Tuesday, January 3, 2012

The constraints of histogram tracking

While in the last months I have implemented and tested a couple of histogram based tracking algorithms I only recently realized their inherent constraints. If you use it for hand tracking and you have your arms naked or your face exposed it is very easy for the tracker to get confused because of the coarse quantization of the histograms.
The worst part is that there is little you can do :
  • I tried using a different color space such as HSV. While it is far better that RGB for tracking skin and coping for small lighting variances it is still not enough and the tracker often gets confused especially when the hand goes out of view.
  • I tried incorporating different features such as edge magnitude (bad idea) and edge orientation (much better) and it had the effect of better localizing the detector. 
Integral histograms are still an option but there are far too slow for a real time application like the one I'm working on.