- View the alpha on its own as black and white. Mistakes hide when you look at the colour comp.
- Put the cut-out over a bright red and then a bright green background to expose edge fringing.
- Scrub the fastest-moving section frame by frame. Matte errors cluster around motion blur.
- Fix the bad frames by hand rather than regenerating everything. Small manual paint-outs are quicker than another full pass.
Sources
Further reading from LTX. Read the original for full detail.