 have proven the most effective for sliding window object detection):
  (1) color channels (computed using rgbConvert.m)
  (2) gradient magnitude (computed using gradientMag.m)
  (3) quantized gradient channels (computed using gradientHist.m)
 For more information about each channel type, including the exact input
 parameters and their meanings, see the respective m-files which perform
 the actual computatons (chnsCompute is essentially a wrapper function).
 The converted color channels serve as input to gr