Color depth, or bit depth, quantifies how many unique shades of color a display can produce for each individual pixel. Screens create colors by mixing Red, Green, and Blue (RGB) light. The bit depth dictates how many levels of intensity each of those three color channels can output.
In an 8-bit display, each color channel (Red, Green, Blue) has 2^8, or 256, possible levels of intensity, ranging from 0 (off) to 255 (max brightness). To find the total number of possible colors, you multiply the channels: 256 × 256 × 256 = 16,777,216 colors. This is the standard 'True Color' used by almost all standard web content and SDR monitors.
The leap to 10-bit and HDR
A 10-bit display increases the data to 2^10, or 1,024 levels of intensity per RGB channel. The math scales exponentially: 1024 × 1024 × 1024 equals 1,073,741,824 colors. Moving from 8-bit to 10-bit doesn't just add a few colors; it increases the color palette by a factor of 64.
This massive expansion is a fundamental requirement for High Dynamic Range (HDR) content. HDR expands the brightness range of a display. If you stretch 8-bit color across a massive HDR brightness range, the gaps between the 256 color steps become visually obvious, a phenomenon known as color banding.
Identifying color banding
Color banding is most easily spotted in gradients, such as a smooth blue sky transitioning to a sunset. On an 8-bit display, you will often see distinct, harsh lines separating the shades of blue because the display literally lacks the mathematical in-between colors to render a smooth transition.
A 10-bit panel has enough intermediate shades (1,024 per channel) to make gradients appear perfectly smooth to the human eye. It is important to note that many cheaper monitors advertise '10-bit' but are actually 8-bit panels using FRC (Frame Rate Control)—rapidly flashing between two colors to trick your eye into seeing a third, intermediate shade.