ALL video stored on modern discs, be it DVD or Blu-ray, are stored as YCbCr with a range of 16-235. But, the content is mastered such that 0-255 is present in the tape domain (the SDI stream - D5 archive tape, etc.) It is then captured into a computer and then the computer will decide what to do with it - preferably retaining the extended info (all data from 0-255). This entire range is then compressed into the 16-235 range accepted by DVDs, Blu-ray Discs, etc. When you play that back on a system set to 16-235, you get all the information as it was intended with no gaps. If you mismatch and play back with RGB (0-255) settings, you'll clip off the black and white levels and black will look "dark gray". Additionally, you won't be able to view the Blacker-than-Black images found on most video test discs.
This makes it seem as if what was originally the darkest possible black (RGB 0), is now represented as 16 in the YCbCr format.
So suppose when a disc is mastered, there's a scene where everything fades to black. The individual(s) mastering the disc decides that this black should have a value of 0 (see bolded part of above quote). So, when the information is compressed into the 16-235 range, this scene will be associated with a value of 16, and this will instruct the blu-ray to instruct the TV to output the darkest black possible.
So how on earth can there be darker than black patterns that you're NOT supposed to see after proper calibration?
In order to see Blacker-than-Black test patterns, you'll need one of the discs below which will give you the ability to calibrate your display or projector to the correct levels. Remember, the proper level is such that the below black information, while present in the system, is NOT visible. TYhis means that you will want to make sure that the Below Black information comes through by cranking up your Brightness (black Level) until you see the below black pattern, and then decreasing Brightness until it is completely hidden, but leaves the next brightest pattern or line barely visible.
The second quote (taken from same article) implies that when the mastering was done, the original 0-255 range was not COMPRESSED to 16-235, but rather CLIPPED to 16-235.
This clipping idea would also be in line with something I remember Michael Chen
said about how it's important to calibrate properly so that you don't see stuff like boom mic's and things that are mastered as blacker than black.
So I'm pretty confused here. Any insights would help!
edit: after studying the issue some more, it seems as if Reference black is not 16, but rather somewhere above 16 (that somewhere being 7.5 IRE). See top right of this image
, taken from same article.
So it appears that while during the mastering process, compression is what occurs, not clipping.
But apparently, we're supposed to manually crush the blacks so that everything up to 7.5 IRE is rendered as complete black. And this is done just so that boom mics become invisible? That sounds like a really crappy way of doing things, as it reduces the levels of luminance even more! At least I think I understand what's going on (even though it seems silly to set black levels above 16).