目标检测 IOU 计算

Posted by wxianfeng Mon, 03 Mar 2014 07:13:00 GMT

iou 为面积的交并比,在目标检测中非常常见,英文为 Intersection-over-Union。

图示:

计算格式:

python 代码:

class IOU:

    def calc_iou(self, bbox1, bbox2):
        """
        calc iou
        :param bbox1: (x1,y1,x2,y2)
        :param bbox2: (x1,y1,x2,y2)
        :return:
        """
        w_1 = abs(bbox1[0] - bbox1[2])
        h_1 = abs(bbox1[1] - bbox1[3])
        area_1 = w_1 * h_1

        w_2 = abs(bbox2[0] - bbox2[2])
        h_2 = abs(bbox2[1] - bbox2[3])
        area_2 = w_2 * h_2

        min_x_1 = min(bbox1[0], bbox1[2])
        min_y_1 = min(bbox1[1], bbox1[3])
        max_x_1 = max(bbox1[0], bbox1[2])
        max_y_1 = max(bbox1[1], bbox1[3])

        min_x_2 = min(bbox2[0], bbox2[2])
        min_y_2 = min(bbox2[1], bbox2[3])
        max_x_2 = max(bbox2[0], bbox2[2])
        max_y_2 = max(bbox2[1], bbox2[3])

        overlap_min_x = max(min_x_1, min_x_2)
        overlap_min_y = max(min_y_1, min_y_2)
        overlap_max_x = min(max_x_1, max_x_2)
        overlap_max_y = min(max_y_1, max_y_2)

        overlap_w = max(0, overlap_max_x - overlap_min_x)
        overlap_h = max(0, overlap_max_y - overlap_min_y)
        overlap_area = overlap_w * overlap_h

        iou = overlap_area / (area_1 + area_2 - overlap_area)

        return iou

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