Film-Tech Forum ARCHIVE: 2K DCPs vs 4K DCPs DVDOMATIC vs...

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Posted by Kirk Futrell (Member # 5006) on 09-26-2013, 10:53 AM:

So I have recently had an occurrence of 2 different rentals where they wanted to show a 4K DCP that they had created with Open DCP. We have a Doremi 2k4 and a barco 4k-23b. Both claimed to use an exclusively 4K work flow from filming to editing to finalized file. But just for grins they also made the same file using DVD-O-MATIC. DVD-o-Matic does not support 4K but will down scale the files to a 2K resolution. When we watched both films no one could tell a bit of difference between these two files on our 4K projector. What do you think is going on here. How do I know if my projector is actually playing 4K? If I play a 4K test pattern it will be bigger than the imager, correct? So I would see a cropped version, I think. That is not happening 4K resolution files look fine. But even up close I can't tell the difference between a 4K source file at 2K vs. a 4K file at 4K.

....That being said I can definitely tell a big difference between a 2K projector vs. a 4K projector. I watched Pacific Rim in 3D 2K edgeblend fake IMAX at a regal where I felt like I could almost reach out and touch the 2K pixels and I was not impressed, I'm spoiled by our 4K.

So the question remains, why do the two files look the same to all involved?

Posted by Dave Macaulay (Member # 813) on 09-26-2013, 11:54 AM:

Check in the Doremi license manager and confirm you have a 4K license.

Posted by Marco Giustini (Member # 4544) on 09-26-2013, 05:41 PM:

4K and 2K are handled by the server/projector, you won't see cropped or scaled picture on a DC system.

Posted by Manny Knowles (Member # 1171) on 09-28-2013, 11:37 PM:

How big is your screen?

Posted by Kirk Futrell (Member # 5006) on 09-29-2013, 05:20 PM:

The Doremi says I have the 4k licenses. The screen is 30ft. But I don't think that matters when I am standing 10 ft. away.

Posted by Dave Macaulay (Member # 813) on 09-30-2013, 12:43 PM:

You should see a difference between 2K and 4K content. Try downloading some guaranteed 4K content. The doremitechno.org ftp site has a 4K trailer and the RED camera 4K demo reel - but not 2K versions for a direct comparo.
Showing patterns works properly, presumably. The 4K convergence pattern has single pixel lines, for example.
If known 4K content looks "4K" but your content looks the same exactly between 2K and 4K versions - something was done with it at 2K during production and there is no real 4K in the 4K version. Because of the x4 image data raw size and the capabilities of JPEG2000 compression, a 2K clip rendered in 4K will have larger image data files than the 2K version although there is not more "real" image data there.

Posted by Kirk Futrell (Member # 5006) on 10-02-2013, 11:26 AM:

Thanks for the follow up, Dave. I may download those files but as you mentioned since there is no 2K version I can't really do a side by side.
We did a 4K series and the DCPs looked fantastic. We showed Lawrence of Arabia, Samsara, Heaven's gate among others. They all looked fantastic and you can easily see the film grain instead of pixels. But nearly everything we play on that projector looks great from 4K to Blu-Ray. I know the Barco is 4K as the 4K convergence tests look right not that I ever suspected the light engine was 2K. I just can't seem to get my hands on anything that is 2K and 4K and do a "A", "B" test of the same source material. I may have to go get a Blu-Ray of a 4K we are showing so I can do a comparison that way, and look for ailiasing.

Posted by Dave Macaulay (Member # 813) on 10-02-2013, 11:33 AM:

I would recommend anyone with a 4K system to have a look at the RED demo. This was (obviously...) made to show off their 4K camera and the production quality is pretty amazing. I've seen it on both 2K and 4K systems, and the detail difference in 4K is quite noticeable - particularly in peoples' hair.