Field Blending
From SDA Knowledge Base
Introduction
Field blending, also known as "ghosting" is a deinterlacing method that is unacceptable at SDA. It's too easy to get stuck with a cheap capture card and cheap software that will produce a video with this effect. I think there may also be some fault with the user. People new to video capturing/editing will think they've done something wrong when they see "all those weird lines" in an interlaced frame and choose a different and incorrect interlacing setting, most likely progressive field blending.
The field blending process
1. A single interlaced frame. It has two distinct fields, which I will call field A and field B, happening a split second apart. |
2. The fields have been split. Field A has the even-numbered lines, while field B has the odd-numbered lines.  |
3. The actual vertical height of field A and B. Nothing necessarily bad has happened yet...  |
4. Problem number one! The fields are resized to the original height. Vertical detail is lost.  |
5. The final stage. Field A and B are blended together at different opacities. The result is a "ghosting" effect. |
More examples
