very low score similarity in pca

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primrose khaleed
primrose khaleed 2014-6-1
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
  2 个评论
primrose khaleed
primrose khaleed 2014-6-2
编辑：primrose khaleed 2014-6-2
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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