4:2:0 - whats that all about?

[Jerome Marot]

Originally Posted by Tim Ribich

Given the different compression methods being discussed here, is it likely that the average (whatever that is) viewer could really tell the difference in a real world application?

Yes, and it is quite easy to find out. Chroma subsampling is quite noticeable when you have objects with bright colors in front of a background of a similar darkness. For example a yellow shirt in front of a light background or a red car in front of a grey wall. It is also a problem when filming on stage with saturated colors, red or blue noticeably.

OTOH, all end distribution consumer formats use chroma subsampling, so the solution is not to get a better camera, but to avoid filming problematic material.

[Kevin Shaw]

Keep in mind that the amount of chroma information is relative to the overall resolution of the image. Most HDV (1080i) cameras record 720x540 chroma samples per frame, while SD video at 4:2:2 only has 360x480 chroma samples per frame. The issue for broadcasters isn't just the amount of chroma detail but rather the overall image quality including everything from lens aberrations to depth of field and ability of footage to survive the rigors of broadcast transmission. Small cameras are generally disdained by broadcasters regardless of the recording format: the BBC puts the same limitations on the HVX200 that it puts on HDV cameras.

On the other hand, get a useful shot in any format and broadcsters may use it: more and more cable news is being sent via the reporters' cell phones. Content rules...