如何解决OpenCV(4.6.0)中rectangle函数的(-5:Bad argument)错误？

研究实例分割模型，训练完成后推理时遭遇OpenCV(4.6.0)的rectangle函数报错，错误类型为(-5:Bad argument)，尝试将boxes[i][0]转换为int类型后问题仍存在，相关代码及错误详情如下：

相关代码 #

def get_prediction(img_path, confidence):
    
    img = Image.open(img_path)
    transform = transforms.ToTensor()
    img = transform(img)
    img = img.to(device)
    pred = model([img])
    pred_score = list(pred[0]['scores'].detach().cpu().numpy())
    pred_t = [pred_score.index(x) for x in pred_score if x>confidence][-1]
    masks = (pred[0]['masks']>0.5).squeeze().detach().cpu().numpy()
    # print(pred[0]['labels'].numpy().max())
    pred_class = [CLASS_NAMES[i] for i in list(pred[0]['labels'].cpu().numpy())]
    pred_boxes = [[(i[0], i[1]), (i[2], i[3])] for i in list(pred[0]['boxes'].detach().cpu().numpy())]
    masks = masks[:pred_t+1]
    pred_boxes = pred_boxes[:pred_t+1]
    pred_class = pred_class[:pred_t+1]
    return masks, pred_boxes, pred_class

def segment_instance(img_path, confidence=0.5, rect_th=2, text_size=2, text_th=2):

    masks, boxes, pred_cls = get_prediction(img_path, confidence)
    img = cv2.imread(img_path)
    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    for i in range(len(masks)):
      rgb_mask = get_coloured_mask(masks[i])
      img = cv2.addWeighted(img, 1, rgb_mask, 0.5, 0)
      cv2.rectangle(img, boxes[i][0], boxes[i][1],color=(0, 255, 0), thickness=rect_th)
      cv2.putText(img,pred_cls[i], boxes[i][0], cv2.FONT_HERSHEY_SIMPLEX, text_size, (0,255,0),thickness=text_th)
    plt.figure(figsize=(20,30))
    plt.imshow(img)
    plt.xticks([])
    plt.yticks([])
    plt.show()

segment_instance('image1.png', confidence=0.4)

错误信息 #

Input In [31], in segment_instance(img_path, confidence, rect_th, text_size, text_th)
     20   rgb_mask = get_coloured_mask(masks[i])
     21   img = cv2.addWeighted(img, 1, rgb_mask, 0.5, 0)
---> 22   cv2.rectangle(img, boxes[i][0], boxes[i][1],color=(0, 255, 0), thickness=rect_th)
     23   cv2.putText(img,pred_cls[i], boxes[i][0], cv2.FONT_HERSHEY_SIMPLEX, text_size, (0,255,0),thickness=text_th)
     24 plt.figure(figsize=(20,30))

error: OpenCV(4.6.0) :-1: error: (-5:Bad argument) in function 'rectangle'

Overload resolution failed:

• Can't parse 'pt1'. Sequence item with index 0 has a wrong type
• Can't parse 'pt1'. Sequence item with index 0 has a wrong type
• argument for rectangle() given by name ('color') and position (3)
• argument for rectangle() given by name ('color') and position (3)

解决思路 #

• 修正坐标类型与格式：OpenCV的rectangle要求pt1和pt2必须是整数类型的元组，每个坐标元素都得是int。当前代码中pred_boxes生成的是numpy浮点类型的元组，需修改生成逻辑，逐个转换坐标为int：

  pred_boxes = [[(int(i[0]), int(i[1])), (int(i[2]), int(i[3]))] for i in list(pred[0]['boxes'].detach().cpu().numpy())]
  

• 统一参数传递方式：错误提示显示混合位置参数与关键字参数导致重载解析失败，可调整rectangle的调用方式：

  # 方式1：去掉color关键字，按位置传参
  cv2.rectangle(img, boxes[i][0], boxes[i][1], (0, 255, 0), rect_th)
  # 方式2：全部使用关键字参数（适配新版本OpenCV）
  cv2.rectangle(img=img, pt1=boxes[i][0], pt2=boxes[i][1], color=(0, 255, 0), thickness=rect_th)
  

• 额外校验点：

  • 确认boxes中的坐标值在图像宽高范围内，避免负数或超出边界的情况
  • 检查get_prediction中pred_t的取值逻辑，确保pred_boxes、masks、pred_cls三者长度一致，防止索引越界

内容的提问来源于stack exchange，提问作者dilara