In SDR content, colors are encoded with 8-bits ranges. So, 24bits for the three color channels. With HDR, we usually use 10 bits instead (this is where the "10"

In SDR content, colors are encoded with 8-bits ranges. So, 24bits for the three color channels. With HDR, we usually use 10 bits instead (this is where the "10" comes from in "HDR10"). See https://en.wikipedia.org/wiki/Color_depth#Deep_color_(30-bit) https://en.wikipedia.org/wiki/Color_depth#Deep_color_(30-bit....