Videomaker – Learn video production and editing, camera reviews › Forums › Technique › Editing › Make subject color, and background black and white. › If you have already filmed
If you have already filmed your footage, and don’t mind taking a good amount of time, you can accomplish this effect using AE. Create an adjustment layer, desaturate, then make a mask over your person. The background will have no color, while everything in your mask will be unaffected.
However, the greenscreen way will save you lots of time and frustration.