“…For the k anchors, the anchor point is located in the centroid of the sliding window, anchors are bounding boxes that have three different sizes (128 × 128, 256 × 256, and 512 × 512) and three different aspect ratios (0.5, 1, and 2), thus k = 9, and the width and height of anchors are determined by Equation (1) W i, j = 2 s j × round( (x × y)/r i ) H i,j = 2 s j × round(round( (x × y)/r i ) × r i ) (1) where W, H represent the width and height of an anchor; r i = (r 1 , r 2 , r 3 ) = (0.5, 1, 2), and r i indicates the aspect ratio; s j = (s 1 , s 2 , s 3 ) = (3,4,5), and 2 s j indicates the expansion factor of size; round stands for rounding; and x, y indicate the width and height of pixels of a feature point mapped back to the original input image, and x = y = 16.…”