How are film masters scaled to UHD bluray - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 4 Old 03-14-2019, 04:21 PM - Thread Starter
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How are film masters scaled to UHD bluray

Say you have a 4096 x 1716 film master. It seems to me that the best way to release said content on a 3840 x 2160 bluray would be by cropping 256 pixels horizontally and adding letterboxes vertically. UHD blurays don't come in 3840x1716 (2.24:1) resolution so they are obviously doing something else.

Also what is the purpose of 4096x2160 projectors when there isn't even content available to them. To take advantage of the extra horizontal space, you will have to scale the image so that the pixels are no longer 1:1 with the blu-ray source
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post #2 of 4 Old 03-15-2019, 04:35 AM
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Originally Posted by olqxqipz View Post
Say you have a 4096 x 1716 film master. It seems to me that the best way to release said content on a 3840 x 2160 bluray would be by cropping 256 pixels horizontally and adding letterboxes vertically. UHD blurays don't come in 3840x1716 (2.24:1) resolution so they are obviously doing something else.

Also what is the purpose of 4096x2160 projectors when there isn't even content available to them. To take advantage of the extra horizontal space, you will have to scale the image so that the pixels are no longer 1:1 with the blu-ray source
Have you heard of the concept of "safe" in filming? Action-safe, title-safe, broadcast-safe, etc. Basically, movies and TV are shot with extra padding, as it were, to allow for distribution/broadcast in a variety of aspect ratios. Likewise, it's also very useful in editing just in case a boom mic drops into frame or you want to digitally pan/shake/zoom. So cropping the sides (pillarboxing) or the top and bottom (letterboxing) are possible without losing anything important. Between cropping and scaling (up or down), there's a lot of flexibility there to deliver very specific specs to each release, whether the target is theatrical, home video, trailers, streaming...

Keep in mind that Hollywood-industry scaling techniques using the raw master files (12-bit+ 4:4:4) are much more sophisticated than what comes on our televisions, so a studio can achieve very good results if the AR is fixed due to artistic reasons. Likewise, displays with native 4096 can scale the image up (usually with some loss in detail) or it can simply display 1:1 and you'll get a narrow black mask around the whole image.
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post #3 of 4 Old 03-17-2019, 10:17 AM
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It depends on the film, its aspect ratio, and who is doing the transfer.


I had an opportunity to compare some Marvel movies from their DCP to the Blu-ray. One of the 2.35:1 films was simply cropped from theatrical 2K down to 1920x1080 for the Blu-ray. The Avengers was 1.85:1 on theatrical and the Blu-ray was expanded to 16:9. So the Blu-ray actually had more picture while the theatrical was cropped. I believe on the UHD they cropped it back to 1.85:1 again.

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post #4 of 4 Old 03-18-2019, 10:19 PM
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Originally Posted by bryantc View Post
It depends on the film, its aspect ratio, and who is doing the transfer.


I had an opportunity to compare some Marvel movies from their DCP to the Blu-ray. One of the 2.35:1 films was simply cropped from theatrical 2K down to 1920x1080 for the Blu-ray. The Avengers was 1.85:1 on theatrical and the Blu-ray was expanded to 16:9. So the Blu-ray actually had more picture while the theatrical was cropped. I believe on the UHD they cropped it back to 1.85:1 again.
I don't understand why in the case of the Blu-ray being opened up to 16:9 as to why that's acceptable. I want to see the ratio displayed at the theatre also on the home presentation. To me, anything other than the OAR is non theatrical.

Movies must be OAR, sports and movies must also have 5.1 audio, No EE or NO SALE!
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