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Topic: How do they convert film to Blu Ray
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Paul Mayer
Oh get out of it Melvin, before it pulls you under!
Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000
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posted 12-30-2008 08:47 PM
Here's a link to an old thread that describes the general process of doing film-to-digital video transfers. The example talks about standard definition, but the process is similar for high definition, with correspondingly higher quality standards applied (things you can get away with at SD don't look so good at HD - HD can be very revealing and unforgiving):
http://www.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=12;t=000477#000001
As for a Blu-ray transfer showing more detail than what is on the film (I'm assuming a typical 35mm 1.37, 1.85 or 2.39AR frame here), I find that hard to believe. A 1920x1080 image may be adequate for non-critical viewing, but even a 35mm frame cropped to 1.85AR can contain lots of information that will be lost at 1920x1080, especially if fine-grain film stock is being used.
Properly exposed fine-grain stock will show very little grain. Grain appearance can be either reduced or enhanced during the transfer depending on the desired look. Careful use of things like DVNR (Digital Video Noise Reduction), noise coring, shaping, and contouring, plus detail and/or edge enhancement can be used to shape what the grain will look like. And that's before trying any of the various computer-based tool suites currently available during post.
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Bobby Henderson
"Ask me about Trajan."
Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001
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posted 12-30-2008 11:37 PM
The best looking Blu-ray discs are derived from digital intermediates. Most DI-sourced Blu-ray movies come from 2K DI. Some come from 4K DI. And then you have some rare ones with DI work done partially in 6K or even entirely in 8K (Baraka).
A lot of early HD masters of movies were made via telecine systems that copied video off film prints in real time. Factor in what sort of elements were being copied -usually some sort of interpositive or internegative.
Modern DI work flows carefully scan the original camera negative, some direct copy of it or whatever best surviving element is available if we're talking about an old movie. The "color timing" work is handled in the digital realm. 35mm release prints, JPEG 2000 virtual prints, DVDs and Blu-ray discs are all sourced from those digital intermediate masters.
Old movies can be (and in a good number of cases have been) "digitally restored" using digital intermediate methods. The Searchers, The Godfather Trilogy, Bladerunner: The Final Cut and Close Encounters of the Third Kind are just a few classics treated using modern digital intermediate techniques.
Some, but not all, movies on Blu-ray have been treated with varying levels of "dynamic noise reduction" techniques. I really don't like DNR use because it destroys native detail in the digital image. It's a fancy method of blur that can ruin a lot of fine details. Skin textures, fine fabric weave, individual hairs and lots of other intricate surface detail can be turned waxy looking or merely erased through liberal use of DNR.
Movie studios often feel pressured to de-grain movies because they think most customers will dislike the natural grain in the image. Sadly, they're right for the most part. And that's because most movie buying customers don't understand the situation with that original film or video based image. Yes. There is often plenty of "grain" in video too. Apply some filters to reduce the red and green pixel noise coming up the shadows of a digital-sourced movie like The Lookout and you may kill a great deal of the lit up detail in that scene. Just leave the noise alone. But the studios can't since the customer is always right. So we get Blu-ray travesties like Patton or Gangs of New York.
I've heard people complain about the grainy look of the Blu-ray version of Close Encounters of the Third Kind. I think it looks very good. Sure, it's grainy looking. But I can still see a lot of sharp detail through that grain.
The biggest problem I see right now is movie studios recycling old HD telecine masters as Blu-ray source material and churning out discs just to get them on store shelves.
For example, Sony screwed the pooch with the first BD release of The Fifth Element. They used an old master sitting on the shelf. They encoded it in MPEG-2 and squished the bit rate enough to fit it on a BD-25 disc. That release was not well received at all. Sony made right on it by starting from scratch, creating a new film scan and HD master, doing an MPEG-4 AVC encode and putting the movie on a BD-50 with a generous bit rate. The 2nd version looks a hell of a lot better.
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