 for gradient magnitude:
     .enabled      - [1] if true enable gradient magnitude channel
     .colorChn     - [0] if&gt;0 color channel to use for grad computation
     .normRad      - [5] normalization radius for gradient
     .normConst    - [.005] normalization constant for gradient
     .full         - [0] if true compute angles in [0,2*pi) else in [0,pi)
   .pGradHist    - parameters for gradient histograms:
     .enabled      - [1] if true enable gradient histogram channels
     .binSize      - [sh