RGB (red, green, blue) explained

The short explanation

Video can be sent as RGB or as YCbCr, which separates brightness from color so the color can be subsampled. RGB carries full information for every pixel and cannot be subsampled, so it is comparable to 4:4:4 in bandwidth.

Where you run into it

For a PC, RGB or 4:4:4 is what keeps text crisp; a subsampled signal makes colored text look fringed. For film and television it gains nothing, because the content was mastered subsampled anyway.

The classic trap is the black level. RGB comes in full range (0–255) and limited range (16–235), and a mismatch between source and display produces washed-out blacks or crushed shadow detail — a picture that looks wrong in a way that is hard to name.

How the DR HDMI 8K handles it

The DR HDMI 8K shows the color space listed in the RX and TX EDID on its OLED, and its EDID library includes explicit RGB tables such as 4K30 RGB at 300MHz with BT.2020, with and without HDR. In the Dolby Vision section the 444/RGB 10-bit or 12-bit support has a setting of its own, so RGB capability can be advertised deliberately.