I seem to have it working now,
%%Correlation Test
image_file = 'Test3.bmp';
template_file = 'Test4.bmp';
image = (imread(image_file)); % set the image that is to be used
template = (imread(template_file)); % set the template that is to be used
%max_template = imrotate(template, -45, 'nearest', 'loose'); % find the maximum template size at 45 degrees
dim_image = [size(image, 1) size(image, 2)]; % store the dimensions of the image size
i = 1; % set i to 1
% find the maximum template size by cycling through each angle
for angle = 0:-20:-180,
rotate_template = imrotate(template, angle, 'nearest', 'loose'); % rotate template around specified angle -- without cropping
dim_rot(:, :, i) = ([size(rotate_template, 1) size(rotate_template,2)]); % store the dimensions of each rotation in array 'dim_rot'
i = i + 1; % increment 'i' each loop
end
dim_max = max(dim_rot,[],3); % find the values of the rotated template with maximum dimensions
correlation_matrix = zeros((dim_image(1) + dim_max(1) - 1), (dim_image(2) + dim_max(2) - 1), i-1); % set up the correlation matrix size (zeroed)
i = 1; % reset i to 1
for angle = 0:-20:-180,
rotate_template = imrotate(template, angle, 'nearest', 'loose'); % rotate template around specified angle -- without cropping
for k = 1:2,
state = mod(size(rotate_template, k), 2);
if state == 0,
if k == 1,
rotate_template(size(rotate_template, k), :) = [];
end
if k == 2,
rotate_template(:, size(rotate_template, k)) = [];
end
end
end
dim_rot_new = [size(rotate_template, 1) size(rotate_template, 2)];
rotate_template_new = padarray(rotate_template, [((dim_max(1) - dim_rot_new(:, 1))/2) ((dim_max(2) - dim_rot_new(:, 2))/2)], 0, 'both'); % pad 'rotate_template' array with zeros
correlation_matrix(:, :, i) = normxcorr2(rotate_template_new, image); % perform normalised cross colleration and store coefficient results in 'correlation_matrix'
figure(i);
subplot(1,2,1);
imshow(rotate_template);
title('Rotated Template');
subplot(1,2,2);
imshow(correlation_matrix(:,:,i));
title('Correlated Matrix');
i = i+1; % increment 'i' each loop
end
In the end I just deleted a column or row if the rotated template proved to be even. This would make the number of rows in the rotated template odd, and since the dimensions of the maximum template were always odd, this would allows for an even difference between:
"[((dim_max(1) - dim_rot(1))/2) ((dim_max(2) - dim_rot(2))/2)]"
in the padarray.
