What do integrators need to know about color subsampling?
In order to reduce the bandwidth necessary to transmit 4K content, the new HDMI 2.0 specification includes support for 4:2:0 subsampling. This reduces the color information in the signal by 75%, leading to a 50% reduction in bandwidth. Much of the video content currently available is already 4:2:0 subsampled, so there won’t be any additional degradation of the image as a result of the subsampling. However, in other content, such as PC graphics inputs, 4:2:0 subsampling can introduce significant image artifacts. This is especially noticeable in text.
When selecting a product with 4K @ 60Hz support, integrators should be checking what color subsampling factors are supported.
- 4:4:4 subsampling indicates that no reduction of the color information is occurring
- 4:2:2 subsampling indicates a 50% reduction in color information
- 4:2:0 subsampling indicates a 75% reduction in color information
For the highest possible image quality and best compatibility with various devices, support for all three color subsampling factors is recommended.
Special thanks to my colleagues Marques Girardelli for providing this insight.