DirectShow Video Overlay filter

i need a filter that will attach to video ca pture cards that will allow me to choose a static bitmap and when the video capture pin is connected to this static bitmap, it will overlay the person on the video capture overtop the static bitmap. the media type going into the filter must have the same in its output. the only difference is the actual stream has the overlay person and the static image going out, so it can connect to stuff such as video render, wmv writer, and other filters. for example there are tons of apps that put a background and take a snapshot of a person and overlays that person on top of the background. and it cancels out the background in the snapshot of the person so it only gets the person. so it overlays nicely on top of the background. this is what i want the directshow filter to do. but it will be video which is just a series of snapshots at the set framerate. so the captured video should make background transparent just showing the person then superimpose or overlay that atop the background static image then push it out the outpin feel free to use intels openCV if you need to