I'm trying to cluster MNIST dataset, I'm using PCA(for dimension reduction) and kmeans for clustering. For now I'm using just raw vector of pixels, I tried to convert it with Local Binary Patterns but it still gives bad results, I think I need to compute histograms based on LBP, but not sure how. I use code from here
can you provide some examples?
First try to apply a PCA directly, I think it's sufficient already. Then note, that mathematically a k-means method yields the same centroids as a PCA projection, see:
So there's no need to perform a k-means clustering on the projected samples. What I would try instead is to see, what clusters a Linear Discriminant Analysis yields. A Linear Discriminant Analysis is available as cv::LDA in the contrib module of OpenCV:
Then I would play around with OpenCV's awesome machine learning library and see how a Multi Layer Perceptron performs or how a SVM performs on the image data (with different kernels).
Regarding Local Binary Patterns, there's a much simpler (and tested!) implementation in the face recognition code I provide. The OpenCV implementation in cv::FaceRecognizer is the same. I am linking to the original project (libfacerec), because everything is in one file there:
If you need some ideas on how to work with OpenCV machine learning, you can have a look into my Guide to Machine Learning with OpenCV:
There are also tutorials on using a SVM in the official OpenCV documentation:
by kmeans I cluster unlabled data(for example I have 10 classes(0-9 digits) and cluster to 30 clusters and then I see this clusters and maybe merge some if they are similar) and PCA just give basic(for reduce dimensions), so I don't know how to use PCA for clustering.For testing preprocessing before PCA I project all data to 2D and see how is data separable(for that propose I use labels), for example I tried separable histograms that was in pack with LBP for preprocessing thresholded binary digits.
at last I want to achive something like that http://homepage.tudelft.nl/19j49/t-SNE_files/mnist_large.jpg but now I have something like that http://www.compvision.ru/forum/index.php?app=core&module=attach§ion=attach&attach_rel_module=post&attach_id=740
Asked: 2012-08-21 06:24:53 -0600
Seen: 1,698 times
Last updated: Aug 21 '12
