python - 使用 Python 选择第一面 OpenCV detectMultiScale

Question

我正在测试 OpenCV 来检测人脸，我想知道如何才能有效地只检测到第一张人脸？

下面的代码适用于多个，但如果我在 faces[0] 上执行 for 循环，应用程序会提示:

for (x,y,w,h) in faces[0]:
TypeError: 'numpy.int32' object is not iterable


if len(faces) == 0:
        print('the list is empty', datetime.now().strftime("%Y-%m-%d %H:%M:%S"))
    else:
        print('the list is NOT empty', 'Detected',len(faces),'Face(s)')
        print(faces)

        for (x,y,w,h) in faces:
            cv.rectangle(img,(x,y),(x+w,y+h),(0,0,255),2)
            roi_color = img[y:y+h, x:x+w]  

    cv.imshow('Facial Recognition', img)

Answer 1

faces[0] 只是一张脸，所以你不能循环它。

if len(faces) == 0:
    print('the list is empty', datetime.now().strftime("%Y-%m-%d %H:%M:%S"))
else:
    print('the list is NOT empty', 'Detected',len(faces),'Face(s)')
    print(faces)

    face = faces[0]
    (x,y,w,h) = face 
    cv.rectangle(img,(x,y),(x+w,y+h),(0,0,255),2)
    roi_color = img[y:y+h, x:x+w]  

cv.imshow('Facial Recognition', img)