bbox鏡像數據增強

def random_flip(img):
    img = img[:, ::-1, :]
    return img


def flip_bbox(bbox, size):
    H, W = size
    bbox = bbox.copy()
    x_max = W - bbox[:, 0]
    x_min = W - bbox[:, 2]
    bbox[:, 0] = x_min
    bbox[:, 2] = x_max
    return bbox