I understand that RGB 888 means 8 bit per color and pixel, which gives us the very well known "16.7 million colors".
I also understand 4:4:4 for luminance/chrominance coding in YCrCb.
What I don't get at the moment is RGB 4:4:4 in the HDMI standard:
See chapter 6.5.1 of http://www.microprocessor.org/HDMISpecification13a.pdf:
I can't help but understanding this as RGB 888: Each Pixel is transmitted on three channels, where each channel (or "component") carries 8 bit of color information.
So, why is it called RGB 4:4:4?
Or is my understanding completely wrong?
Best Answer
This isn't related to bits but to an area of nx2 pixels on the screen. Please read
https://en.wikipedia.org/wiki/Chroma_subsampling
RGB 4:4:4 means RGB, no chroma subsampling. It's the only mode which makes sense for RGB because RGB hasn't chroma separated from luma.