% EE 438 Digital Signal Processing with Applications - Spring 2001
% 2-D signals and systems
% Image display within Matlab
%---------------------------------------------------------------
% Initialize
clear all;
close all
%---------------------------------------------------------------
%Initialize colormap
mcomp = 0 : 1.0 ./ 255 : 1.0; % output colors lie in [0,1]
map = [mcomp' mcomp' mcomp'];
M = 8;  % size of image
M2 = M/2;
X = 6;  % width of rect
X2 = X/2;
rect1d = zeros(M,1);
rect1d(M2-X2+1:M2+X2) = ones(X,1);
f=rect1d*rect1d';
h=[ 0 -.5 0 ; 0.5 1 0.5 ; 0 -.5 0];
g=conv2(f,h);
%figure(1);
%image(g*255);
%colormap(map);
%axis('off');
%axis('image');
%g = fftshift(g);
H = fft2(h,256,256);
H = fftshift(H);
Hmag = abs(H);
Hmax = max(max(Hmag));
decade = 2;
Hmag = Hmag/Hmax*10^decade+1;
Hmag = log10(Hmag);
Hmax = max(max(Hmag));
%figure(2);
image(Hmag*255/Hmax);
colormap(map);
axis('off');
axis('image');