histcImLoc

 Creates a series of locally position dependent histograms.

 Inspired by David Lowe's SIFT descriptor.  Takes I, divides it into a
 number of regions, and creates a histogram for each region. I is divided
 into approximately equally sized hyper-rectangular regions so that
 together these hyper-rectangles cover I.  The hyper-rectangles are
 actually 'soft', in that each region is actually defined by a gaussian
 mask, for details see maskGaussians. parMask, parameters to
 maskGaussians, controls details about how the masks are created.
 Optionally, each value in I may have associated weight given by wtMask,
 which should have the same exact dimensions as each channel of I.

 If multCh is set to true, then:
  I is an [M1xM2x...xMkxnd] array of nd channels
 otherwise
  I is an [M1xM2x...xMk] array of 1 channel
 If nd==1, histcImLoc creates a 1D histogram using histc2.  More
 generally, histcImLoc creates an nd dimensional histogram (again using
 hist2c).  histcImLoc creates nMasks (number of masks) histgorams, each
 which have dimension nBins^nd.  So if nd==1 the output of this function
 is [nBins x nMasks], and for example if nd==2 the output is [nBins x
 nBins x nMasks].  If nd is large computing the histograms is time
 consuming.

 USAGE
  h = histcImLoc( I, edges, parMask, [wtMask], [multCh] )

 INPUTS
  I           - M1xM2x...xMkxnd array, (nd channels each of M1xM2x...xMk)
  edges       - quantization bounds, see histc2
  parMask     - cell of parameters to maskGaussians
  wtMask      - [] M1xM2x...xMk numeric array of weights
  multCh      - [0] if 1 last dimension of I is number of channels

 OUTPUTS
  h           - nd-histograms [nBins^nd x nMasks]

 EXAMPLE - multCh==0
  I = filterGauss([100 100],[],[],0);
  h = histcImLoc(I,10,{2,.6,.1,1},[],0);
  figure(1); im(h)

 EXAMPLE - multCh==1
  I = filterGauss([100 100],[],[],0);
  h1 = histcImLoc( cat(3,I,I), 10, {2,.6,.1,0},[],1);
  h2 = histcImLoc( cat(3,I,randn(size(I))),10,{2,.6,.1,0},[],1);
  figure(1); montage2(h1); figure(2); montage2(h2);

 See also HISTC2, MASKGAUSSIANS, ASSIGNTOBINS, HISTCIMWIN

 Piotr's Computer Vision Matlab Toolbox      Version 2.0
 Copyright 2014 Piotr Dollar.  [pdollar-at-gmail.com]
 Licensed under the Simplified BSD License [see external/bsd.txt]