gradient.m

Gradient code. Use this to do gradient of image.

function[im_gradient] = gradient(im)

   %%% LOWPASS AN DERIVATIVE FILTER
   p = [0.037659 0.249153 0.426375 0.249153 0.037659];
   d = [0.109604 0.276691 0.000000 -0.276691 -0.109604];

   %%% COMPUTE GRADIENT
   [ydim,xdim,zdim] = size( im );
   for z = 1 : zdim
      im_x = conv2( conv2( im(:,:,z), d, 'same' ), p', 'same' );
      im_y = conv2( conv2( im(:,:,z), p, 'same' ), d', 'same' );
      im_g = sqrt( im_x.^2 + im_y.^2 );
      im_gradient(:,:,z) = im_g;
   end