinite contrast, I suppose that is true.
Contrast is important, but alone it is useless. You could have a display with only two levels: black and white, and if the black is perfectly black, then it's infinite contrast (any level of white, no matter how dim, is infinitely brighter than total black), but 1-bit color would be useless in reality for home theater.
To make infinite contrast useful, it's necessary to have HDR as well to take advantage of having very dark and very bright areas both able to be represented with detail. Plus having sufficiently bright maximum brightness so that the brightest highlights can really shine.
> To make infinite contrast useful, it's necessary to have HDR as well to take advantage of having very dark and very bright areas both able to be represented with detail.
SDR benefits incredibly as well. HDR is another elevation.
Getting stuck with LCD contrast for years was a travesty to image quality across the board.
When I read infinity contrast, and knowing how great DIY perks is, I assumed it to be something like this https://youtu.be/JoLEIiza9Bc?t=335 but couldn't wrap my head around the idea on a TV.
the joke is that contrast is a ratio, and any number over zero* equals +inf. I've seen similar lines used in OLED advertisements during 2010s, despite many OLED having non-zero minimum intensity. It's a reference to those.
