Loading with an accurate colour space

So I have a Blackmagic Cinema 2.5K Camera - it comes with Resolve, which is supposedly the top grading tool, but I spent a day trying to learn it and was constantly thinking that I could achieve the same thing much faster in Blender. Its probably not a bad reflection on Resolve as simply the case that I am much more familiar with Blender and its colour nodes, plus being a mathematician means that I find the full node editing approach much more to my taste than Resolves ‘everything is a special case’ interface. Resolve actually reminds me of my washing machine for some reason - probably all the circular dials and the fog of abject terror that descends;-) Additionally, rebooting into Windows just to grade is silly.

Anyway, the weakness with Blender is the colour space - the Blackmagic saves in a log colour format (Using ProRes - preparing to make a documentary, and RAW would blow my hard drive budget.), and Blender does not have such an option when you load the files (which load fine and have the full 10 bits available). Now, if your not afraid of maths its reasonably easy to set the loading file format to linear and then setup nodes to convert the input into actually linear - you can find the Cineon Log C paper, which is I think roughly what Blackmagic is using, and express those equations as nodes in Blender. Its not spot on though - Rec 709 is not the same in Blender as it is in Resolve, but its not crazy different either. It does however require you to set a white level and black level, though setting the black level to full black and tweaking that later with a curve makes the most sense. Now the colour space is a little fuzzy at this point - you have linear values, but with an unknown scale and unknown primaries, but you have linear so you can attack it with Blenders nodes and get good results (Really good in fact - the image from the Blackmagic is just gorgeous, and whilst there are a bunch of nodes I wish Blender had the current set is still really powerful.).

After all that, the question is, does anyone have any clue how to do this properly in Blender? I understand its possible to edit a file and add further colour spaces (you would always have to follow loading a file with LogC colour space by adjusting the black/white points, which is not much more convenient, but is at least an expected work flow.), but anyone know how I could get a ‘true’ colour space for the Blackmagic? I have checked and Blackmagic don’t publish anything useful in this regard, or at least other people are complaining that only Resolve has the correct LUT and others have created their own (e.g. http://www.captainhook.co.nz/blackmagic-cinema-camera-lut/). I can point the camera at a MacBeth ColorChecker under controlled lighting for instance, but here my knowledge of colour spaces starts to get fuzzy, and, more importantly, converting the output information into some kind of continuous lookup table that Blender can dance with is totally outside my experience - I am not even sure if its possible?

So, anyone have any knowledge of how I could go about doing this? I am basically trying to judge feasibility here - I have an OK solution, but would prefer to start grading from accurate colours. (Yeah, I realize I am well and truly into the arcane…)

I spent a day trying to learn it

I suggest you spend a few more days…
In my opinion, re-inventig the wheel is going to take you a lot longer and might be a very frustrating experience. (But I’m one of those who find washing machines quite hypnotic)

Blender doesn’t get better if people don’t find these crazy use cases and get them working though - that is a big part of how Blender got to be the cute little monster that it is. Besides, I am already in a position where I would choose Blender over Resolve - I just want to make it better, and in the process maybe get Blender a little closer to something a pro may choose:-) After all, if we ever get to the point where professional production houses are making regular use of Blender we will suddenly find their dev teams contributing to Blender on a regular basis - at that point it becomes the blob and eats everything…

You should pm the user Yellow here or leave a message on the blog in my sig below. He is the blender color conversion expert. Also contact troy sobotka another blender color genius.

Thanks - I’ll do that:-)