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2K scan vs. HD scan(1920x1080)


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#1 Tom Hepburn

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Posted 14 March 2010 - 05:56 PM

I'm just wondering what opinions there are regarding the above.
If the output is going to be HD (1920x1080), is there really an advantage of having a true 2K scan compared to a true HD scan? I'm not talking about a spirit transfer to HD, but a scan.
In my world of graphics and animation, I've always tried to avoid the re-sampling of pixels at all costs. So if the 2K scan will be scaled down slightly (and re-sampled) to be output to HD, is it worth it? Do you really gain any picture quality is such a scenario? OR perhaps people are just cropping?

Thank in advance,
Tom
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#2 David Mullen ASC

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Posted 14 March 2010 - 06:42 PM

Is there a scanner that does 1920 x 1080 for a Super-35 frame? If so, then I would say, yes, it would probably be better to scan at that size and avoid any scaling. On the other hand, you are downsampling slightly from 2K to 1080P, so I doubt that there would actually be worse results compared to a straight transfer at 1920 x 1080, even if there may not be any real advantage.
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#3 Tom Hepburn

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Posted 14 March 2010 - 07:21 PM

Thanks David. I should have mentioned it was a Super 16 film scan.

Tom
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#4 John Brawley

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Posted 14 March 2010 - 09:40 PM

I'm just wondering what opinions there are regarding the above.
If the output is going to be HD (1920x1080), is there really an advantage of having a true 2K scan compared to a true HD scan? I'm not talking about a spirit transfer to HD, but a scan.
In my world of graphics and animation, I've always tried to avoid the re-sampling of pixels at all costs. So if the 2K scan will be scaled down slightly (and re-sampled) to be output to HD, is it worth it? Do you really gain any picture quality is such a scenario? OR perhaps people are just cropping?

Thank in advance,
Tom



Hi Tom.

I went through this about 2 years ago and did some test for a film, and it's a bit different for me i guess because we wanted a 35mm film finish.

I couldn't really pick much of a difference in resolution between HD and 2k Scans from super 16 using an arri scanner.

Where I did pick differences was in workflow AFTER the scan. You want to make sure you can get the most out of your bit depth and colourspace. So HDCAM instead of HDCAM SR will for example will affect your results. Even on SR then can be big differences between 709 colourspace and LOG as well.

When I was doing it, it was a lot cheaper to scan HD rather than 2k. And it meant I could scan and grade from uncompressed data BEFORE outputting to HDCAM SR which is what we did for the video masters. The film finish was struck from the uncompressed HD data files with it's own film LUT.

jb
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#5 John Sprung

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Posted 14 March 2010 - 11:55 PM

So if the 2K scan will be scaled down slightly (and re-sampled) to be output to HD, is it worth it? Do you really gain any picture quality is such a scenario?


Gary Demos did some research on this back during the ATSC process. His finding was that a slight size change is actually harder to do well than a larger one with a ratio of small integers. That's why Red's quad HD mode is a good idea, it's a 2:1 ratio. HD to 2K is a 15:16 ratio, so there could be a loss rather than at most a very small gain.




-- J.S.
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#6 Tom Hepburn

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Posted 16 March 2010 - 08:56 PM

Thanks again Guys. You given me the feedback I was looking hoping for.
Re-sampling is a last resort for me.
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