Further clean up after roto brush and refined edge tool

[dmkAlex]

I use roto brush to pick out a subject (a flower) from the background. The flower is white and there is a sign behind it that I want to hide. The roto brush and the refine edge did a good job in picking out the white subject.

But the sign had a little white rim right behind the flower. Both tool don't seem to distinguish it from the white flower.

How do you further clean up the mask selection after using these tools?

[Rick Gerard]

Rotobrush needs to be frozen when you are done. Most of the time the matte is not perfect. There are a couple of ways to clean up the matte. It is usually best not to do masking or apply additional effects to the rotobrush layer. Probably the easiest solution is to add a colored solid above the footage, set the blend mode to something like add or screen and adjust the color so you can see through the layer and there is good contrast with the subject. Then you manually rotoscope the flaws out using masks. The advantage of working on a layer with a blend mode so you can see through it is that you can get a good look at the edges. In most cases, only a small part of the mask needs to be accurate. When the mask is done just set the layer as a track matte for the original footage.

Another approach is to pre-compose the Rotobrush layer after freezing and then do your roto work on the pre-comp. I don't usually use this method because it's really difficult to get a real good look at the edges when you are masking directly on a layer.

Most of the time there are just a few frames that need fixing so make sure you are not spending time doing hand roto on frames that don't need it. Sometimes you can throw in additional techniques like Motion Stabilizing to help make the job easier. The most efficient solution depends entirely on the shot.

If these suggestions don't help we probably need to see a screenshot of the footage that shows us the problem.

Here's a short video I did a long time ago that shows the track matte technique of doing hand roto. Maybe it will give you some ideas: