MATLAB: How to use classification after PCA(dimensionality reduction)

classificationdatadata importdimensionality reductionpcarecognition

Hello.

I want to classify videos.

The original data : 25290 x 25

After applying dimensionality reduction like PCA, I got this data.

The reduced data : 2 x 25

Is it resonable to use these reduced data for classification?

I got low accuracy of classification. Could you give some ideas to solve it?

Best Answer

Don't use PCA for dimentionality reduction or feature selection in case of videos or images. Instead use some feature extraction techniques in images like HOG features, sift features, optical flow(for videos), etc. Since the datapoints are very less(assuming 25 datapoints), you could use some data augementation techniques for videos.

For example, crop some random sequence from the video for temporal augmentation then use Image augmentation for each frame.

For Image augmentation, you can refer to documentation here: https://www.mathworks.com/help/deeplearning/ref/imagedataaugmenter.html

Hope it helps !!! :)

Related Solutions

MATLAB: PCA (dimension reduction) in embedded matlab

for i = 1 : 22
  for a = 1 : 12
      if (i == req_idx(a))
          for j = 1 : 22
              Y_dr(i,j) = Y(i,j);
          end
      else
          for k = 1 : 22
              Y_dr(i,k) = 0;
          end
      end
  end
end

I have written the code as shown above and have used the sort function to get the principal components which gives an ascending or descending order but I need the 'req_idx' variable to be in appropriate order.

Kindly Help !

MATLAB: How to video classification using feature extraction

For video classification, you can use CNN for extracting spatial features. CNN is capable to extract deep features that HOG and other handcrafted feature extraction techniques might not be albe to. Use LSTM for capturing temporal features beacause you also need to have some sequential information between frames in a video.

You can read about CNN and LSTM in links here :

https://www.mathworks.com/solutions/deep-learning/convolutional-neural-network.html

https://www.mathworks.com/help/deeplearning/ug/long-short-term-memory-networks.html

Best Answer

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MATLAB: PCA (dimension reduction) in embedded matlab

MATLAB: How to video classification using feature extraction

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