scaling > S C A L I N G > scaling
The Bain of our Existence. The inescapable issue of any set-to-post workflow and every new project begins with a lengthy dialog on the topic.
Not to keep beating a dead horse but this is something that just will not die. As long as there's Rec709 video, there will always be scaling between Video Levels and RGB Data levels. There's just no way around it. The good news is that scaling is a numerical constant so as long as you know where in the image processing chain it's happening, predictable and repeatable results can be created. In the case of Alexa on-set workflows, because scaling can happen on the camera's video output, in painting software, and in the linearization LUT, the exact same results can be created with various combinations of Legal and Extended Levels. At the end of the day, it's all the same.