title: iOS face detection failed with incompletely face
body: <p>I'm using Core Image for face detection like this:</p>
  
  <pre><code> CIImage* image = [CIImage imageWithCGImage:aImage.CGImage];
  
  //create Facedetector
  NSDictionary  *opts = [NSDictionary dictionaryWithObject:CIDetectorAccuracyHigh
                                                    forKey:CIDetectorAccuracy];
  CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace
                                            context:nil
                                            options:opts];
  
  //Pull out the features of the face and loop through them
  NSArray* features = [detector featuresInImage:image];
  </code></pre>
  
  <p>But I found that when I use a picture with completely face, it could detect the face correctly, but when I use a incompletely face, it failed , just as the following snapshot:
  <img src="https://i.stack.imgur.com/ETmoi.jpg" alt="enter image description here"> </p>
  
  <p>What's wrong with my code, does it that the CIDetector only works well with the completely face?</p>
  
  <p><strong>[update]</strong>
  <a href="https://www.dropbox.com/s/yk2vkqrky1f2tko/facetest.zip?dl=0" rel="nofollow noreferrer">here</a> is my code, I could only detect the left</p>