What is chroma subsampling?

Chroma subsampling is one of the best strategies for viewing high resolution, high refresh rate content without needing an enormous bandwidth to deliver it. Much like display stream compression, when done effectively it should become almost indistinguishable from its source image.

Image and video de-colorisation work by stripping some color information while maintaining luminance (brightness) information, thus decreasing bandwidth utilization and opening up more room for higher resolution signals and refresh rates, thus making high refresh rate UHD monitors possible – without this technology platforms like Disney+ and Netflix wouldn’t function nearly as well.

Samsung S95C TVs still employ chroma subsampling on their HDMI 2.1 ports for improved video playback quality.

What is chroma subsampling?

Chroma subsampling strips away some color information while keeping brightness information. This reduces bandwidth requirements without substantially altering the final image, though unlike display stream compression which produces visually lossless artifacts on occasion, chroma subsampling does produce occasional artifacts which may only become obvious upon closer examination.

Chroma subsampling’s effectiveness lies within our minds – humans excel at distinguishing between light and dark contrast, yet are less adept at perceiving differences in color nuances; therefore, in chroma subsampled images and videos full brightness data is transmitted while some color data is restricted, creating less variation among images; even trained eyes often find this difficult to recognize without actively searching.

As such, most movies now use chroma subsampling on all major streaming platforms and even UHD Blu-ray, widely considered the highest quality way of watching films. goes.

Here, you can witness the result of various chroma subsampling techniques, and their respective color resolution. The lower images provide additional context.

This image illustrates just how small an impact subsampling techniques with more extreme color resolution loss can make.

How does chroma subsampling work?

A typical video signal consists of two primary components: brightness information and color information. Fully uncompressed signals known as 4:4:4, where each pixel has its own set of chrominance (color) values, are considered the highest quality video available without sub-sampling involved.

4:2:2 is a moderately compressed signal format which includes color information for every other pixel; these pixels copy their neighboring pixels’ colors from time to time, creating two by two blocks where every pixel possesses luminance data while each group of two shares color data – making this ideal for professional video editing, since data rate reduction without diminishing visual quality are key considerations.

Broadcast, streaming and UHD Blu-ray all use more aggressive chroma subsampling formats like 4:2:0 where only every fourth pixel contains color data; two by two blocks will store luminance data but all share color data – although this seems drastic and has an impactful bandwidth cost impact, its near impossible to distinguish the end result between 4:2:2, or 4:4:4 subsamplings.

Chroma subsampling is typically disabled as standard on PC monitors to avoid issues with small text legibility – something more easily noticed on monitors than TVs.

Should you use chroma subsampling?

Chroma subsampling is one of several compression techniques designed to decrease bandwidth requirements when transmitting video, though consumers generally opt for DSC as it remains virtually undetectable and provides additional bandwidth needed for higher refresh rates and resolution.

But this does not render chroma subsampling obsolete – in fact it remains essential in modern streaming services and UHD Blu-ray players that store vast amounts of luminance/chroma information required for 4K resolution video playback.

Chroma subsampling remains useful when working with older displays that do not support digital spatial compression (DSC), as well as being integral part of some still image algorithms such as those for creating JPEGs.

Chroma subsampling remains useful and widely employed across industries and settings; for the average consumer though, DSC might prove more efficient as an approach; being far more modern, its usage might even be enabled automatically so no manual adjustment of subsampling should be needed to use its compression techniques.