I'd love if you were able provide some reading on "superblack", or even just explain it yourself.

I'm not a TV engineer, I was a journalist, so here's what I remember:

Superblack was a special kind of black. When you watched analog TV and the video faded to black, the screen was black. But that was a transmission black. It wasn't as black as was electrically possible. There was always still some signal there generating not-quite-black.

The not-quite-black was largely an artifact of video tape, and all the dozens of machines a video signal had to go through from playback to broadcast. If you were watching black recorded on tape, it was never quite black. An ordinary person would never notice that it wasn't perfectly black, but you could see it if you were in a TV station with oscilloscopes monitoring the signal at various points in the video chain. IIRC, it was like -1db, or something like that.

You could see it at home, if you tried. If you knew what to look for. The easiest way to do it was to turn the brightness up on your TV and look for the dark dark dark grey at the beginning and the end of commercial breaks. That wasn't superblack, that was regular black. But superblack would be next.

In a videotape room or an editing suite, you could see superblack quite easily. Watching a tape with black on it on an analog monitor showed regular black. When you ejected the tape, the monitor would go a shade darker: superblack. The blackest the monitor could electrically be without actually being off.

Superblack could be used for all kinds of things. I only remember three off the top of my head.

First, primitive chroma-key effects in the days before digital video. It wasn't great, and you'd need extra equipment down the line to boost the signal because it would get dark, and then boosting the signal made it look bad, so it was rarely used.

Second, the equivalent of today's alpha channel compositing. This was more common, but still resulted in some signal degradation. But it was how you could put chyron or an OTS over video or a live signal.

Third, was the TV station equivalent of a "silence sense." When I worked in radio, each station had a gadget called a "silence sense" that would be hooked up to an ordinary radio tuned to the station. If there was silence for longer than x number of seconds, it tripped a relay that flipped on red blinking light bulbs in the DJ booth, in the newsroom, in the PD's office, in the MD's office, and if you were unlucky, the GM's office. In non-studio locations it was often accompanied by a beeping noise. The idea was to let everybody in the building know that something had gone horribly wrong and there was nothing on the air. Some stations I worked at it was set for 10 seconds. Some as few as 3. Really, it depended on the type of music the station played.

A similar gadget could be made (most of these things were home-made by the station engineer) to look for superblack in a TV signal. Too much superblack, and alarms go off everywhere.

Fourth, Panasonic is the only company I know of that used superblack in the consumer arena. It made a VCR that, after a show was recorded, would automatically rewind and re-watch the show for you. When it sensed superblack, it would mark the location on the tape. Then when a person went to watch what was recorded later, the VCR could sense the marks it made previously and use them to fast forward through the commercials in the program. This worked because there would always be superblack inadvertently broadcast at the start and at the end of each commercial set where there was a break in the video chain from the switch between the show playback machine and the commercial break's playback machines. I had one of these machines. It worked really well, except that it made all kinds of chugging and whirring noises in the night while it marked the tape.

Again, I'm not an engineer, so I'm just working from memory. But I'm typing what I know here because so much information about these sorts of things has disappeared, and the people who know more about these things are mostly dead.