MATLAB: Undefined function or variable ‘map’ Error. How to fix

fftfft2patternperiodic

After working on this for a few days. This is the code I've written thus far:
if true
  % code
end
% Clear the workspace
clc
clear all;
% Read the image 'Proj2.tif'
Proj2Image = 'Proj2.tif';
img = imread(Proj2Image);
% Stores the image as an array
img = img(:,:,1);
% I then take the Fast Fourier Transform (FFT) of the Image
imgfft = fft2(img);
% Next, I create a Butterworth Filter. A Low Pass Filter
% could probably also be performed, and work just as well.
% Note: C is a constant
%       X is the size of the dimension of array X
%       Y is the size of the dimension of array Y
c = 2;
X = size(imgfft, 1);
Y = size(imgfft, 2);
% A returns an array of ones in the X and Y direction
A = ones(X,Y);
XX = [204 182 191 196 214 219 228];
YY = [273 275 267 282 264 279 271];
% L is the max number of pixels in the image (i.e. 255)
L = 255;
for i=1:length(L)
 for x = 1:X
    for y = 1:Y
    %Compute the distance between the points.
    Lxy = sqrt((x-XX(i))^2 + (y-YY(i))^2);
    A(x,y) = A(x,y) + 1/(1+(Lxy/L(i)^2))^(2*c);
    end
 end;
end;
% Subtract the array of ones
A = 1 - A;
% Next, I apply the filter by shifting the FFT of the image
% and multiplying it by the array of ones.
FilterImage = fftshift(imgfft).*A;
% Here, I shift back and perform the Inverse FFT
FilterImage2 = ifft2(fftshift(FilterImage));
% Next, I display FilterImage2 with the colormap defined as 'map'
imshow(abs(FilterImage2),map);
% Then I resize and display the 'periodicpattern.tif' image
% And compare it to the 'Proj2.tif' image that I filtered,
% shifted, and performed the FFT and Inverse FFT on.
[img,map] = imread('periodicpattern.tif');
figure('Name','Patterns/comparison');
subplot(1,2,1), imshow(abs(FilterImage2),map);
title('Patterns');
subplot(1,2,2), imshow(img,map);
title('Periodic Pattern of Image');
The problem I have with this code though is that when I run it, I get the following error message on Line 63: Undefined function or variable 'map'.
Do you have any other method I could use to fix this error, other than:
imshow(abs(FilterImage2),map);
I'm not quite too sure why it is doing this since Matlab ought to accept:
imshow(X,map)
which I don't think is all that much different. I tried replacing the abs(FilterImage2) by assigning it to a variable called I:
I = abs(FilterImage2);
But Matlab doesn't like this either.
Again, my input image is attached and all I am trying to do with it is get the mesh periodic cross-pattern out of it.

Best Answer

Michael, you need to change line 9 from
img = imread(Proj2Image);
to
[img,map] = imread(Proj2Image);
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