I work as a compositor for around 5 years. All my work is for TV and in these years no one I mean no one even mentioned that the thing we call linear color space is not actually linear – its sRGB or rec709. I started reading a bit about it, found some info here, some on prolost and other sites. I know now that so called linear color space is acutall "video" color space thats not linear – the gamma is above 1. Now I know what is the reason of chaning saturation while you change gamma of an image – in some extreme situations when you got float color detail when you move your gamma high enough your color will go to negative ( for example from yellow to blue ). So that proves to me that its not a real linear color space. and I can understand that.
I know that you have to invert 2.2 gamma when rendering ( using 0.45 gamma ) to get real linear color space. you can work in linear fashion and at the end you move it back to rec709.
So my real question is, what are the adventages and disadvantages of pure linear compositing. I did my comps in video color space all the time, and noone even mentioned that there are other ways of doing that.
One good reason for me at least, to stay in video color space is the fact that what I see is what I get at the end. I dont have to keep in the corner of my mind "how things will look after convertion" for broadcast.
2nd thing puzzles me a bit more.
Since we do film work quire rarely, like 2 times a year top. There were always 2 ways of work.
– you get DPX log files, convert it to "linear" -> video color space. Work on them, then do the opposite transformation from lin2log and print it on film.
– or just ask the scanning facility to deliver 16bit DPX in linear fasion.
and pray that the colors you saw on your screen will be the same in the big screen
I never could understand the real bulletproof workflow when it comes to color.
from what I understand you can work in Log all the way – but then you put display LUT that converts DPX log color space to your monitor ( sRGB space ). How do you make that LUT file.
Maybe it is safer to convert those files to linear and work from there.
What is your experience in those 2 subjects. Help out guys. its a bit confusing since noone can realy explain it to me. Everyone just … ha yea you should do hmmm…. of course linear … read it on the net. and thats it. 99% of the ppl i know in the industry dont have a clue regarding that subject.
thanks in advance
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