Apple Shake 4 - Manual (Page 195)

Chapter 6 Importing Video and Anamorphic Film 195
Another issue arises when you apply image rotation and scaling to an interlaced clip. In
the following images, a rotation effect has been applied to two images, one with field
rendering and one without field rendering. The right image will appear correct when
played back on a broadcast monitor, because the interlaced lines are properly arrayed.
The lack of clearly defined fields in the left image will cause undesirable artifacts during
video playback.
Filters and Fields
Field rendering doesn’t just affect spatial transformations. The examples below depict
close-ups of frame 1 (from above), without and with a Blur node applied. Look at the
second image. When the blur effect is applied uniformly to both fields, the result is an
actual loss of image data because the individual fields are improperly combined.
No field rendering Field rendering
Original image Blurred without field rendering