#Greg's new toy
It's not that simple. Yes, there are 8 bits for each luminance, R-Y, and B-Y.
The difference is that each pair of pixels share the chroma so it takes two
pixels to get both R-Y and B-Y. Luminance (Y) is unique for each pixel. The
physical layout is 16 bits pixels but you need 32 bits before you can make
sense out of a single pixel. On top of that, the dynamic range is limited. Not
all bits of a signal are used. There are around 220 possible values for
luminance and 224 for chrominance. The 16 million figure is somewhat pointless
as you would need a monitor with a 4,096×4096 resolution in order to show all
of them. This also assumes that no single pixel is repeated.