Scale-space pyramids

  Write an m-file "scale_space.m" which computes scale space representation of an input image for a given scale "sigma" and displays them.

(i) 4 scale levels, all the levels have the same size.

function scale_space(imn, sigma)

s=sigma;
figure(1);
imshow(imn,[]);
for i=1:3
  g=gauss(s);
  imgx=?
  imgxy=?
  s=?
  figure(i+1);
  imshow(imgxy,[]);

end

(ii) 4 scale levels, every next level is twice smaller than the previous one.
To sample the image use:
imn=imgxy(1:sampling_step:end,1:sampling_step:end);
Choose the sampling_step.

Discuss these representations.
How do they differ? Are they equivalent? Which one is more suitable? Why?