Given a $4 \times 4$ image, find the $4 \times 4$ lowpass filtered output using the $3 \times 3$ averaging filter with the borders periodically extended.
$$
x(m, n)=\left[\begin{array}{llll}
45 & 78 & 87 & 51 \\
59 & 56 & 62 & 49 \\
59 & 39 & 44 & 57 \\
56 & 36 & 35 & 51
\end{array}\right]
$$