What does Chroma subsampling mean?
Chroma subsampling reduces the spatial sampling of colour components relative to brightness-related information. Formats commonly described as 4:2:0,4:2:2 and 4:4:4 represent different sampling arrangements rather than universal picture-quality scores.
Why it matters
It is a deliberate compression trade-off used widely in video. Natural footage can tolerate reduced colour resolution better than tiny coloured desktop text. Source sampling and HDMI output sampling are separate stages; selecting a richer output cannot reconstruct information already removed during encoding. Resolution, refresh rate and bit depth also affect which output combinations a connection supports.
A practical example
For film viewing, a compatible subsampled signal can look excellent. For a television used as a computer monitor, fine coloured letters may reveal a need for a supported full-chroma desktop mode. Test the actual task instead of assuming one setting is required for every source.
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Related terminology: Chroma, Closed captions.
For practical setup and troubleshooting, browse the journal or support guides.