# Is an image a random variable or a random process?

Is an image a random variable, where each pixel is a realization of the same random variable? Or is an image a collection of random variables (if an image is of size mxn, there are mxn distinct random variables)?

In the latter case, are the RVs (pixels) considered i.i.d. (even though they are not)?

So you can view a $m \times n$ image as a single random matrix (I assume this is what you mean by your first alternative - the image as a whole being considered as a single multidimensional random variable); or you can view it as a random field (a collection of random variables indexed by $|[1, M]| \times |[1, N]|$). I've encountered the random field view more often than the random matrix view.