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环境：
Mac M1 (MacOS Sonoma 14.3.1)
Python 3.11+PyTorch 2.1.2
一、准备工作
使用YOLO一般都会接触ultralytics这个框架，今天来试试用该框架进行YOLO V9模型的推理。
YOLOv9目前提供了四种模型下载：yolov9-c.pt、yolov9-e.pt、gelan-c.pt、gelan-e.pt
wget -P /Users/zhujiahui/Local/model/yolov9 -q https://github.com/WongKinYiu/yolov9/releases/download/v0.1/yolov9-c.pt
wget -P /Users/zhujiahui/Local/model/yolov9 -q https://github.com/WongKinYiu/yolov9/releases/download/v0.1/yolov9-e.pt
wget -P /Users/zhujiahui/Local/model/yolov9 -q https://github.com/WongKinYiu/yolov9/releases/download/v0.1/gelan-c.pt
wget -P /Users/zhujiahui/Local/model/yolov9 -q https://github.com/WongKinYiu/yolov9/releases/download/v0.1/gelan-e.pt将下载好的模型放到指定的位置（实际发现这一步不用做，白费了）。
下载示例图片（也可手动下载放置），放到指定位置下：
wget -P /Users/zhujiahui/Local/dataset -q https://media.roboflow.com/notebooks/examples/dog.jpeg安装Python依赖
pip install opencv-python
pip install ultralytics二、推理
编写以下代码：
from ultralytics import YOLOdef yolov9_inference():yolo_model = YOLO("/Users/zhujiahui/Local/model/yolov9/yolov9-e.pt")yolo_model.info()if __name__ == '__main__':yolov9_inference()直接运行，发现报错：
TypeError: ERROR ❌️ /Users/zhujiahui/Local/model/yolov9/yolov9-e.pt appears to be an Ultralytics YOLOv5 model originally trained with https://github.com/ultralytics/yolov5.
This model is NOT forwards compatible with YOLOv8 at https://github.com/ultralytics/ultralytics.
Recommend fixes are to train a new model using the latest 'ultralytics' package or to run a command with an official YOLOv8 model, i.e. 'yolo predict model=yolov8n.pt'
意思是说从https://github.com/WongKinYiu/yolov9下载的模型yolov9-e.pt与本训练推理框架（ultralytics）不match，必须使用经过ultralytics训练的模型。
于是改动如下，选用ultralytics提供的YOLO V9模型：
from ultralytics import YOLOdef yolov9_inference():yolo_model = YOLO("yolov9e.pt")yolo_model.info()if __name__ == '__main__':yolov9_inference()首次运行会下载模型到当前代码所在的文件夹下
对示例图片进行检测：
from ultralytics import YOLOdef yolov9_inference():yolo_model = YOLO("yolov9e.pt")yolo_model.info()results = yolo_model.predict(source='/Users/zhujiahui/Local/dataset/dog.jpeg', save=True, save_txt=True)print(results)if __name__ == '__main__':yolov9_inference()结果如下：
具体检测后的结果图片在runs/detect/predict/dog.jpeg下，效果：
 |  |
| 原图 | 检测结果 |
输入的图片也可以通过OpenCV读入：
def yolov9_inference2():yolo_model = YOLO("yolov9e.pt")yolo_model.info()input_image = cv2.imread("/Users/zhujiahui/Local/dataset/dog.jpeg")results = yolo_model.predict(source=input_image, save=True, save_txt=True)print(results)