i want to generate four octaves of the original image. Each octave's image size is half the previous one. Within an octave, images are progressively blurred using the Gaussian Blur operator? kindly please help me.

clc;clear all;close all;
I=imread('parrot.jpg');
% figure;
% Im=imshow(uint8(I));
J = imresize(I, 0.5);
k=0;
sig=2;
for c=1:4;
    J = imresize(I, 0.5);
  for r=1:5;
    k=k+2;
G = fspecial('gaussian',[5 5],sig*k);
Ig = imfilter(I,G,'same');
figure;
imshow(Ig);
  end
end

[Walter Roberson]

http://www.mathworks.co.uk/matlabcentral/answers/43073-a-guide-to-tags