Barco LS4K

[Fernando Caldeira]

Hello all,

Has anyone seen or worked with the new Barco HDR LS4K-P?
Is it as good as they say it is?
Is there a contrast ratio number out?

Thanks
Fernando

[Leo Enticknap]

I saw it on display, and a demo of it working, at Cinemacon earlier this year.

The demo I saw was of a restoration of Godzilla vs. Mechagodzilla: 1970s dye-coupler color, no matter how well captured and post-processed, is not going to put any ultra-high contrast display technology through its paces, so I didn't get an objective sense of how much of an improvement it is on the 1.38" chip SP4Ks with a high contrast lens in front. Subjectively, it looked very good to me, but I'd need to have seen the same movie projected from, say, an SP4K-27BHC, to have any idea of whether it's a significant upgrade from it.

[Steve Guttag]

I'd think any contrast ratio that they could publish will need to have an asterisk with it. Contrast Ratio for DCinema has had to be one of two numbers. The feel-good number is to project full white, measure...then project full black, measure. The light is not allowed to be modulated. These are the CRs that get you from 1600-6000:1 (sequential contrast). The real contrast ratio would ANSI contrast and those are much worse...in the 100s:1 ANSI CR uses a 50% checkerboard pattern. You measure the center white square...then flip the squares black for white and measure again...so the entire optical system is excited and you have plenty of light scattering about (it also will let the room itself, and its light reflections, degrade the measurement).

Light Steering takes advantage of the fact that rarely does the entire image need to be full bright (and if it is, there aren't darks to compare and your eye's iris will shut down to not resolve the darks being blown out). So, if we can recapture light that would, ordinarily, need to be reflected to the heat sink for the dark portions and redirect it to the lighter portions we can have brighter whites while keeping darker darks. If you were to run an ANSI Contrast test, it is going to test similar to any other high contrast projector because with a 50% checkerboard pattern it doesn't get to reclaim anything.

I think they're going to have to have some sort of qualifier to put up whatever number they associate with it as it will be equivalent to. Mind you, home theatre projectors have been modulating their light for years to get their fanciful claims of a gazillion to 1 contrast ratios. The same way DCPs have to have a frame of image data for every frame of video, we also don't get to modulate our light.

My personal opinions are, if you watch content on a projector that has about 3000:1 CR (sequential) and one that has 5000-6000:1, are you not going to notice much difference. If I were to set up two theatres, one with each and you could walk between the two to watch the same content, you'd be hard pressed to say which was witch. With an A-B in the same room with zero or near zero delay between comparisons, you will see it but the real world isn't like that. People just don't notice things getting that much darker, after a point until you finally make it from dark-grey to black.

The other aspect of the Light Steering projector is that it is going for 300nits or about 87.5fL. This, dramatically improves contrast ratio on its own. With a 48nit (14fL) white level, you've see up a tough contrast ratio. To get 2000:1 with 14fL, you need to get your dark level down to .007! How good is your meter to measure that one? Even at 87.5fL, you are only up to .044fL with a 2000:1 CR. So, getting a projector that has an optical path that can get up to 5000-6000:1 before any sort of light manipulation is going to go a long way to having the darks remain dark at the elevated level.

Personally, think that going for 300Nits, at this stage, is the wrong move. In order to get the white level up that high they have to severely limit the screen size so it will not be in your biggest theatres. Had they gone for a more modest 108Nits (Dolby Vision), the same technology could be used in large theatres and with a growing content list of movies mastered with that sort of white point.

In the end, they won't be able to touch emissive screens (LED) because their off is 0 and their on is whatever the LED is capable of. So, a real 300Nits with a contrast ratio that is limited by the ambient lighting of the auditorium, not the light source. That is where you will see HDR get mainstream in cinemas. The question is when the technology will be affordable enough to support the purchase combined with the movie industry's behavior to theatrical attendance.

[Stefan Scholz]

It is all about specs on paper.
Projection has limits, and no projection will be capable of true High dynamic range images.
The re-reflections from the room limit your contrast ratio. It eventually is possible to design a matt black room, with matt black seating, and being alone in that room as a measurement engineer, switched off emergency lighting, you might read a decent contrast value.
The moment the lights are turned on, the measured contrast diminishes. Then, a stadium full of patrons, each with a glossy, reflective face, the re-reflections limit your contrast significantly. A floor curve of old school rooms helps, but is rarely found.
The main reason I see for raising light levels on screen is in the fact, that 50 nits (cd/m2) or in imperial units 14 fl, is on the border of night vision for most humans. Meaning limited color rendition. All cats are grey at night. Just going above that, does really help to make movies look great. I doubt 300 nits or 87.5 fl will bring the great wow effect. It's brighter.
Another factor of human vision is the limited range of contrast perception within a given state of accomodation to light. Our eyes adopt to the current brightness level by trimming the iris. Still the receptors have the same limited range they can capture. The dynamic range of a computer monitor is higher, than the range our viewing mechanism can resolve.
Still, in projection there is a need for great native machine contrast, the very limited dark capabilities of early generation digital projectors have never been acceptable. I have found Kinotone brand Barco based 4K projectors, where we were able to measure an actual contrast ratio in checkerboard patters below 40:1, it might have even been 25:1. The machine was sold like this, complaints made, but nothing happened.
The moment the warranty period was due, the manufacturer service had a hint "about too low contrast", but also knew "out of warranty".
This has not been the only projector with such a problem I found in the field, but the one I measured due to curiosity.
With Barco made ones, the images always looked better, still early 4K never really had satisfactory contrast on any manufacturer.
Today I always aim for the Ultra High Contrast lens option on the 4K projectors, these also offer a better overall visible "convergence" and resolution over High Brightness or Enhanced Contrast versions of the lens. Pair it with 75/ 80 nits/ 25 - 27 fl on screen (the upper value of the old film standard for 35 mm), and there's a significant benefit perceived and noticed over competing venues in the market field.

The Dolby Vision approach seems to be a good compromise, in well designed rooms. Full color rendition for the viewing mechanism, large enough screens possible.
Their illumination brightness seems to recreate the initial brightness standard for 70 mm roadshow in the 1960's.