% Pyramid = GuassianPyramid(img, levels)%% Computes a gaussian pyramid of the given number levels.% The image is downsampled by 2 in each level. Before downsampling an% antialiasing filter using a kernel: [1 4 6 4 1]/16 is performed.%% Inputs:% img - The base image of the highest level in the pyramid% levels - The number of levels to be used. The parameter is optional.%                     A default level of 4 will be used of parameter is%                     ignored.% Outpus:% A cell array  of images. Index 1 will include the input img. Index% k=levels will include the lowest resolution image.function pyramid = GuassianPyramid(img, levels)if nargin<2  levels=4;end% Initialize pyramidpyramid{1}=img;% Build pyramidfor i=2:levels  pyramid{i}=GaussianDownSample(pyramid{i-1});end