working with 10bpc cineon and CG

[beaker]

the cineon files i have dealt with in the past have always been washed out and to view them in an near as damn it end result i would run a cineon converter in after effects as a top of the comp adjustment layer

but what i want to know is the best workflow/practice for using these washed out layers when combining with cgOk, so when you scan film it is in a colorspace called logarithmic or Log. When you push it through After Effects you are translating it to gamma corrected linear colorspace (often called just Lin or linear). Esentially making translating it from filmscanner's language to how your eye sees it through your monitor(the monitor has it's own colorspace).

A) better to run the washed out cineon files through after fx converting them to end result images and THEN create CG to match that, then run the reverse cineon converter on the cg before doing the comp? (my problem with this is that there is a descrepency between footage which has been cineon converted log to lin, then lin back to log. obviously it wont be a non destructive process, but the difference is noticable enough to almost throw all CG matching in the 3d app outClose. You should translate it from Log to Linear in AE. Composite the CG on top of it. Then at the very last step you should translate to Log space and output Cineons for the Film Recorder.

The Art and Science of Digital Compositing:
http://www.amazon.com/Science-Compositing-Kaufmann-Computer-Graphics/dp/0121339602/ref=sr_1_1?ie=UTF8&s=books&qid=1202446916&sr=8-1

Digital Compositing for Film and Video:
http://www.amazon.com/Digital-Compositing-Film-Video-Second/dp/024080760X/ref=sr_1_5?ie=UTF8&s=books&qid=1202446916&sr=8-5

Compositing Visual Effects: Essentials for the Aspiring Artist:
http://www.amazon.com/Compositing-Visual-Effects-Essentials-Aspiring/dp/0240809637/ref=pd_bbs_sr_3?ie=UTF8&s=books&qid=1202447047&sr=8-3

Also fxphd teaches a compositing for After Effects class:
www.fxphd.com

[victor throe]

hi

thanks for posting such a comprehensive reply

a couple of further questions:

how much, if any, variation on the resulting image is there once it has gone through the log to lin for compositing then lin back to log for exporting?

i was afraid it was too high and therefore worked under an adjustment layer, but this had a huge impact on my ability to light in the 3d app.

i will check out those links and very much appreciate the help.

as a final point: when pulling a matte from 10bit files, would it also be advisable to convert to lin for keying or is the colour range more accurate on the default log? i personally found the level of noise produced less artefacts in keying when left in log

[victor throe]

my library had those books in stock...i know what im doing all weekend

and on a personal note.....you would not believe how long it took me to find a book called 'bluescreen compositing' on the shelf because the cover is green......i ran my finger across it 4 times....my brain completely blocked it out

it wasnt until i looked it up on the computer and saw it was green did i find it

probably a whole paper written about that kind of thing

[Aruna]

how much, if any, variation on the resulting image is there once it has gone through the log to lin for compositing then lin back to log for exporting?

There should be no color variation when you output back to log cineons, unless you're applying a color grade or post color correction as requested by the gods above.


as a final point: when pulling a matte from 10bit files, would it also be advisable to convert to lin for keying or is the colour range more accurate on the default log? i personally found the level of noise produced less artefacts in keying when left in log

You'll find different opinions on this, but I've always keyed in float linear.

[victor throe]

There should be no color variation

but if you convert log to lin and then stick a lin to log ontop of that the result is not the same as the original log......or maybe im doing it wrong

i use the cineon filter in afx to do both conversions....is there another way?

[beaker]

What bit depth are you working in?

[Aruna]

Does After Effects work in float space? There have been tales of using a log/lin node in some packages, and the resulting linear file will be clamped, and when you put a lin/log back onto it, it totally changes the bright values. This may be what's happening here.

What bit depth is After Effects set to?

but if you convert log to lin and then stick a lin to log ontop of that the result is not the same as the original log......or maybe im doing it wrong

i use the cineon filter in afx to do both conversions....is there another way?

[beaker]

After Effects 7 added 32 bit float support.

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