Question

Currently I’m working on an app for Android phones. We want to detect features of a face. The programm should be able to detect the positions of the eyes, the nose, the mouth and the edge of the face.

Accuracy should be fine but doesn’t need to be perfect. It’s okay to loose some accuracy to speed things up. All the faces will be frontal and we will know the approximate positions of the features before. We don’t need live detection. The features should be extracted from saved images. The detection time should be only as long as it doesn’t disturbe the user experience. So maybe even 2 or 3 seconds are okay.

With this assumptions it shouldn’t be too hard to find a library which enables us to achieve this. But my question is, what is the best approach? What’s your suggestion? It’s the first time for me developing for Android and I don’t want to run in the wrong direction. Is it a good idea to us a library or is it better (faster/higher accuracy) to implement some existing algorithm on my own?

I googled a lot and I found many interesting things. There is also a face detection in the Android API. But the returned face class (http://developer.android.com/reference/android/media/FaceDetector.Face.html) only contains the position of the eyes. This is to less for our applicaton. Then there is also OpenCV for Android or JavaCV. What do you think is a good idea to work with? For what library there are good documentations, tutorials?

Answer 1

OpenCV has a tutorial for this purpose, unfortunately is C++ only so you would have to convert it to Android.

You can also try FaceDetection API in Android, this is a simple example if you are detecting images from a drawable or sdcard images. Or the more recent Camera.Face API which works with the camera image.

If you want image from your camera at dynamic time than first read How to take picture from camera., but I would recommend you to check the official OpenCV Android samples and use them.

Updated:

Mad Hatter Example use the approach of Camera with SurfaceView. Its promisingly fast. Have a look at Mad Hatter.

The relevant code, in case the link goes down, is this:

public class FaceDetectionListener implements Camera.FaceDetectionListener {
    @Override
    public final void onFaceDetection(Face[] faces, Camera camera) {
        if (faces.length > 0) {
            for (Face face : faces) {
                if (face != null) {
                    // do something
                }
            }
        }
    }
}