title: 2-D convolution as a matrix-matrix multiplication
body: <p>I know that, in the 1D case, the convolution between two vectors, <code>a</code> and <code>b</code>, can be computed as <code>conv(a, b)</code>, but also as the product between the <code>T_a</code> and <code>b</code>, where <code>T_a</code> is the corresponding Toeplitz matrix for <code>a</code>.</p>
  
  <p>Is it possible to extend this idea to 2D?</p>
  
  <p>Given <code>a = [5 1 3; 1 1 2; 2 1 3]</code> and <code>b=[4 3; 1 2]</code>, is it possible to convert <code>a</code> in a Toeplitz matrix and compute the matrix-matrix product between <code>T_a</code> and <code>b</code> as in the 1-D case?</p>