I want to draw Hadamard matrices of different sizes. This are matrices which have entries +1 and -1 (plus some other properties). Hadamard matrices are often pictured as black/white grids like
I'm looking for a simple way to draw them with LaTeX. That means there is an input file consisting of +/-1's (or other values, if this is more helpful). LaTeX should convert it to a b/w grid. And it would be nice if I could enter a size for the whole grid and it does automatic resizing. Like in the pictures above.
