Black = 16 is just the digital version of black = 7.5 IRE
no, not quite, they aren't synonomous, they are different both conceptually and in practice. Whether a 7.5IRE setup pedestal is present or not may *seem* very similar to black being placed at 16 instead of at 0, but keep in mind that with digital signals there is really only one video standard, and that places black at 16 universally. When black is at 0, you should consider that a graphics standard, not a video standard. In analog domains, black can be placed legally at either 0IRE, or 7.5IRE, and both are video standards. Further, BOTH of these standards have the full potential to pass and correctly maintain data below black. Conversely, when using a digital graphics mode where black and white are mapped at 0 and 255, respectively, there is no ability to transmit any data outside these bounds, so BTB and peak white data is lost.
The end lesson: do not confuse analog standards, which may place black at 0IRE, or 7.5IRE, and still correctly transmit reference- quality video signals with no degredation, and digital standards, of which only one, with black at 16 and white at 235, is correct for reference-quality video. In an analog domain, with correctly designed equipment, there should be no end-difference whatsoever between using a 0IRE standard, or a 7.5IRE standard(adjusting calibrations between them of course). In the digital domain, there *absolutely* is a difference between using the graphics standard of 0-255 and the video standard of 16-235 (even
when you re-calibrate between them).