[mythtv-users] a little OT: deinterlacing question

[jason maxwell]

I am just curious. Why is deinterlacing so difficult? From what I've
read on the topic, an interlaced image is created by breaking a single
frame into 2 fields of alternating lines. It seems to me that
reassembling the full frames should be as simple as combining the odd
and even fields back together. Yet, from what I have read, this will
always result in some artifacts, most commonly, tearing (mouse teeth).
Why is this?

Also, If interlacing was designed to overcome bandwidth limitations of
the past that no longer plague us, and properly deinterlacing on
anything but the soon to be extinct CRT monitors is so problematic,
WTH is 1080i an acceptable standard today?

confused,
-Jason