Background subtracting in MATLAB

Question

I\'m looking to do background subtracting on an image. I\'m new to MATLAB and new to image processing/analysis, so sorry if any of this sounds stupid. 1) Other than

Answer 1

To subtract the background image, you need a model of the background. The simplest model is an image captured as the background along with some allowable deviation (+/- 0-255). Then, background subtraction in MATLAB is pretty simple:

image( find(abs(image-background) <= threshold) ) = 0;

It becomes more difficult when you use a statistical model, but essentially subtracting the background is pretty easy. imsubtract is NOT background subtraction; it is a subtraction filter like you would find in photoshop. It does not care about background versus foreground, which then defeats the point.

Since background subtraction itself is pretty easy, the question becomes more about background estimation. This is a bit more complicated, and generally requires more frames and training to build statistical models of the background (for example, looking at pixels as Gaussian distributions or mixtures of Gaussians, or looking instead at optical flow to determine what's not moving).

If you have access to technical articles (via work or school), "Pfinder: Real-Time Tracking of the Human Body" by Wren and others gives a pretty simple approach. Or you can just search google for single Gaussian background subtraction. There are a number of methods implemented with OpenCV here --> http://dparks.wikidot.com/source-code <-- that you might find useful.