How do I use PCA

I have extracted features of an image,and stored in an folder,now i want to select best features from it using PCA AND have to comapre these features ,with the features of query image and retrieve it,please help

Answer 1

[Gautam]

Hello kash,

To perform feature selection using PCA, you can follow the MATLAB code below:

% Center the data
meanFeatures = mean(Features);
centeredFeatures = allFeatures - meanFeatures;

% Perform PCA
[coeff, score, ~, ~, explained] = pca(centeredFeatures);

% Select the number of principal components to retain (e.g., 95% variance)
cumulativeVariance = cumsum(explained);
numComponents = find(cumulativeVariance >= 95, 1);

% Reduce dimensionality
reducedFeatures = score(:, 1:numComponents); 

You can further use Euclidean distance to compare the query features with the stored features, and identify the closest matches