Chroma Subsampling
Definition
Chroma Subsampling is a type of video compression that reduces the amount of color (chroma) information in a video signal relative to the luminance (brightness) information, based on the fact that the human visual system is more sensitive to brightness than to color. Chroma subsampling is expressed as a ratio (e.g., 4:4:4, 4:2:2, 4:2:0), where the numbers represent the ratio of luminance to chroma sampling. 4:4:4 is full color, with no chroma subsampling; 4:2:2 samples the color at half the horizontal resolution; and 4:2:0 samples the color at half the horizontal and vertical resolution. Higher chroma subsampling values are preferred for professional production and VFX work.
Contextual Usage
The VFX supervisor specifies the camera settings for the green screen shoot: "We need to shoot in 4:4:4 or at minimum 4:2:2 for the green screen sequences. If we shoot in 4:2:0, we won't have enough color information to pull a clean key in post. The reduced chroma resolution will make the edges of the key look ragged and noisy."
About this section
Color grading and finishing is the final visual polish of the image — the stage at which the raw footage is transformed into the rich, cinematic image that the audience will ultimately see. A skilled ...
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