Given a $4 \times 4$ image, find the $4 \times 4$ lowpass filtered output using the $3 \times 3$ Gaussian filter ( $\sigma=0.5$ ) with the borders periodically extended.
$$
x(m, n)=\left[\begin{array}{llll}
202 & 195 & 192 & 191 \\
216 & 211 & 200 & 209 \\
224 & 212 & 215 & 227 \\
224 & 205 & 227 & 230
\end{array}\right]
$$