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Topics - baldavenger

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General Chat / Linear raw to percentage to IRE in resolve
« on: January 08, 2016, 09:18:40 PM »
Apologies for what is probably a very noobish enquiry, but what are the values associated with 18% and 90% scene reflectance? For instance, when viewing a dng in Resolve in linear space and 18% scene reflectance is 20 IRE on the waveform scope (and 90% is 100 IRE), which original 14 bit values are they derived from? If white level is 15000, how many stops above 90% reflectance is that?

Many thanks in advance to anyone who can help clarify this for me.

Raw Video Postprocessing / DaVinci Resolve and ML Raw
« on: September 01, 2015, 11:41:51 PM »
The latest release of DaVinci Resolve (free version) makes working with ML Raw video a doddle, and thanks to developments such as MLVFS the overall post-production process has come a long way since the early days.  Anyway, this thread is for anyone who wants to post advice and tips with regards to using ML Raw and Resolve 12.

The introduction of Resolve Color Management is the big game changer.  My preferred method is working in Alexa LogC, and this is now I go about it:

In the Master Project Settings, choose DaVinci YRGB Color Managed (as opposed to the default DaVinci YRGB)

In the Color Management section of Project Settings there is Input Colorspace, Timeline Colorspace, and Output Colorspace.  The way RCM works is that it converts all footage to Scene Linear at the initial stage and from then on it converts to whatever colorspace is selected for the timeline, and from there onto the output transform.  For non raw footage, it's necessary to correctly input the footage colorspace otherwise the process won't work properly.  With raw footage that's not necessary, as RCM can directly debayer into your chosen Timeline colorspace.  The same goes for Output Colorspace, but I select Bypass in the options as I prefer to see what's going on under the hood.

Selecting Alexa LogC for Timeline Colorspace, and Rec.709 Gamma 2.4 for Output Colorspace (it doesn't make any difference what is entered in the Input Colorspace field with raw footage), the image you see on your monitor will be the same as the one you see when you're in normal DaVinci YRGB and you picked Rec.709 for Color Space and Gamma in the Camera Raw panel.  By selecting Bypass as the Output Colorspace option, you will see your image in LogC Gamma and Alexa Wide Gamut.  The Arri LogC LUTs that come with Resolve don't expand the signal out to Gamma 2.4, which is annoying, but there is a solution to this.  A free website that produces and coverts LUTs.  It's awesome.

Here's a screenshot with the settings I used to generate a LogC Alexa Wide Gamut to Rec.709 Gamma 2.4 LUT.

The website can be used to generate Gamma or Gamut only LUTs, so you can isolate both parts of the process.  You can also import a LUT and modify it for your needs.  Very handy if say you like the colour transform of a LUT but the contrast is too much and you'd rather replace the Gamma function with something more appropriate, or even remove that part altogether and do the tone curve yourself.

That should do for now.  More updates will follow  :)

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