very low score similarity in pca

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primrose khaleed 2014-6-1

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/132022-very-low-score-similarity-in-pca

编辑： primrose khaleed 2014-6-2

 hi everybody...i used pca to get similarity between images ..the problem is the score is very
low when enter the images to compering with the images in files
this is code

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] = princomp(images');

% step 5: only retain the top 'num_eigenfaces' eigenvectors (i.e. the principal components) num_eigenfaces = 2; evectors = evectors(:, 1:num_eigenfaces);

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

%%%%%%%%%%%%%%%%praper input imag%%% img3 = rgb2gray(imread('777.jpg'));

background = imopen(img3,strel('disk',15)); img3 = imabsdiff(img3,background);%strel,Create morphological structuring element (STREL)

myfilter = fspecial('gaussian',[5 5], 0.5);
myfilteredimage = imfilter(img3, myfilter, 'replicate');
%nois=imnoise(myfilteredimage,'salt & pepper');
medf= medfilt2(myfilteredimage,[8 8]);

%%%%%%%%%%%%%%%%%

se = strel('disk',4); img4 = edge(medf,'canny',0.08); img4= bwareaopen(img4,30);

input_image = imclose(img4,se); %closeBW=imfill(closeBW,'holes'); input_image=imresize(input_image,[80, 70]);

%%%%%%%%%%%%%%%%%%classifcation

% calculate the similarityty 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));

my quetions : why the score is very very low..(score =.0032)??? >how to specify the num_eigenfaces..(principal components, which is set by the variable num_eigenfaces)??? >>when decrease the num_eignface the score increase (why)??

plz help me

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Image Analyst 2014-6-2

Haven't I ever asked you to read this before? If not, here it is again http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

primrose khaleed 2014-6-2

编辑：primrose khaleed 2014-6-2

在 MATLAB Online 中打开

i used this code to get the features and get similarty between input images with images that stores in files:

 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] = princomp(images');
% step 5: only retain the top 'num_eigenfaces' eigenvectors (i.e. the principal components)
num_eigenfaces = 70;
evectors = evectors(:, 1:num_eigenfaces);
    % step 6: project the images into the subspace to generate the feature vectors
features = evectors' * shifted_images;
    % calculate the similarityty 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));

my quetions : why the score is very very low..(score =.0032)??? >how to specify the num_eigenfaces..(principal components, which is set by the variable num_eigenfaces)??? >>when decrease the num_eignface the score increase (why)??

plz help me

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