MATLAB: How to calculate dimension using PCA

dimensionality reductionfeature extractionpca

Hello.

I want to classify videos.

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

The original data : 25290 x 25

The reduced data : (2~25) x 25

I can't reduce data more 25 dimension.

I want to get more dimension like (50 x 25), (100 x 25), (100 x 25), etc.

However, the dimension is reduced until 25 x 25. Could you explain this problem?

Best Answer

You can specify the number of components you require while applying PCA using 'NumComponents' option.

Have a look here.

Related Solutions

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

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 !!! :)

MATLAB: PCA values

Eigenvectors are a little arbitrary. If A is a matrix and b is one of its eigenvectors, then so is b multiplied by any scalar. In particular, if

A*b = e*b

for some eigenvalue e, then

A*(-b) = e*(-b).

Best Answer

Related Solutions

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

MATLAB: PCA values

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