how to remove background image and get fore image

Question

there are two images

alt text http://bbs.shoucangshidai.com/attachments/month_1001/1001211535bd7a644e95187acd.jpg alt text http://bbs.shoucangshidai.com/attachments/

Answer 1

One technique that I think is common is to use a mixture model. Grab a number of background frames and for each pixel build a mixture model for its color.

When you apply a frame with the person in it you will get some probability that the color is foreground or background, given the probability densities in the mixture model for each pixel.

After you have P(pixel is foreground) and P(pixel is background) you could just threshold the probability images.

Another possibility is to use the probabilities as inputs in some more clever segmentation algorithm. One example is graph cuts which I have noticed works quite well.

However, if the person is wearing clothes that are visually indistguishable from the background obviously none of the methods described above would work. You'd either have to get another sensor (like IR or UV) or have a quite elaborate "person model" which could "add" the legs in the right position if it finds what it thinks is a torso and head.

Good luck with the project!