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Filmmaking Dictionary: Number 4 / 4:2:2 Chroma Subsampling
Definition
4:2:2 chroma subsampling preserves full luma sampling while each colour-difference channel is sampled at half the horizontal rate and the full vertical rate. It retains more vertical chroma detail than the common 4:2:0 arrangement.
The notation describes relative colour sampling. It does not specify resolution, bit depth, codec, bitrate or whether the recording is compressed.
A Simple Comparison
Across a four-sample-wide row, the luma channel has four samples while each chroma channel has two. The same relationship applies on the next row. By comparison, common progressive 4:2:0 also reduces the vertical chroma sampling rate.
This makes 4:2:2 useful in many production and post workflows where colour-edge detail needs to survive editing, grading and compositing. It still discards some spatial chroma information compared with 4:4:4.
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Why the Full Recording Specification Matters
An 8-bit 4:2:2 signal and a 10-bit 4:2:2 signal share a sampling pattern but have different numbers of representable code values. Two 10-bit 4:2:2 codecs can also use very different compression methods and bitrates.
For example, a camera may offer one sampling format internally and another through its video output. Selecting a high-quality recorder preset cannot recover information the camera output does not supply. Confirm the entire chain, including resolution and frame rate.
Practical Uses
- Colour correction: Preserve useful chroma information through normal adjustments.
- Compositing: Give keying and edge work more colour sampling than a comparable 4:2:0 source.
- Broadcast workflows: Meet a specified acquisition or delivery format where required.
- Intermediate files: Reduce additional losses while passing material between applications.
Those advantages do not compensate for a poorly lit green screen, clipped highlights, missed focus or excessive noise. Test the actual task rather than assuming the numbers guarantee a clean result.
Common Mistakes
- Using ‘4:2:2’ as a synonym for 10-bit.
- Assuming every camera mode supports the same output sampling.
- Expecting a transcode from 4:2:0 to restore original colour detail.
- Ignoring repeated lossy exports because the sampling notation remains unchanged.
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Frequently Asked Questions
Does 4:2:2 include an alpha channel?
No. Transparency support is a separate property of the format.
Is 4:2:2 always better than 4:2:0?
It preserves more chroma sampling in the vertical direction, but overall image quality depends on the source and the rest of the encoding.
Related Terms
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