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ARRI RAW footage to Log C


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#1 mailesan

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Posted 25 March 2018 - 03:11 AM

What is the meaning of process of ARRIRAW footage to Log C encoding with ALEXA wide gamut color space and how one should be able to do it?


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#2 David Mullen ASC

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Posted 25 March 2018 - 03:52 AM

Depends on your post path for dailies and the final grade. Raw in itself is not viewable until converted to RGB but some color-correction systems can work directly from raw I believe without first transcoding everything. But most colorists prefer to work from a log file. If you record ARRIRAW in camera, then the colorist would probably convert to uncompressed DPX log files for correction, as opposed to recording log in camera, which would require recording a compressed format like ProRes.
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#3 mailesan

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Posted 25 March 2018 - 08:42 AM

Depends on your post path for dailies and the final grade. Raw in itself is not viewable until converted to RGB but some color-correction systems can work directly from raw I believe without first transcoding everything. But most colorists prefer to work from a log file. If you record ARRIRAW in camera, then the colorist would probably convert to uncompressed DPX log files for correction, as opposed to recording log in camera, which would require recording a compressed format like ProRes.

 

Thank a lot David for the reply. Another question, is it okay to grade in Arri Raw format in resolve without converting to Log?. 


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#4 David Mullen ASC

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Posted 25 March 2018 - 12:41 PM

I'm not a colorist nor a post person but correcting directly from raw (basically a converting live) should be fine, if not great, but at some point you are converting -- you probably want to store a log gamma color-corrected master plus the display gamma versions.


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#5 Bruce Greene

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Posted 25 March 2018 - 01:18 PM

All RAW footage must be processed to an RGB working space before color correction. One can do this "live" in the color correction software if one has a powerful enough computer, or one must render a transcoded version to an RGB codec.  It could be .dpx, which is uncompressed RGB data, or something like ProRes 4444, which might be easier to store and work with.

 

Generally, with either workflow, live or transcoded, one converts the RAW data to Arri LogC color space for grading.  This is done by eye, or through a LUT that is usually included with the grading software, such as Davinci Resolve.

 

Another approach is to use ACES, Baselight (if you're using Baselight software), or even Davinci color management.  Here, the transform is done (behind the scenes, so to speak) and you'll be viewing a "standard" correction on your display with access to all the original camera data.

 

With all workflows though, there are settings for converting the RAW data that one needs to set to get started, like using Adobe Camera RAW for still photographs.

 

edit:  In the RAW conversion settings one chooses to convert to Arri LogC, Rec709, or another color space.  The LUT is later used to convert the LogC footage to your working color space.


Edited by Bruce Greene, 25 March 2018 - 01:21 PM.

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