Spatial resolution of color information (chroma) relative to brightness data (luma) — 4:4:4 is full, 4:2:2 or 4:2:0 means subsampling. DCI and broadcast use different standards.
The human eye perceives color information less sharply than brightness information — this is the principle exploited by chromatic resolution. Instead of storing the red, green, and blue channels with identical spatial resolution, the color resolution is deliberately reduced. The notation 4:4:4 means: full resolution for luma and both chroma channels. 4:2:2 halves the horizontal color resolution, 4:2:0 reduces it horizontally and vertically — a standard that is dominant in broadcast, DCI, and many production workflows.
In practice, this directly impacts data volume and processing speed. A 4K recording in 4:4:4 requires about three times more storage space than 4:2:0 — often a knockout criterion for long shooting days on set. Therefore, most productions end up in 4:2:0, either as 8-bit or 10-bit encoding. For color-heavy grading, especially with primary colors or extremely saturated looks, you'll notice a significant difference in the smoothness of color gradients — 4:2:2 is the compromise between quality and workflow practicality. DCI projection often follows a different standard than streaming or broadcast; here, early clarification with post-production and delivery specialists is worthwhile.
On set itself, your choice of camera and recording format is crucial. Some digital cameras offer you the option to choose between 4:2:0 and 4:2:2 — there you can opt for higher resolution if storage and data rate are not an issue. During color correction in the edit, this subsampling has an effect when you apply aggressive curves to individual color ranges or work with masks; less chroma information means less freedom of movement and a higher risk of artifacts. The workflow advice from years of practice: clarify the chromatic resolution not only in the edit, but together with your DIT and Colorist in the pre-production meeting.