🚀 go-pugleaf

The point in your illustration where you show the X and say there is
a sine wave there, is known as the color burst. It is a few cycles
of 3.58 Mhz to sync the color. If this is missing from the signal,
color sets think it is a black and white picture and will not trigger
on the color circuits. The color "killer" circuit is triggered by
the presence of this burst.

I have seen black and white pictures, where some video information
in the picture will "fake this" causing the color to trigger on. The
stripes on a referee's shirt at a football game taped in black and
white and then shown on a color set, has been known to trigger the
color on.