使用Emgu cv进行后台替换

Question

I need to know that is there a method to remove the background of a live streaming web cam. There is a method called background Subtractor . If anyone knows to use that please help me out with the issue..

Answer 1

If you already have an image of the background you can just calculate

I - B

Where I is the Image and B is the background (of type say, Image)

B - I

Will also work.

Since images don't store negative numbers, you may wish to combine these both using

(I - B) + (B - I)

And convert the result to grayscale.

I method which I have found works better is to do this using fourier transforms.

ie:

F^-1(F(I) - F(B))

for example

    CvInvoke.cvDFT(video.Convert<Gray, Single>().Ptr, DFT.Ptr, Emgu.CV.CvEnum.CV_DXT.CV_DXT_FORWARD, -1);
    CvInvoke.cvDFT(Background.Convert<Gray, Single>().Ptr, DFTBack.Ptr, Emgu.CV.CvEnum.CV_DXT.CV_DXT_FORWARD, -1);

    CvInvoke.cvDFT((DFTBack - DFT).Convert<Gray, Single>().Ptr, originalLeft.Ptr, Emgu.CV.CvEnum.CV_DXT.CV_DXT_INVERSE, -1);
    CvInvoke.cvDFT((DFT - DFTBack).Ptr, originalRight.Ptr, Emgu.CV.CvEnum.CV_DXT.CV_DXT_INVERSE, -1);

This works well when the foreground is partially translucent.

There's also the built in Foreground detector