Film-Tech Forum ARCHIVE: How do they convert film to Blu Ray

This is topic How do they convert film to Blu Ray in forum The Afterlife at Film-Tech Forum ARCHIVE.

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Posted by Louis Belloisy (Member # 3836) on 12-30-2008, 07:45 PM:

I really cant find a good answer to this and inquiring minds need to know. I assume they scan the film to digital, but as far as i can see, the detail that blu ray shows is not on the film. and if they are scanning at such a high res, why doesn't the film grain show, especially in the black and white conversions. thanks in advance for the class in conversion 101.

louis

Posted by Mark Gulbrandsen (Member # 72) on 12-30-2008, 08:29 PM:

quote: Louis Belloisy
why doesn't the film grain show

The film grain should show if the transfer is done right and your viewing system can resolve it(1080P). Mine can and I can see it in many releases. Its also easy to tell when they change film stocks by the change in grain size.

Mark

Posted by Paul Mayer (Member # 355) on 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.

Posted by Louis Belloisy (Member # 3836) on 12-30-2008, 09:13 PM:

Hello Paul and Mark.

Paul thanks for the detailed explaination in the link to one of your prevous posts. Makes it a little clearer now.

louis

Posted by Scott Norwood (Member # 30) on 12-30-2008, 10:29 PM:

As for the "more detail" issue, it's probably a combination of a transfer done from a higher-quality element than a typical release print (e.g. an interpositive made from the camera negative) and some additional over-sharpening/edge-enhancement done either as part of the transfer or as part of the disk authoring procedure.

In principle, the soundtrack can be better than analog or digital sound on a 35mm release print, since it can be recorded at a higher bit rate than DTS/SRD/SDDS directly from the original mag track or digital tape, assuming that such elements exist.

Apparently, many Blu-Ray transfers have been "de-grained" to make the image appear sharper. I have no idea why, except that perhaps grain does not work well with the HD aesthetic. It probably also does not compress well.

I haven't seen a high-end transfer setup since the late 1990s, when everyone was using Rank or Bosch flying-spot systems and recording directly to tape. Do the modern systems work in the same way, or are new transfers done by scanning individual frames (as with a DI)?

Posted by Bobby Henderson (Member # 840) on 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.

Posted by Stephen Furley (Member # 1277) on 12-31-2008, 07:24 AM:

Grain is a problem for compression systems due to its random nature; because it changes from frame to frame it is a particular problem for formats which use temporal, in addition to spatial compression, such as MPEG-2 and H264, so excessive grain reduction is sometimes applied to material to be compressed in these formats. Digital cinema does not use temporal compression does not use temporal compression.

Posted by Bobby Henderson (Member # 840) on 12-31-2008, 11:23 AM:

JPEG2000 digital cinema files have a big advantage over the formats used on Blu-ray in that every movie frame is a separate, discrete image. MPEG-4 AVC and Microsoft VC1 formats use increasing levels of inter-frame compression as bit rates get lower.

It takes a lot more bits to lossy compress an image with a great deal of grain or noise in it than it does to compress a similar image with a smoother appearance. That holds true regardless of whether you're working with a still image or a video stream.

Posted by Blaine Young (Member # 3992) on 12-31-2008, 01:13 PM:

This is why the MPEG2 system used on DVD was so crappy. Things like fog and fine wood-grain look like they've been possessed by nanobots. To properly render these images, the bit-rate has to be jacked up higher than DVD can sustain.

Blu-Ray isn't perfect, and a poorly mastered title can still look like complete shit (the aforementioned first release of "The Fifth Element), but at almost any level, BD is far superior to DVD.

The grain problem is one that has been plaguing the studios. The vast majority of the public don't understand what grain is, why it is and that in some cases it's _supposed_ to be there. And then studio efforts to remove it has caused the unwanted side effect of removing some of the image details.

Posted by Monte L Fullmer (Member # 2797) on 01-01-2009, 05:15 PM:

Reading the topics that our good friend, the "late" John Pytlak replied on emulsion layering and the reasons in that link that was posted by Paul, makes perfect sense, in as well as very educational reading on this present topic of eventual duplication from film to recorded media.

Posted by Steve Guttag (Member # 268) on 01-01-2009, 07:30 PM:

I just figured they were using Blu-Ray cameras pointing at the movie screen in select theatres...naturally a DCinema theatre would be the preferred sourced for a Blu-Ray bootleg!

Posted by Monte L Fullmer (Member # 2797) on 01-02-2009, 12:54 AM:

That's a horrible thought - since the hertz rate from the image would be the same as the video rate...is that true?

Posted by Bobby Henderson (Member # 840) on 01-02-2009, 10:57 AM:

If a video camera capable of recording in 24fps mode is used it could capture a flicker free image of the screen. But why even bother going to the theater? You can author the new Blu-ray simply by pulling segments of it off YouTube. After all, the Flash Video on YouTube is digital, and because it is digital that means it is perfect!