opencv-TypeError：无法读取未定义的属性“长度”

Question

I recently installed opencv and executed npm install .

After doing that, I was given some sample code to see if it works, but it does not work, and I don't know why. Maybe I installed it incorrectly, I am a newbie to this. Here is the code:

cv.readImage("./examples/files/mona.png", function(err, im){
  im.detectObject(cv.FACE_CASCADE, {}, function(err, faces){
    for (var i=0;i<faces.length; i++){
      var x = faces[i]
      im.ellipse(x.x + x.width/2, x.y + x.height/2, x.width/2, x.height/2);
    }
    im.save('./out.jpg');
  });
})

Answer 1

You should install it by "npm install opencv --save" But since there is no dependency issue so you installed it right. Try doing console.log(faces) because it is giving null as result in faces that's why length is undefined. Also make sure the image at that path you are giving "./examples/files/mona.png" do exist.