Picture Judder

[Alexia]

Here's a question : why, especially I've noticed on soccer coverage, when the camera zooms in for a close shot and there's a slight judder (like the camera is being held by someone with shivers) do some parts of the picture move more than others? For example, on tonight's Eng v Pol match, a zoom in on the goal line during a corner showed the white of the post and goalline appear to shudder more than the grass around it.

[Nick Harvey]

It's all to do with digital compression and the white line being smaller that the green pitch, but I'll leave it to someone more technically up-to-date to go deeper into it all for you.