How to save images with same resolution when using set() function?

According to code below, both of my inputs are size 250X250. But the code fail to get me output of same size as inputs.

E = rgb2gray(imread('nofill.png'));
imshow(E, 'InitialMag', 'fit')

I = rgb2gray(imread('black.png'));
imshow(I, 'InitialMag', 'fit')

imshow(E, 'InitialMag', 'fit')
% Make a truecolor all-green image.
green = cat(3, zeros(size(E)),ones(size(E)), zeros(size(E)));
hold on;
h = imshow(green);
hold off

% Use our influence map as the
% AlphaData for the solid green image.
set(h, 'AlphaData', I)
imwrite(
%  print('test','-dpng')

[Walter Roberson]

Your imwrite() appears to have gotten corrupted in the posting.