Background subtraction marks shadows as foreground

Question

I've got background subtraction to work quite well. But the problem is, it marks shadows as foreground as well.

Has anyone found some technique to get rid of shadows from the background? Links to techniques, papers, articles, etc you've used and got reliable will be awesome!

Answer 1

This is a well known problem, and like many well known problems, there has been a lot of research into it, meaning there is no real "optimal" solution.

Google Scholar suggests many papers for dealing with the problem. The works of Elgammal, Davis et al. are a good place to start.

You may also be interested in a more recent work on Detecting Ground Shadows in Outdoor Consumer Photographs.

Answer 2

Nice papers:

N. Martel-Brisson, A. Zaccarin, “Moving Cast Shadow Detection from a Gaussian Mixture Shadow”, International Conference on Computer Vision and Pattern Recognition, CVPR 2005, San Diego, CA, USA, June 2005.

N. Martel-Brisson, A. Zaccarin, “Moving Cast Shadow Detection from a Gaussian Mixture Shadow Model: A step toward robust detection and segmentation algorithms in computer vision”, Annual Canadian Conference on Intelligent Systems, IS 2006, Victoria, B.C., May 2006.

N. Martel-Brisson, A. Zaccarin, “Learning and Removing Cast Shadows through a Multidistribution Approach”, Transactions on Pattern Analysis and Machine Intelligence, Volume 29, No. 7, pages 1-13, July 2007.

C. Huang, R. Wu, “An Unsupervised Shadow Detection Algorithm”, International Computer Symposium, ICS 2008, 2008.

C. Huang, R. Wu, “An Online Learning Method for Shadow Detection”, Pacific-Rim Symposium on Image and Video Technology, PSIVT 2010, Singapore, Singapore, November 2010.

Best regards! Thierry

Answer 3

This is a great paper. You can find every thing about various state of the art background subtraction algorithms:

A comprehensive review of background subtraction algorithms evaluated with synthetic and real videos

In the section 4.3.4.3. of this paper you can see comparison between algorithms when they encounter with different degree of shadow in test video. As a quick conclusion, MultiLayerBGS algorithm outperforms other methods in test cases with considerable amount of shadow.

You can find good implementation of this method and more than 35 background subtraction methods by Andrew Sobral in this page.