[Sidefx-houdini-list] Film at 16 bit

Ivan DeWolf ivan at martian-labs.com
Fri Mar 7 16:55:53 EST 2008



the internal format you work in is often different than the final format
delivered for scannig/layoff. Usually, footage is scanned in to a 10-bit log
file (often a cineon format file) and delivered to be put to film in that
format; 10 bit log makes sense for recording to/from film, but it doesn't make
sense to work with when compositing. To convert a 10-bit log file to a linear
file without losing data, you need 16 bits of data; hence the "standard" of 16
bit linear output. converts neatly to 10-bit logarithmic color space.

Often, it is useful to work internally in floating point space, particularly
when dealing with odd lighting effects; floating point doesn't clip bright
values or posterize dim regions.

I would suggest if you have the diskspace and can tolerate the network traffic,
work in 32-bit floating point colorspace. Render 32-bit float, composite in
32-bit float, and at the very end convert it all into your 10-bit log file. 
That way, if you need to push your colors around, you have ample headroom.



Quoting Larry Giunta <larry at gcreativestudios.com>:

> I was hoping to hit you film guys and gals up for just a bit more  
> advice about rendering for 2k film.
> 
> Just wondering, of the available quantization option on the mantra  
> output drive,
> if there is any one that is considered a "standard"?? .....  or if it  
> varies widely depending on the shot, production. etc.
> 
> I re-read Jeff's old school blog on the subject which makes it pretty  
> clear that it needs
> to be at least 16 bit. I'm just wondering what might be the best  
> choice to consider.
> -16 bit integer
> -16 bit float
> - 32 bit float
> 
> Background on this particular shot we're producing is
> 1. It will be rendered in mantra, composited and output from COPs
> 2. There is no live action, not many textures.
> 3. It's very heavy on volumetric light ( bursts and light beams, that  
> sort of thing) lot's of blurring etc at the COP level.
> 
> While I'm at it, I guess I'll ask about preferred image format. I was  
> assuming 16 bit tiff, but not sure if that's best
> 
> Anyway, sorry if these are somewhat basic questions but would very  
> much appreciate any thought from those who have
> more experience with film.
> 
> Thanks as always,
> 
> Larry
> 
> -- 
> Larry Giunta
> Creative Director
> G Creative Studios
> (781)393-0200
> larry at gcreativestudios.com
> www.gcreativestudios.com
> 
> 
> >
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-Ivan

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"Perfection is achieved when nothing else can be removed"
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