detect.py

from ultralytics import YOLO
from ultralytics.utils.plotting import Annotator  # ultralytics.yolo.utils.plotting is deprecated

import cv2

# モデル読み込み（https://github.com/ultralytics/assets/releases/download/v0.0.0/yolov8n.pt）
model = YOLO("yolov8n.pt")

cap = cv2.VideoCapture(0)
cap.set(3, 640)
cap.set(4, 480)

while True:
    _, img = cap.read()
    
    # BGR to RGB conversion is performed under the hood
    # see: https://github.com/ultralytics/ultralytics/issues/2575
    results = model.predict(img)

    for r in results:
        
        annotator = Annotator(img)
        
        boxes = r.boxes
        for box in boxes:
            
            b = box.xyxy[0]  # get box coordinates in (left, top, right, bottom) format
            c = box.cls
            annotator.box_label(b, model.names[int(c)])
          
    img = annotator.result()  
    cv2.imshow('YOLO V8 Detection', img)     
    if cv2.waitKey(1) & 0xFF == ord(' '):
        break

cap.release()
cv2.destroyAllWindows()