I'm confused, from what understand "scene referred" means working in a color managed workflow, manipulating the image before the transformation giving you the flexibility to convert and output to different color spaces without having to start grading from scratch to conform to a different colors space. In the other hand "display referred" is where you are basically doing your grading based on what you see in your monitor and outputting to that instead of using color management transforming your final render to the desired color space. So what confuses me is why do I see "Rec.709 (Scene)" in the non color managed menu. Shouldn't it say "Rec.709 (Display)" because grading in the non color managed setting is displayed referred?
Please educate me because this seems to be complete opposite of what I learned.
The expectation of the "standard" Rec.709 video handling is that the file will be viewed with *both* the camera transfer function *and* the display transfer function. They are both called for in the full specifications.
You are *expected* to grade it with the display transform applied.
Rec. ITU-R BT.709, referred to commonly simply as Rec.709, defines a set of primaries for HD video. Although it is common to refer to a “Rec.709 monitor”, the Rec.709 standard in fact defines only a camera OETF (which is in reality rarely applied exactly in any cameras) and does not define the EOTF of the viewing display. There was therefore some debate as to the correct EOTF for displaying Rec.709 image data until Rec. ITU-R BT.1886, commonly called simply BT.1886, was introduced in 2011.
While the definition only of an OETF makes Rec.709 notionally a scene-referred encoding, in broadcast use camera settings are often modified from the pure OETF for creative reasons, and to cover a wider scene dynamic range. Indeed many cameras’ default “Rec.709” mode does not conform exactly to the standard. This means that the mathematical transform to revert to scene light is unknown, so it does not fit the strict definition of being scene-referred. It therefore becomes what Charles Poynton (in the list of definitions in Appendix A of his PhD thesis) calls “mastering-display-referred”.