s x 1] struct array
     .name       - channel type name
     .pChn       - exact input parameters for given channel type
     .nChns      - number of channels for given channel type
     .padWith    - how channel should be padded (0,'replicate')

 EXAMPLE - default channels
  I=imResample(imread('peppers.png'),[480 640]); pChns=chnsCompute();
  tic, for i=1:100, chns=chnsCompute(I,pChns); end; toc
  figure(1); montage2(cat(3,chns.data{:}));

 EXAMPLE - default + custom channels
  I=imResample(imread('peppe