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Why is a "4k transfer" better than transfer from the film source?

17K views 5 replies 5 participants last post by  John Mason 
#1 ·
I'm seeing a lot of Blu-ray discs being advertised as being from a "4k transfer" or "Mastered in 4k" and I don't see how that's advantageous to transferring from the film source. Isn't the film the highest quality image available for such a transfer?

Apologies if this has been answered elsewhere. I'm just trying to sort out if this is hype or something substantive I should be looking for on new releases.
 
#2 ·
Movies shot on film are now scanned and mastered at 4K resolution. Movies shot with digital cinema cameras are often shot with cameras that have 4K or higher resolution. Older films that pre-date digital cinema are often scanned at 4K for remastering at 4K, so that they can be released in 4K cinemas and Ultra HD streaming and disc formats.
 
#3 ·
I'm seeing a lot of Blu-ray discs being advertised as being from a "4k transfer" or "Mastered in 4k" and I don't see how that's advantageous to transferring from the film source. Isn't the film the highest quality image available for such a transfer?

Apologies if this has been answered elsewhere. I'm just trying to sort out if this is hype or something substantive I should be looking for on new releases.
No one is saying it's better than the film source.

It just means the film elements were scanned at 4K resolution.
 
#4 ·
Thanks for the quick answers! Maybe I didn't phrase it as clearly as I could have. I'm thinking of films that predate digital cinema. Redistribution to 4k cinemas is pretty rare for old movies and unrelated to the packaging and marketing on Blu-ray releases.

Is there a benefit to the consumer by scanning the film at 4k then downsampling to 1080p for Blu-ray release, instead of just scanning at the desired 1080p output resolution to begin with, or is this a way of making consumers feel they're getting something better because "4k" was somehow involved in the process and that's a buzzword they might be looking for as an indicator of higher quality?
 
#6 · (Edited)
Thanks for the quick answers! Maybe I didn't phrase it as clearly as I could have. I'm thinking of films that predate digital cinema. Redistribution to 4k cinemas is pretty rare for old movies and unrelated to the packaging and marketing on Blu-ray releases.

Is there a benefit to the consumer by scanning the film at 4k then downsampling to 1080p for Blu-ray release, instead of just scanning at the desired 1080p output resolution to begin with, or is this a way of making consumers feel they're getting something better because "4k" was somehow involved in the process and that's a buzzword they might be looking for as an indicator of higher quality?
Some posts I made earlier this week relate to some of this. One has a link to a tech paper that outlines why 35mm film projection delivers on-screen images similar to 720p HD resolution. Scanning them to 4k or better offers the possibility of more detailed images--with the right delivery/playback hardware. Here's an avsforum post outlining how down-scaling 4k or other resolutions enhances a lower target resolution (like a Blu-ray). Upcoming UHD Rec.2020 Blu-rays can deliver the 4k scans to homes.


Virtually all movies made these days have a 2k master digital-intermediate resolution, regardless of any film-scan or digital-cinema camera resolution--which in theory can be up to 8k with Sony's F65 or in reality with a 65mm film scan such as "Baraka" (see last Milestone ). Make that, after this recent IMDB search , roughly 19,200 2ks, 1290 4ks, and 24 8ks.

I used a Blu-ray that started with a 4k D.I., "The Tree of Life," to measure effective or visible resolutions, comparing fine details to multiburst varying line widths last year . That's not to say similar maximum effective resolutions, like the fine details on a building's façade measured, couldn't be derived from a 2k-DI-based 1080p Blu-ray. -- John
 
#5 ·
Film can only be seen with a light projector on a big white screen. In order for it to be on a blu-ray disc it has to be digitally transfered somehow.


But the scan from the film cannot be put directly as it is on a blu-ray disc, it has to be digitally manipulated, compressed etc. and then put on a bluray disc.

That digital manipulation and compression of the original scan comes with a very minor loss in visual details, so its better to lose something from a 4k (bigger detail) scan on its way to 2k(1080p) , than to lose from the 2k scan that already lost details from the 35 mm film that has a natural organic 4k detail.


Similarly, 70 mm film has 8k details, so on a 4k blu-ray it will be preferable to scan the 70mm film at 8k (see Baraka documentary shot on 70 mm and scanned at 8k)
 
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