Error while using PCA for image recognition?

Hello!

I've used this code for image recognition using PCA. I keep getting this error:

Error using  -   
Integers can only be combined with integers of the same class, or scalar doubles.

Error in pirnccompanal (line 43)
feature_vec = evectors' * (input_image(:) - mean_face);

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Can someone tell me what is wrong with the code? All the images used have dimensions of 60x60. gest1Cell is a cell of 30 images in grayscale (60x60).

Thank you for your time!

clc;
clear all;

gestdatabase;

input_image = gest1Cell{25};

images = [];
image_dims = [60, 60];
num_images = 30;

for n = 1:30

      img = gest1Cell{n};
      if n == 1
          images = zeros(prod(image_dims), num_images);
      end

      images(:, n) = img(:);

end

% TRAINING

% steps 1 and 2: find the mean image and the mean-shifted input images
mean_face = mean(images, 2);
shifted_images = images - repmat(mean_face, 1, num_images);

% steps 3 and 4: calculate the ordered eigenvectors and eigenvalues
[evectors, score, evalues] = pca(images');

% step 5: only retain the top 'num_eigenfaces' eigenvectors (i.e. the principal components)
num_eigenfaces = 20;
evectors = evectors(:, 1:num_eigenfaces);

% step 6: project the images into the subspace to generate the feature vectors
features = evectors' * shifted_images;

% TESTING AND CLASSIFICATION

% calculate the similarity of the input to each training image
feature_vec = evectors' * (input_image(:) - mean_face);
similarity_score = arrayfun(@(n) 1 / (1 + norm(features(:,n) - feature_vec)), 1:num_images);

% find the image with the highest similarity
[match_score, match_ix] = max(similarity_score);

% display the result
figure, imshow([input_image reshape(images(:,match_ix), image_dims)]);
title(sprintf('matches %s, score %f', filenames(match_ix).name, match_score));

[suchetha n]

For calculating similarity score which method is used?

Answer 1

[Image Analyst]

Try casting everything to double before doing the math.