Filtering Image with Sampled Array

I have an image that I want filtered so that only certain portions of the image show (e.g. a non-uniform checkerboard like pattern will be the result). I have the points that I want to be visible given in a sampled grid formed by two vectors, X (which is 1xM) and Y (which is 1xN). These vectors result in a plot with a lower spatial frequency due to the sampling. How can I create a filter that only displays a QxQ grid around each of the points of interest saved in the X,Y vectors?

For example, show a only 5x5 box around each white point in the image http://i.imgur.com/j1aMt.jpg?