In this exercise, we consider the total variation image inpainting problem min (1) CERma | Ax - b3 + -IDx3 that was discussed in the lectures. Here, c = vec(X ) corresponds to a vectorized image X e Rmxn A ( RXmn is a selection matrix that selects pixels according to a given inpainting mask, and b E R$ contains the undamaged image information. The matrix D = (D); e Ramnxma stacks all of the discretized image gradients Dog in a large 2mn x mn matrix and a > 0 is a given regularization parameter. Show that a point