On Fri, 8 Feb 2013 06:49:10 -0800, "William Sommerwerck"
wrote:

The B&W contains spectral peaks at multiplies of line and field rate.
For (stationary) images, there is no energy between the spectral lines.

This is not correct, unless every line is like every other line. The normal
variation in vertical details causes the peaks to "smear" somewhat.

I have quite often used the following example what the B&W signal
looks like:

There are quite often repeating hills every 15625 Hz with a tree
standing at every 25 Hz starting from the top of the hill

With severe wind (image movement) the tree branches will be mixed
with each other, making it impossible to separate luminance and
chrominance properly.