title: Gesture recognition using hidden markov model
body: <p>I am currently working on a Gesture Recognition application, using a Hidden Markov Model as the classification stage on matlab(using webcam). I've completed the pre-processing part which includes extraction of feature vector. I've applied Principal Component Analysis(PCA) to these vectors.</p>
  
  <p>Now for me to use Kevin Murphy's HMM toolbox, I need my observation sequence to be in the form of numbers(integers) ranging from 1 to M (M = number of observation symbols). If I'm correct then I have to use the concept of a codebook and use vector quantization to get my observation sequence.</p>
  
  <p>My questions:</p>
  
  <ol>
  <li>How do I build a codebook?</li>
  <li>And How do I use this codebook to obtain the observation symbols of my input video?</li>
  </ol>
  
  <p>Note: I've used Elliptical Fourier descriptors for shape feature extraction and for each gesture the PCA values are stored in a matrix of dimension [11x220] (Number of frames in the video = 11)</p>
  
  <p>What do I do next?
  Is there any other way to obtain feature vectors instead of Elliptical Fourier descriptors?</p>