[ladberg]

Even if you never matrix multiply with an image, it's still useful to have it in matrix form for other things like PCA/SVD.

[newen]

Typical use on PCA/SVD on image, what you do is treat each image as a vector, create a matrix out of a collection of images, and then do PCA/SVD on the matrix to analyze the distribution of the images, normalize, get the eigen-images (principal components), etc.

[ladberg]

Yeah, in retrospect that seems like the way to do it. The toy examples I learned from in college did it on a single image split up by row, but I can’t think of a great use case for that besides some naive compression.