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Rate PQ of Blus Scanned at 8k?

post #1 of 7
9/10/09 at 1:12am
Thread Starter 
The only ones I know of are

Baraka
Gladiator
Wizard of Oz
North by Northwest

I don't own any of these, but I read that good quality scanning is a major step in getting a great image on blu ray that doesn't need a much noise reduction, because the grain is finer. I'm just beginning to understand the process of transferring film to blu ray, so please correct me if I'm wrong.

Please help me compile a list of 8k scanned Blus that also managed to negotiate the rest of the process with good picture quality, with hopefully some grain retained, so the benefit of the 8k scan can be appreciated by a layman like me.

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post #2 of 7
9/10/09 at 5:34am
I'm surprised you mentioned Gladiator in the list, since there are extensive threads in this and other forums on how poor the picture quality is--excessive DNR and EE, etc.  Where did you read that it's an 8k scan?  If that's true, it certainly shows that 8k is NO guarantee of good picture quality.
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post #3 of 7
9/10/09 at 8:37am
Thread Starter 
Just google Gladiator and "8k scan" and you'll see what I read.

The point about 8k scanning is, I think, that DNR need not be used; but that doesn't stop paranoid execs from thinking: jeez, I can still see some grain, I want it to look like Toy Story. 8k scanning, as far as I understand it, is only one part of the process; so yes it can still be screwed up after that. But Gladiator is no proof that 8k scanning is a bad thing; if what I read was right.
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post #4 of 7
9/10/09 at 9:25am
I have only a rudimentary understanding of how film is transferred to video, so I'm sure that the more knowledgeable HTFers will be able to clarify the point, but I don't understand how an 8k scan could improve the picture quality of a Blu-ray disc.  An 8k scan has greater resolution than a 4k or 2k scan, and can resolve finer details, but it's ultimately going to be down-scaled to 1080p for the Blu-ray, during which process those details will be lost.

I feel like I must be missing something, though, because an 8k scan is considered a real plus for a Blu-ray disc release.  Can anyone tell me what I'm missing?
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post #5 of 7
9/11/09 at 12:40am
Thread Starter 
Quote:
Originally Posted by cafink View Post

I have only a rudimentary understanding of how film is transferred to video, so I'm sure that the more knowledgeable HTFers will be able to clarify the point, but I don't understand how an 8k scan could improve the picture quality of a Blu-ray disc.  An 8k scan has greater resolution than a 4k or 2k scan, and can resolve finer details, but it's ultimately going to be down-scaled to 1080p for the Blu-ray, during which process those details will be lost.

I feel like I must be missing something, though, because an 8k scan is considered a real plus for a Blu-ray disc release.  Can anyone tell me what I'm missing?
 

+1
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post #6 of 7
9/11/09 at 10:17am
One approach to it is, if you are doing any post-work, such as noise-reduction, color grading, and the like, it is potentially "cleaner" -- there'll always be some math noise and quantization error here and there.  But if you're working at 8k lines, with 14bits/color, do all of the math, and then down-sample to 10bit/2k lines (close enough,) then your high frequency error will be low-passed out. 

Think about digital audio -- if you sample at 44.1kHz, you can technically resolve 22.05kHz audio.  But the upper portions are going to be noisy because of math and rounding errors.  But if you sample and do the math at, say, 88.2kHz, and more bits, then you can also take that into account when you do the down-sample, and pre-filter in such a way you don't get audible (or, in the questioned example) visible math errors.

Of course, once that's done, it gets slammed into a AVC or VC1 or MPEG compressor.  But the thing is, the compressor won't be fooled by the math errors, either (which is probably one of the easiest ways of having visible "math errors" -- getting it enhanced by the compressor.)

It's not all smoke-and-mirrors, but technically, if done right, it can help the end result.

But then, it also depends on the telecine.  If it's a lousy 8k scanner, you'd be better off with a good 4k scanner.

Leo
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post #7 of 7
9/11/09 at 10:58am


Quote:
Originally Posted by Leo Kerr View Post

One approach to it is, if you are doing any post-work, such as noise-reduction, color grading, and the like, it is potentially "cleaner" -- there'll always be some math noise and quantization error here and there.  But if you're working at 8k lines, with 14bits/color, do all of the math, and then down-sample to 10bit/2k lines (close enough,) then your high frequency error will be low-passed out. 
 

This is indeed something I had not considered.  Thank you for the explanation.
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