Algorithm 1: Blurred Degree Calculation with SIGD

Input: Image $g(u,v)$, Gradient threshold B  Output: Blurred degree b 1 Detect M and N of $g(u,v)$ 2 Convert $g(u,v)$ to YUV color space, construct $g_Y(u,v)$ 3 For each pixel in $g_Y(u,v)$, calculate its $\Delta g_Y(u,v)$ 4 Calculate blurred degree b of $g_Y(u,v)$ by Formulas (3) and (4)