Film-Tech Forum ARCHIVE: Question about 4k

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Posted by Geoffrey Hudson (Member # 7456) on 08-08-2017, 02:59 PM:

Hello.
Our theater has a Barco DP2K-10S projector with a Doremi IMS1000.

We are looking into being able to show 4K material, either from DCP or UltraHD discs through one of the external inputs.

I am wondering how hard it is to get there from here with this equipment or if that is even possible.

Posted by Andrew Thomas (Member # 7000) on 08-08-2017, 03:31 PM:

It's a 2K projector, so you could show the content downscaled, but in native 4K.

Posted by Geoffrey Hudson (Member # 7456) on 08-08-2017, 03:39 PM:

Would there be any benefit in quality in doing that?

Posted by Jim Cassedy (Member # 4115) on 08-08-2017, 03:39 PM:

Your BARCO projector will handle 4K content just fine, but it will
automatically 'downscale' the image to 2K. Noooo problem!

Posted by Frank Cox (Member # 6258) on 08-08-2017, 03:51 PM:

If you're asking what I think you're asking, then the answer is no.

Playing 4k content on a 2k projector will give you approximately the same results as playing 2k content on the same projector.

There's nothing gained (that I know of) by playing 4k content on a 2k projector.

Posted by Carsten Kurz (Member # 5396) on 08-08-2017, 05:29 PM:

4k DCPs will play on that system as a 2k DCP. The IMS1000 is not able to play UHD content in 4k, it doesn't feature the necessary HDMI 2.0 input. Content will be downscaled to 1080p to be compatible with HDMI 1.4a.
That HDMI 1.4a input is 4k capable, but only up to 30fps, and it lacks the HDMI 2.0/HDCP2.2 capability needed for UHD. Even if you feed a compatible 4k signal to it, it will be downscaled to 2k, just as with the DCPs.

- Carsten

Posted by Jim Cassedy (Member # 4115) on 08-08-2017, 06:39 PM:

quote: Frank Cox
There's nothing gained (that I know of) by playing 4k content on a 2k projector.

Well, I guess nothing other than the fact that you've saved a crapload of money
on not buying a 4K projector. LoL [Razz]

(note- - file this reply under: 'sarcasm')

Posted by Leo Enticknap (Member # 534) on 08-08-2017, 10:03 PM:

quote: Jim Cassedy
Your BARCO projector will handle 4K content just fine, but it will automatically 'downscale' the image to 2K. Noooo problem!

I can't now remember how I learned this or where, but as I understand it, the JPEG 2000 file structure within the image MXF file(s) in a DCP is such that all DCPs contain the core 2K image data, but 4K DCPs contain extra image data to "fill in the dots," if you will, to complete the 4K frame. The ICP and light engine of a 4K projector playing a 4K DCP will use both sets of data to wiggle the DMD mirrors, but in a 2K projector playing a 4K DCP, the extra "2K to 4K" image data is simply ignored.

So no downscaling takes place when a 2K projector is playing a 4K DCP: the extra 4K image data is ignored, and only the 2K core image data is read and processed.

I'm guessing that this stripping out happens in the server, media block or IMB: in the config setup scripts for most if not all the models I've encountered, you are required to state whether the projector is 2K or 4K.

Posted by Marcel Birgelen (Member # 6801) on 08-09-2017, 01:06 AM:

quote: Geoffrey Hudson
We are looking into being able to show 4K material, either from DCP or UltraHD discs through one of the external inputs.

I guess you're running a normal cinema operation and regularly play DCPs from common distributors.

In that case, you probably have already played a whole bunch of 4K DCPs without even really noticing.

Obviously, as others have pointed out, your equipment isn't capable of rendering 4K resolutions, simply because the light engine is stuck at a 2K resolution. Like Leo mentioned, the "rendering engine" in your IMS will only extract the "2K part" of the image from the DCP, even though the DCP itself is a 4K DCP.

If you connect a UHD capable Blu-Ray player, it will downscale it to FullHD, because like Carsten already mentioned, the IMS doesn't have the necessary HDMI 2.0 port and will also not handle the required HDCP level.

So, in order to do proper 4K, you have to upgrade your equipment.

Posted by Monte L Fullmer (Member # 2797) on 08-09-2017, 02:59 AM:

Thing one really has to watch out for is when the cinema owners are advertising features and saying that the presentation is in 4k when your equipment only displays 2k.

One hears a lot of this, but usually in reverse if the cinema advertises features shown in 4k when the feature is only in 2k, and they do have 4k equipment..like "projection from SONY 4K projectors.."

Bottom line is that only a spattering of features at present, are scanned in 4k resolution.

It's still a 2k world out there.

Posted by Steve Guttag (Member # 268) on 08-09-2017, 05:30 AM:

Leo,

A projector will downscale a 4K image to 2K (done in the ICP or equivalent). A SERVER will extract the 2K core from a 4K DCP. So, in this case, the IMS1000 delivers a 2K image to the projector and the projector is unaware that it started 4K.

Posted by Bobby Henderson (Member # 840) on 08-09-2017, 09:13 AM:

Most people really don't properly understand concepts of resolution. They don't understand the relationship of native resolution between hardware (projector, HDTV, etc) and software (video file stored in a DCP, Blu-ray, etc.). In order to have true 4K both the hardware and software must match or even exceed that 4K level. Of course you'll get the best looking results from a pixel for pixel match of hardware and software.

There are people buying Ultra-HD Blu-ray players and attaching them to their old 1080p HDTV sets, thinking that new player will make their TV "4K." But not to worry: most of the titles being sold on Ultra-HD Blu-ray were up-scaled from 2K sources. So it's mostly bullshit anyway. "How's that new HDR video looking on that 10 year old TV set, Cletus?" The movie studios couldn't give a shit about the misunderstanding; they'll happily take advantage by screwing the customer with a fake product. But then most of the general public doesn't give a shit about movies on disc anymore either. Notice all the shuttered video stores lately.

Doing graphics work I run into the problem of people not understanding resolution on a regular basis. It's really common when trying to help customers create graphics or video content for LED signs. LED boards can be configured in many different shapes, sizes and resolution/pixel-pitch levels (according to how much the customer can spend). It's difficult to get customers to take the right steps in tailoring their content to work on those displays. They'll go shoot a video with their phone or even a pro setup and then expect the sign to play the video just like a TV screen. They don't consider how the sign may crop the video or how its thousands of pixels won't be able to render all the 2.2 million pixels of detail in the video. Their complex video or group photo gets turned into unintelligible soup when down-sampled to their little 48 pixel tall by 128 pixel wide LED sign. All I can do is tell them "the more simple you make the image the better." I've even run into other graphics people who don't have a proper grasp of the concept. "How many DPI should I make this JPEG?" Ugh.

When customers ask what kind of logo files they should send for a project my response usually goes over the head. "What's vector art? What's resolution independent or scalable mean?"

Posted by Jordi Aguila (Member # 9875) on 08-09-2017, 10:37 AM:

Do you know if there are any veeeery old server that can not be able to reproduce a 4K DCP?

We're going to do a big delivery in DCP 4K and we want to be sure that 4K is accepted by all servers.

Thank you.

Posted by Carsten Kurz (Member # 5396) on 08-09-2017, 12:07 PM:

I don't know any strict DCI compliant servers that can not play 4k J2K.

Some 'DCI compatible' players in some areas of the world (e.g. beefed up E-Cinema servers with J2K capability), or some software players that may run on a festival may fail on 4k. But I wouldn't call these cinema servers. There have been quite a few 4k-only mainstream releases, so, if 4k would be an issue, they wouldn't do that. And I never heard that there were issues with these releases. the 4k compatibility layer was in the specs very early on, and every manufacturer of J2K capable DCI servers knew this and built them to that spec.

- Carsten

Posted by Leo Enticknap (Member # 534) on 08-09-2017, 11:27 PM:

quote: Steve Guttag
A projector will downscale a 4K image to 2K (done in the ICP or equivalent). A SERVER will extract the 2K core from a 4K DCP. So, in this case, the IMS1000 delivers a 2K image to the projector and the projector is unaware that it started 4K.

Thanks - that makes sense. Hence the reason why, when running the config script of a server that is being used in a Series 2 system with an IMB, you have to specify whether the projector is 2K or 4K. If you specify 2K, only the core 2K image is sent through the backplane to the ICP; but if you specify 4K, the extra image data goes as well. If you misconfigure (specify that the projector is 4K whereas in fact it's only 2K), then downscaling will be done in the ICP.

Posted by Tom Bert (Member # 5719) on 08-10-2017, 03:30 AM:

You should not mis-interpret the word "downscale" in this context. This is more correct:

quote: Leo Enticknap
in a 2K projector playing a 4K DCP, the extra "2K to 4K" image data is simply ignored.

Nowhere in the final result will there be a trace of the original -additional- 4K information: not squeezed, downscaled, or whatever

Posted by Steve Guttag (Member # 268) on 08-10-2017, 06:34 AM:

quote: Carsten Kurz
I don't know any strict DCI compliant servers that can not play 4k J2K.

It is the DCI spec that ALL servers and ALL projectors can play both 2K and 4K content.

DCI section 2.1.1.5 has the relevant verbage:

quote:
2.1.1.5. Hierarchical Image Structure
The DCDM shall use a hierarchical image structure that supports both 2K and 4K resolution files
(See Section 3.2.1 Image Concepts and Requirements so that studios can choose to deliver either
2K or 4K masters and both 2K and 4K projectors can be deployed and supported. The supported
mastering and projecting combinations are illustrated in Figure 3: Hierarchical Image Structure
Media Blocks (MB) for 2K projectors are required to be able to extract and display the 2Kresolution
component from the 2K/4K DCP file(s). Media Blocks for 4K projectors are required to
be able to output and display the full 4K DCDM. In the case of a 2K DCDM, the output of the
Media Block is a 2K image. It is the responsibility of the 4K projectors to up-sample the image.

So you are safe issuing 4K content to any DCP cable theatre in the world. However, the frame rate requirement was only to be 24fps for 4K. If you issue 4K at 25fps and higher, then NO not every server will be capable. Even for 2K, the requirement was only 24 and 48fps. (not up to 48 but just 24 and 48).

Posted by Jordi Aguila (Member # 9875) on 08-11-2017, 02:42 AM:

Thank you Steve, I think that you have replyed answer 100% my question.