Gray Out
The Gray Out effect transforms all colors of the picture to the gray part of the spectrum and only one color (you select) will appear.
In the Properties Area of the Video Effect window you can change the effect propertieschange the effect properties.
Here you can select a certain color to be appeared, to modifiy Threshold and Filter values.
In the figures below you can see the video picture before and after applying the Gray Out effect:
Before applying the Gray Out effect
After applying the Gray Out effect