Display Bit Depth Demystified
Another seldom thought of aspect of newer displays is bit depth. Most HDTVs were/are 8-bit which means they can display 256 gradations or shades of a particular color. For instance, from white to black there are 256 shades - 254 shades of gray with white and black. Breaking it down further, each pixel of a display consists of a red, green, and blue portion. There are 256 gradations of each of these three colors. And since each of these is responsible for producing whatever color the content is calling for in that pixel, an 8-bit panel/display each pixel is capable of reproducing 256X256X256 colors or 16,777,216 different colors.
Newer UHD/HDR displays are now capable of 10-bit color which expands the number of shades/gradations from 256 to 1024. With 10-bit color you get 1024X1024X1024 colors or 1,073,741,824 different color possibilities. That is quite the difference! So, what does this mean? It means that the gradation/blending of colors in scenes is smoother on a 10-bit panel. A good graphical representation of this is shown below:
What does the future hold? We are already at phase one of the UHD roll-out which includes HDR, 10-bit depth, Rec.709 color space, etc. The next phase will be the addition of 12-bit displays, BT.2020 color space, 4:4:4 subsampling, etc. 12-bit displays will be capable of 4096 shades of red, green, and blue for just under 69 billion colors. The final phase will add 14-bit displays capable of 16,384 shades of red, green, and blue for just under 4.4 trillion colors.
What does this mean to you? What it means is that you will have smoother more natural looking image on your display. The way that bit depth issues are normally described is called banding or color banding. The transition from darker to lighter colors on better performing displays (10-bit and up) is much smoother than those of an 8-bit display. It should also be noted that 10-bit color depth is only available on HDR content. Everything else - cable, satellite, Blu-ray, game consoles, PCs, etc. - is 8-bit.
If you have Netflix you can view a test pattern here. Look at the gray ramp up on the top of the pattern. What you are looking for is banding in the grayscale ramp.
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