Do you have a blog? I found this really interesting and would like to read more.
Also, I'm curious - what are the legal reasons for not working with full black or white in broadcast video?
Also, I'm curious - what are the legal reasons for not working with full black or white in broadcast video?
The legal brightness and color usage has to do with the fact that certain levels can cause signal distortion. The details are different, but think of overpowering an audio amp and the distortion you can get. Analog video is a real nightmare of limitations and artifacts. Most facilities I've worked at had signal clippers at some point in their signal chain, but those can cause their own problems. Best to stay away from the cliff's edges. These days HD and digital are much nicer, but there are still a lot of NTSC TVs out there. The situation is a lot like continuing to support older versions of IE.
I'm not sure what the situation is now with digital TV. My last years in the industry were before the mandatory switch, and the places I was working were simulcasting. So we were creating stuff that was NTSC safe. By then most of the software we were using took care of keeping things in spec, but some of the older equipment we were using, mostly character generators and few really cranky old switchers and effects boxes, still required that we be careful about our input levels.
I think you jogged my memory further. I think the way it worked is that the transmitter over-modulation due to illegal levels would/could interfere with adjacent channels and that's why the FCC made the rules.