uracy* and *speed*. Numerous feature
 types including histogram of gradients (hog) can be converted into
 channel features, and overall, channels are general and powerful.

 Given an input image I, a corresponding channel is a registered map of I,
 where the output pixels are computed from corresponding patches of input
 pixels (thus preserving overall image layout). A trivial channel is
 simply the input grayscale image, likewise for a color image each color
 channel can serve as a channel. Other channels 