Introducing Face Detection in the Google Vision APIs

The Google Vision APIs provide two main areas of functionality.

First is Face Tracking -- not to be confused with Facial Recognition -- which gives your apps the ability to detect faces, and landmarks on faces. This is useful for, for example -- writing a camera app that only takes a picture when everyone is smiling, and nobody is blinking, or for fun apps where you can superimpose hats or moustaches on people in the camera preview window. 

Second is recognizing visual codes such as bar codes or QR codes, and making it easy for developers to build apps with them.

---

~ My step-by-step posts of Face Detection with Google Play services, Mobile Vision API

Google Play services Face Detection, detect Smiling

With Face Detection of Google Play services, Mobile Vision API, you can detect various facial states; such as Smiling, Left Eye Open or Right Eye Open.

This example show how to detect Smiling face with getIsSmilingProbability() method of com.google.android.gms.vision.face.Face. You can also use getIsLeftEyeOpenProbability() and getIsRightEyeOpenProbability() methods to test if the face's left or right eye is open.


Modify from last post of "Google Play services Face Detection, get Landmarks (eyes, nose, etc.)". Call setClassificationType(FaceDetector.ALL_CLASSIFICATIONS) method when build FaceDetector with FaceDetector.Builder. Then call getIsSmilingProbability() method of the detected faces to check if it is similing.

package com.example.androidfacedetection;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.SparseArray;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import com.google.android.gms.vision.Frame;
import com.google.android.gms.vision.face.Face;
import com.google.android.gms.vision.face.FaceDetector;
import com.google.android.gms.vision.face.Landmark;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private static final int RQS_LOADIMAGE = 1;
    private Button btnLoad, btnDetFace;
    private ImageView imgView;
    private Bitmap myBitmap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnLoad = (Button)findViewById(R.id.btnLoad);
        btnDetFace = (Button)findViewById(R.id.btnDetectFace);
        imgView = (ImageView)findViewById(R.id.imgview);

        btnLoad.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setType("image/*");
                intent.setAction(Intent.ACTION_GET_CONTENT);
                intent.addCategory(Intent.CATEGORY_OPENABLE);
                startActivityForResult(intent, RQS_LOADIMAGE);
            }
        });

        btnDetFace.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                if(myBitmap == null){
                    Toast.makeText(MainActivity.this,
                            "myBitmap == null",
                            Toast.LENGTH_LONG).show();
                }else{
                    detectFace();

                }
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == RQS_LOADIMAGE
                && resultCode == RESULT_OK){

            if(myBitmap != null){
                myBitmap.recycle();
            }

            try {
                InputStream inputStream =
                        getContentResolver().openInputStream(data.getData());
                myBitmap = BitmapFactory.decodeStream(inputStream);
                inputStream.close();
                imgView.setImageBitmap(myBitmap);

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        super.onActivityResult(requestCode, resultCode, data);
    }

    /*
    reference:
    https://search-codelabs.appspot.com/codelabs/face-detection
     */
    private void detectFace(){

        //Create a Paint object for drawing with
        Paint myRectPaint = new Paint();
        myRectPaint.setStrokeWidth(5);
        myRectPaint.setColor(Color.GREEN);
        myRectPaint.setStyle(Paint.Style.STROKE);

        Paint landmarksPaint = new Paint();
        landmarksPaint.setStrokeWidth(10);
        landmarksPaint.setColor(Color.RED);
        landmarksPaint.setStyle(Paint.Style.STROKE);

        Paint smilingPaint = new Paint();
        smilingPaint.setStrokeWidth(4);
        smilingPaint.setColor(Color.YELLOW);
        smilingPaint.setStyle(Paint.Style.STROKE);

        boolean somebodySmiling = false;

        //Create a Canvas object for drawing on
        Bitmap tempBitmap = Bitmap.createBitmap(myBitmap.getWidth(), myBitmap.getHeight(), Bitmap.Config.RGB_565);
        Canvas tempCanvas = new Canvas(tempBitmap);
        tempCanvas.drawBitmap(myBitmap, 0, 0, null);

        //Detect the Faces

        //!!!
        //Cannot resolve method setTrackingEnabled(boolean)
        //FaceDetector faceDetector = new FaceDetector.Builder(getApplicationContext()).build();
        //faceDetector.setTrackingEnabled(false);

        FaceDetector faceDetector =
                new FaceDetector.Builder(getApplicationContext())
                .setTrackingEnabled(false)
                        .setLandmarkType(FaceDetector.ALL_LANDMARKS)
                        .setClassificationType(FaceDetector.ALL_CLASSIFICATIONS)
                        .build();

        Frame frame = new Frame.Builder().setBitmap(myBitmap).build();
        SparseArray<Face> faces = faceDetector.detect(frame);

        //Draw Rectangles on the Faces
        for(int i=0; i<faces.size(); i++) {
            Face thisFace = faces.valueAt(i);
            float x1 = thisFace.getPosition().x;
            float y1 = thisFace.getPosition().y;
            float x2 = x1 + thisFace.getWidth();
            float y2 = y1 + thisFace.getHeight();
            tempCanvas.drawRoundRect(new RectF(x1, y1, x2, y2), 2, 2, myRectPaint);

            //get Landmarks for the first face
            List<Landmark> landmarks = thisFace.getLandmarks();
            for(int l=0; l<landmarks.size(); l++){
                PointF pos = landmarks.get(l).getPosition();
                tempCanvas.drawPoint(pos.x, pos.y, landmarksPaint);
            }

            //check if this face is Smiling
            final float smilingAcceptProbability = 0.5f;
            float smilingProbability = thisFace.getIsSmilingProbability();
            if(smilingProbability > smilingAcceptProbability){
                tempCanvas.drawOval(new RectF(x1, y1, x2, y2), smilingPaint);
                somebodySmiling = true;
            }
        }

        imgView.setImageDrawable(new BitmapDrawable(getResources(), tempBitmap));

        if(somebodySmiling){
            Toast.makeText(MainActivity.this,
                    "Done - somebody is Smiling",
                    Toast.LENGTH_LONG).show();
        }else{
            Toast.makeText(MainActivity.this,
                    "Done - nobody is Smiling",
                    Toast.LENGTH_LONG).show();
        }
        
    }
}

Other files, AndroidManifest.xml and layout/activity_main.xml, refer to the post "Face Detection with Google Play services, Mobile Vision API".

Google Play services Face Detection, get Landmarks (eyes, nose, etc.)

getLandmarks() method of com.google.android.gms.vision.face.Face return a list of Landmarks (eyes, nose, etc.) found on the face. A landmark detector must be specified via setLandmarkType(int) to detect landmarks. The landmark detector may not find all possible landmarks on any given face.

This example modify from the post "Face Detection with Google Play services, Mobile Vision API", with fix of "FaceDetector error: Cannot resolve method setTrackingEnabled(boolean)", add the feature to detect landmarks on detected faces.


Sets detect all landmarks, by calling setLandmarkType(FaceDetector.ALL_LANDMARKS) when build FaceDetector with FaceDetector.Builder.

Then call getLandmarks() for each detected faces.

com.example.androidfacedetection.MainActivity.java

package com.example.androidfacedetection;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.SparseArray;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import com.google.android.gms.vision.Frame;
import com.google.android.gms.vision.face.Face;
import com.google.android.gms.vision.face.FaceDetector;
import com.google.android.gms.vision.face.Landmark;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private static final int RQS_LOADIMAGE = 1;
    private Button btnLoad, btnDetFace;
    private ImageView imgView;
    private Bitmap myBitmap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnLoad = (Button)findViewById(R.id.btnLoad);
        btnDetFace = (Button)findViewById(R.id.btnDetectFace);
        imgView = (ImageView)findViewById(R.id.imgview);

        btnLoad.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setType("image/*");
                intent.setAction(Intent.ACTION_GET_CONTENT);
                intent.addCategory(Intent.CATEGORY_OPENABLE);
                startActivityForResult(intent, RQS_LOADIMAGE);
            }
        });

        btnDetFace.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                if(myBitmap == null){
                    Toast.makeText(MainActivity.this,
                            "myBitmap == null",
                            Toast.LENGTH_LONG).show();
                }else{
                    detectFace();
                    Toast.makeText(MainActivity.this,
                            "Done",
                            Toast.LENGTH_LONG).show();
                }
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == RQS_LOADIMAGE
                && resultCode == RESULT_OK){

            if(myBitmap != null){
                myBitmap.recycle();
            }

            try {
                InputStream inputStream =
                        getContentResolver().openInputStream(data.getData());
                myBitmap = BitmapFactory.decodeStream(inputStream);
                inputStream.close();
                imgView.setImageBitmap(myBitmap);

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        super.onActivityResult(requestCode, resultCode, data);
    }

    /*
    reference:
    https://search-codelabs.appspot.com/codelabs/face-detection
     */
    private void detectFace(){

        //Create a Paint object for drawing with
        Paint myRectPaint = new Paint();
        myRectPaint.setStrokeWidth(5);
        myRectPaint.setColor(Color.GREEN);
        myRectPaint.setStyle(Paint.Style.STROKE);

        Paint landmarksPaint = new Paint();
        landmarksPaint.setStrokeWidth(10);
        landmarksPaint.setColor(Color.RED);
        landmarksPaint.setStyle(Paint.Style.STROKE);

        //Create a Canvas object for drawing on
        Bitmap tempBitmap = Bitmap.createBitmap(myBitmap.getWidth(), myBitmap.getHeight(), Bitmap.Config.RGB_565);
        Canvas tempCanvas = new Canvas(tempBitmap);
        tempCanvas.drawBitmap(myBitmap, 0, 0, null);

        //Detect the Faces


        //!!!
        //Cannot resolve method setTrackingEnabled(boolean)
        //FaceDetector faceDetector = new FaceDetector.Builder(getApplicationContext()).build();
        //faceDetector.setTrackingEnabled(false);

        FaceDetector faceDetector =
                new FaceDetector.Builder(getApplicationContext())
                .setTrackingEnabled(false)
                        .setLandmarkType(FaceDetector.ALL_LANDMARKS)
                        .build();

        Frame frame = new Frame.Builder().setBitmap(myBitmap).build();
        SparseArray<Face> faces = faceDetector.detect(frame);

        //Draw Rectangles on the Faces
        for(int i=0; i<faces.size(); i++) {
            Face thisFace = faces.valueAt(i);
            float x1 = thisFace.getPosition().x;
            float y1 = thisFace.getPosition().y;
            float x2 = x1 + thisFace.getWidth();
            float y2 = y1 + thisFace.getHeight();
            tempCanvas.drawRoundRect(new RectF(x1, y1, x2, y2), 2, 2, myRectPaint);

            //get Landmarks for the first face
            List<Landmark> landmarks = thisFace.getLandmarks();
            for(int l=0; l<landmarks.size(); l++){
                PointF pos = landmarks.get(l).getPosition();
                tempCanvas.drawPoint(pos.x, pos.y, landmarksPaint);
            }
        }

        imgView.setImageDrawable(new BitmapDrawable(getResources(),tempBitmap));

    }
}

Other files, AndroidManifest.xml and layout/activity_main.xml, refer to the post "Face Detection with Google Play services, Mobile Vision API".

Next:
- Google Play services Face Detection, detect Smiling

FaceDetector error: Cannot resolve method setTrackingEnabled(boolean)

As mentioned in last post "Face Detection with Google Play services, Mobile Vision API (with demo APK)", calling setTrackingEnabled(false) method of FaceDetector object return error of "Cannot resolve method setTrackingEnabled(boolean)".

After checking reference of com.google.android.gms.vision.face.FaceDetector, setTrackingEnabled(boolean) is not a method of FaceDetector class. It's a method of com.google.android.gms.vision.face.FaceDetector.Builder class.

---

public FaceDetector.Builder setTrackingEnabled (boolean trackingEnabled)
Enables or disables face tracking, which will maintain a consistent ID for each face when processing consecutive frames. Default: true

If your code uses a MultiProcessor or FocusingProcessor instance, tracking must be enabled. Having tracking enabled is also recommended for handling live video.

Tracking should be disabled for handling a series of non-consecutive still images.

---

To fix the error, modify the code

        FaceDetector faceDetector = new FaceDetector.Builder(getApplicationContext()).build();
        faceDetector.setTrackingEnabled(false);

to:

        FaceDetector faceDetector =
                new FaceDetector.Builder(getApplicationContext())
                .setTrackingEnabled(false)
                .build();

Face Detection with Google Play services, Mobile Vision API (with demo APK)

With the release of Google Play services 7.8, new Mobile Vision APIs was added, to include a new Face API that finds human faces in images and video. ~ source: Android Developers Blog - Face Detection in Google Play services.

Follow the code lab "Face Detection with the Mobile Vision API", you can create an App to process an image that is already present in your app, to detects faces.

In this exercise, I modify the code lab to add the feature to load photos using Intent of ACTION_GET_CONTENT, such that you can test it with your own photos. APK is available on the bottom of this post.

- Make sure you have Google Play Services 7.8 or higher installed on your testing devices (Check your installed Google Play Services version).

- Create your app of "Blank Activity", with Min Sdk Version of API 17 (Android 4.2.2) or higher.

- Add dependency for Google Play services in Android Studio Project, make sure you have Google Play Services version 26 or higher installed.

- Edit your AndroidManifest.xml to add the statement of <meta-data...>:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.androidfacedetection" >
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <meta-data
            android:name="com.google.android.gms.vision.DEPENDENCIES"
            android:value="face" />
    </application>

</manifest>

layout/activity_main.xml

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:textSize="18dp"
        android:text="Face Detection with the Mobile Vision API" />

    <Button
        android:id="@+id/btnLoad"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Load Photo"/>

    <Button
        android:id="@+id/btnDetectFace"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Detect Face" />

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/imgview"/>

</LinearLayout>

com.example.androidfacedetection.MainActivity.java

package com.example.androidfacedetection;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.SparseArray;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import com.google.android.gms.vision.Frame;
import com.google.android.gms.vision.face.Face;
import com.google.android.gms.vision.face.FaceDetector;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

public class MainActivity extends AppCompatActivity {

    private static final int RQS_LOADIMAGE = 1;
    private Button btnLoad, btnDetFace;
    private ImageView imgView;
    private Bitmap myBitmap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnLoad = (Button)findViewById(R.id.btnLoad);
        btnDetFace = (Button)findViewById(R.id.btnDetectFace);
        imgView = (ImageView)findViewById(R.id.imgview);

        btnLoad.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setType("image/*");
                intent.setAction(Intent.ACTION_GET_CONTENT);
                intent.addCategory(Intent.CATEGORY_OPENABLE);
                startActivityForResult(intent, RQS_LOADIMAGE);
            }
        });

        btnDetFace.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                if(myBitmap == null){
                    Toast.makeText(MainActivity.this,
                            "myBitmap == null",
                            Toast.LENGTH_LONG).show();
                }else{
                    detectFace();
                    Toast.makeText(MainActivity.this,
                            "Done",
                            Toast.LENGTH_LONG).show();
                }
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == RQS_LOADIMAGE
                && resultCode == RESULT_OK){

            if(myBitmap != null){
                myBitmap.recycle();
            }

            try {
                InputStream inputStream =
                        getContentResolver().openInputStream(data.getData());
                myBitmap = BitmapFactory.decodeStream(inputStream);
                inputStream.close();
                imgView.setImageBitmap(myBitmap);

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        super.onActivityResult(requestCode, resultCode, data);
    }

    /*
    reference:
    https://search-codelabs.appspot.com/codelabs/face-detection
     */
    private void detectFace(){

        //Create a Paint object for drawing with
        Paint myRectPaint = new Paint();
        myRectPaint.setStrokeWidth(5);
        myRectPaint.setColor(Color.RED);
        myRectPaint.setStyle(Paint.Style.STROKE);

        //Create a Canvas object for drawing on
        Bitmap tempBitmap = Bitmap.createBitmap(myBitmap.getWidth(), myBitmap.getHeight(), Bitmap.Config.RGB_565);
        Canvas tempCanvas = new Canvas(tempBitmap);
        tempCanvas.drawBitmap(myBitmap, 0, 0, null);

        //Detect the Faces
        FaceDetector faceDetector = new FaceDetector.Builder(getApplicationContext()).build();

        //!!!
        //Cannot resolve method setTrackingEnabled(boolean)
        //skip for now
        //faceDetector.setTrackingEnabled(false);

        Frame frame = new Frame.Builder().setBitmap(myBitmap).build();
        SparseArray<Face> faces = faceDetector.detect(frame);

        //Draw Rectangles on the Faces
        for(int i=0; i<faces.size(); i++) {
            Face thisFace = faces.valueAt(i);
            float x1 = thisFace.getPosition().x;
            float y1 = thisFace.getPosition().y;
            float x2 = x1 + thisFace.getWidth();
            float y2 = y1 + thisFace.getHeight();
            tempCanvas.drawRoundRect(new RectF(x1, y1, x2, y2), 2, 2, myRectPaint);
        }
        imgView.setImageDrawable(new BitmapDrawable(getResources(),tempBitmap));

    }
}

In my trial:
- The calling of faceDetector.setTrackingEnabled(false) report error of "Cannot resolve method setTrackingEnabled(boolean)"! So I skip it in this example.
(fixed in next post: "FaceDetector error: Cannot resolve method setTrackingEnabled(boolean)")

- It work on RedMi 2, running Android 4.4.4, with Google Play services version 7.8.99 installed.
- But cannot detect face on Nexus 7 2012 (WITHOUT front camera) running Android 5.1.1, with the same Google Play services version 7.8.99 installed! with warning of "FaceDetectorHandle﹕ Native face detector not yet available.  Reverting to no-op detection".

Test on RedMi 2, running Android 4.4.4, with Google Play services version 7.8.99 installed.


Download the files (Android Studio Format).

You can also Download the APK here, for test without coding.

---

Next:
- FaceDetector error: Cannot resolve method setTrackingEnabled(boolean)
- Google Play services Face Detection, get Landmarks (eyes, nose, etc.)
- Detect Smiling
- Introducing Face Detection in the Google Vision APIs, from 100 Days of Google Dev

Android 4 Face Detection: Display detected face area

Further works on last exercise "Face detection for Camera". Once face detected, the call-back method onFaceDetection() of FaceDetectionListener will be called with parameter of Face[], a list of face objects. The face object, Face, contain bounds of the face (rect).

A custom View, DrawingView, is added to draw rectangle to show the detected face area, over the Preview SurfaceView.

For rect, bounds of the face: (-1000, -1000) represents the top-left of the camera field of view, and (1000, 1000) represents the bottom-right of the field of view ~ Refer http://developer.android.com/reference/android/hardware/Camera.Face.html#rect.

So we have to convert from (-1000, -1000)~(1000, 1000) to (0, 0)~(width, height of the View) in onDraw() of DrawingView.

Modify the main code in AndroidCamera.java

package com.exercise.AndroidCamera;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;

import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.Face;
import android.hardware.Camera.FaceDetectionListener;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore.Images.Media;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

public class AndroidCamera extends Activity implements SurfaceHolder.Callback{

 Camera camera;
 SurfaceView surfaceView;
 SurfaceHolder surfaceHolder;
 boolean previewing = false;
 LayoutInflater controlInflater = null;
 
 Button buttonTakePicture;
 TextView prompt;
 
 DrawingView drawingView;
 Face[] detectedFaces;
 
 final int RESULT_SAVEIMAGE = 0;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
        
        getWindow().setFormat(PixelFormat.UNKNOWN);
        surfaceView = (SurfaceView)findViewById(R.id.camerapreview);
        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        
        drawingView = new DrawingView(this);
        LayoutParams layoutParamsDrawing 
         = new LayoutParams(LayoutParams.FILL_PARENT, 
           LayoutParams.FILL_PARENT);
        this.addContentView(drawingView, layoutParamsDrawing);
        
        controlInflater = LayoutInflater.from(getBaseContext());
        View viewControl = controlInflater.inflate(R.layout.control, null);
        LayoutParams layoutParamsControl 
         = new LayoutParams(LayoutParams.FILL_PARENT, 
           LayoutParams.FILL_PARENT);
        this.addContentView(viewControl, layoutParamsControl);
        
        buttonTakePicture = (Button)findViewById(R.id.takepicture);
        buttonTakePicture.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    // TODO Auto-generated method stub
    camera.takePicture(myShutterCallback, 
      myPictureCallback_RAW, myPictureCallback_JPG);
   }});
        
        LinearLayout layoutBackground = (LinearLayout)findViewById(R.id.background);
        layoutBackground.setOnClickListener(new LinearLayout.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    // TODO Auto-generated method stub

    buttonTakePicture.setEnabled(false);
    camera.autoFocus(myAutoFocusCallback);
   }});
        
        prompt = (TextView)findViewById(R.id.prompt);
    }
    
    FaceDetectionListener faceDetectionListener
    = new FaceDetectionListener(){

  @Override
  public void onFaceDetection(Face[] faces, Camera camera) {
   
   if (faces.length == 0){
    prompt.setText(" No Face Detected! ");
    drawingView.setHaveFace(false);
   }else{
    prompt.setText(String.valueOf(faces.length) + " Face Detected :) ");
    drawingView.setHaveFace(true);
    detectedFaces = faces;
   }
   
   drawingView.invalidate();
   
  }};
    
    AutoFocusCallback myAutoFocusCallback = new AutoFocusCallback(){

  @Override
  public void onAutoFocus(boolean arg0, Camera arg1) {
   // TODO Auto-generated method stub
   buttonTakePicture.setEnabled(true);
  }};
    
    ShutterCallback myShutterCallback = new ShutterCallback(){

  @Override
  public void onShutter() {
   // TODO Auto-generated method stub
   
  }};
  
 PictureCallback myPictureCallback_RAW = new PictureCallback(){

  @Override
  public void onPictureTaken(byte[] arg0, Camera arg1) {
   // TODO Auto-generated method stub
   
  }};
  
 PictureCallback myPictureCallback_JPG = new PictureCallback(){

  @Override
  public void onPictureTaken(byte[] arg0, Camera arg1) {
   // TODO Auto-generated method stub
   /*Bitmap bitmapPicture 
    = BitmapFactory.decodeByteArray(arg0, 0, arg0.length); */
   
   Uri uriTarget = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, new ContentValues());

   OutputStream imageFileOS;
   try {
    imageFileOS = getContentResolver().openOutputStream(uriTarget);
    imageFileOS.write(arg0);
    imageFileOS.flush();
    imageFileOS.close();
    
    prompt.setText("Image saved: " + uriTarget.toString());
    
   } catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   camera.startPreview();
   camera.startFaceDetection();
  }};

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width,
   int height) {
  // TODO Auto-generated method stub
  if(previewing){
   camera.stopFaceDetection();
   camera.stopPreview();
   previewing = false;
  }
  
  if (camera != null){
   try {
    camera.setPreviewDisplay(surfaceHolder);
    camera.startPreview();

    prompt.setText(String.valueOf(
      "Max Face: " + camera.getParameters().getMaxNumDetectedFaces()));
    camera.startFaceDetection();
    previewing = true;
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
 }

 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  // TODO Auto-generated method stub
  camera = Camera.open();
  camera.setFaceDetectionListener(faceDetectionListener);
 }

 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  // TODO Auto-generated method stub
  camera.stopFaceDetection();
  camera.stopPreview();
  camera.release();
  camera = null;
  previewing = false;
 }
 
 private class DrawingView extends View{
  
  boolean haveFace;
  Paint drawingPaint;

  public DrawingView(Context context) {
   super(context);
   haveFace = false;
   drawingPaint = new Paint();
   drawingPaint.setColor(Color.GREEN);
   drawingPaint.setStyle(Paint.Style.STROKE); 
   drawingPaint.setStrokeWidth(2);
  }
  
  public void setHaveFace(boolean h){
   haveFace = h;
  }

  @Override
  protected void onDraw(Canvas canvas) {
   // TODO Auto-generated method stub
   if(haveFace){

    // Camera driver coordinates range from (-1000, -1000) to (1000, 1000).
     // UI coordinates range from (0, 0) to (width, height).
     
     int vWidth = getWidth();
     int vHeight = getHeight();
    
    for(int i=0; i<detectedFaces.length; i++){
     
     int l = detectedFaces[i].rect.left;
     int t = detectedFaces[i].rect.top;
     int r = detectedFaces[i].rect.right;
     int b = detectedFaces[i].rect.bottom;
     int left = (l+1000) * vWidth/2000;
     int top  = (t+1000) * vHeight/2000;
     int right = (r+1000) * vWidth/2000;
     int bottom = (b+1000) * vHeight/2000;
     canvas.drawRect(
       left, top, right, bottom,  
       drawingPaint);
    }
   }else{
    canvas.drawColor(Color.TRANSPARENT);
   }
  }
  
 }
}

Download the files.

Next: - Android 4 Face Detection: setFocusAreas() using face detected faces

Face detection for Camera

Long long time ago(2010-05-19), I have a post "Android FaceDetector" about how to use android.media.FaceDetector to identify faces in a Bitmap.

Start from Android 4, API Level 14, the android.hardware.Camera class provide the feature of Face Detection. You can build apps to detect face on camera at live.



The method startFaceDetection() starts the face detection. This should be called after preview is started. The camera will notify Camera.FaceDetectionListener of the detected faces in the preview frame. The detected faces may be the same as the previous ones. Applications should call stopFaceDetection() to stop the face detection. This method is supported if getMaxNumDetectedFaces() returns a number larger than 0. If the face detection has started, apps should not call this again.

When the face detection is running, setWhiteBalance(String), setFocusAreas(List), and setMeteringAreas(List) have no effect. The camera uses the detected faces to do auto-white balance, auto exposure, and autofocus.

If the apps call autoFocus(AutoFocusCallback), the camera will stop sending face callbacks. The last face callback indicates the areas used to do autofocus. After focus completes, face detection will resume sending face callbacks. If the apps call cancelAutoFocus(), the face callbacks will also resume.

After calling takePicture(Camera.ShutterCallback, Camera.PictureCallback, Camera.PictureCallback) or stopPreview(), and then resuming preview with startPreview(), the apps should call this method again to resume face detection.

It's modify from the exercise "Start Camera auto-focusing, autoFocus()" to add function of face detection.

Modify main.xml to add a SurfaceView for camera preview, and a TextView to display the number of face detected.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >

   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@string/hello" />
   <TextView
       android:id="@+id/prompt"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"/>
   <SurfaceView
       android:id="@+id/camerapreview" 
       android:layout_width="fill_parent"
       android:layout_height="wrap_content" />

</LinearLayout>

Create /res/layout/control.xml, it's a view overlap with the preview SurfaceView, to provide a button to take picture.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:id="@+id/background"
   android:orientation="vertical"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:gravity="bottom"
   >
<Button
 android:id="@+id/takepicture" 
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text=" * Take Picture "
 android:layout_gravity="right"
 android:layout_margin="10px"
 />
</LinearLayout>

Main code, call camera.startFaceDetection() after camera.startPreview(), and call camera.stopFaceDetection() before camera.stopPreview(), also define our FaceDetectionListener to display the result of number of face detected.

package com.exercise.AndroidCamera;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;

import android.app.Activity;
import android.content.ContentValues;
import android.content.pm.ActivityInfo;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.Face;
import android.hardware.Camera.FaceDetectionListener;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore.Images.Media;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

public class AndroidCamera extends Activity implements SurfaceHolder.Callback{

 Camera camera;
 SurfaceView surfaceView;
 SurfaceHolder surfaceHolder;
 boolean previewing = false;
 LayoutInflater controlInflater = null;
 
 Button buttonTakePicture;
 TextView prompt;
 
 final int RESULT_SAVEIMAGE = 0;
 
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
      
       getWindow().setFormat(PixelFormat.UNKNOWN);
       surfaceView = (SurfaceView)findViewById(R.id.camerapreview);
       surfaceHolder = surfaceView.getHolder();
       surfaceHolder.addCallback(this);
       surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
      
       controlInflater = LayoutInflater.from(getBaseContext());
       View viewControl = controlInflater.inflate(R.layout.control, null);
       LayoutParams layoutParamsControl
        = new LayoutParams(LayoutParams.FILL_PARENT,
        LayoutParams.FILL_PARENT);
       this.addContentView(viewControl, layoutParamsControl);
      
       buttonTakePicture = (Button)findViewById(R.id.takepicture);
       buttonTakePicture.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    // TODO Auto-generated method stub
    camera.takePicture(myShutterCallback,
      myPictureCallback_RAW, myPictureCallback_JPG);
   }});
      
       LinearLayout layoutBackground = (LinearLayout)findViewById(R.id.background);
       layoutBackground.setOnClickListener(new LinearLayout.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    // TODO Auto-generated method stub

    buttonTakePicture.setEnabled(false);
    camera.autoFocus(myAutoFocusCallback);
   }});
      
       prompt = (TextView)findViewById(R.id.prompt);
   }
  
   FaceDetectionListener faceDetectionListener
   = new FaceDetectionListener(){

  @Override
  public void onFaceDetection(Face[] faces, Camera camera) {
   
   if (faces.length == 0){
    prompt.setText(" No Face Detected! ");
   }else{
    prompt.setText(String.valueOf(faces.length) + " Face Detected :) ");
   }
   
   
  }};
  
   AutoFocusCallback myAutoFocusCallback = new AutoFocusCallback(){

  @Override
  public void onAutoFocus(boolean arg0, Camera arg1) {
   // TODO Auto-generated method stub
   buttonTakePicture.setEnabled(true);
  }};
  
   ShutterCallback myShutterCallback = new ShutterCallback(){

  @Override
  public void onShutter() {
   // TODO Auto-generated method stub
   
  }};
  
 PictureCallback myPictureCallback_RAW = new PictureCallback(){

  @Override
  public void onPictureTaken(byte[] arg0, Camera arg1) {
   // TODO Auto-generated method stub
   
  }};
  
 PictureCallback myPictureCallback_JPG = new PictureCallback(){

  @Override
  public void onPictureTaken(byte[] arg0, Camera arg1) {
   // TODO Auto-generated method stub
   /*Bitmap bitmapPicture
    = BitmapFactory.decodeByteArray(arg0, 0, arg0.length); */
   
   Uri uriTarget = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, new ContentValues());

   OutputStream imageFileOS;
   try {
    imageFileOS = getContentResolver().openOutputStream(uriTarget);
    imageFileOS.write(arg0);
    imageFileOS.flush();
    imageFileOS.close();
    
    prompt.setText("Image saved: " + uriTarget.toString());
    
   } catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   
   camera.startPreview();
   camera.startFaceDetection();
  }};

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width,
   int height) {
  // TODO Auto-generated method stub
  if(previewing){
   camera.stopFaceDetection();
   camera.stopPreview();
   previewing = false;
  }
  
  if (camera != null){
   try {
    camera.setPreviewDisplay(surfaceHolder);
    camera.startPreview();

    prompt.setText(String.valueOf(
      "Max Face: " + camera.getParameters().getMaxNumDetectedFaces()));
    camera.startFaceDetection();
    previewing = true;
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
 }

 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  // TODO Auto-generated method stub
  camera = Camera.open();
  camera.setFaceDetectionListener(faceDetectionListener);
 }

 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  // TODO Auto-generated method stub
  camera.stopFaceDetection();
  camera.stopPreview();
  camera.release();
  camera = null;
  previewing = false;
 }
}

Modify AndroidManifest.xml, to add permission of "android.permission.CAMERA", and set android:minSdkVersion="14".

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.exercise.AndroidCamera"
   android:versionCode="1"
   android:versionName="1.0" >

   <uses-sdk android:minSdkVersion="14" />
   <uses-permission android:name="android.permission.CAMERA"/>

   <application
       android:icon="@drawable/ic_launcher"
       android:label="@string/app_name" >
       <activity
           android:name=".AndroidCamera"
           android:label="@string/app_name" >
           <intent-filter>
               <action android:name="android.intent.action.MAIN" />

               <category android:name="android.intent.category.LAUNCHER" />
           </intent-filter>
       </activity>
   </application>

</manifest>

Download the files.

Please note, it's a in-complete exercise. It simple display the number of face detected.

Next: - Android 4 Face Detection: Display detected face area

Android FaceDetector

Android provide a class android.media.FaceDetector to identify the faces of people in a Bitmap graphic object.



It's a simple exercise of face detection on Android. You have to place your own photo (in 320x480) into /res/drawable folder, or use the attached photos from the download link on the bottom of the text.

package com.exercise.AndroidFaceDetector;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.media.FaceDetector;
import android.media.FaceDetector.Face;
import android.os.Bundle;
import android.view.View;

public class AndroidFaceDetector extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.main);
        setContentView(new myView(this));
    }
    
    private class myView extends View{
     
     private int imageWidth, imageHeight;
     private int numberOfFace = 5;
     private FaceDetector myFaceDetect; 
     private FaceDetector.Face[] myFace;
     float myEyesDistance;
     int numberOfFaceDetected;
     
     Bitmap myBitmap;

  public myView(Context context) {
   super(context);
   // TODO Auto-generated constructor stub
   
   BitmapFactory.Options BitmapFactoryOptionsbfo = new BitmapFactory.Options();
   BitmapFactoryOptionsbfo.inPreferredConfig = Bitmap.Config.RGB_565; 
   myBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.face5, BitmapFactoryOptionsbfo);
   imageWidth = myBitmap.getWidth();
   imageHeight = myBitmap.getHeight();
   myFace = new FaceDetector.Face[numberOfFace];
   myFaceDetect = new FaceDetector(imageWidth, imageHeight, numberOfFace);
   numberOfFaceDetected = myFaceDetect.findFaces(myBitmap, myFace); 
   
  }

  @Override
  protected void onDraw(Canvas canvas) {
   // TODO Auto-generated method stub
   
            canvas.drawBitmap(myBitmap, 0, 0, null);
            
            Paint myPaint = new Paint();
            myPaint.setColor(Color.GREEN);
            myPaint.setStyle(Paint.Style.STROKE); 
            myPaint.setStrokeWidth(3);
            
            for(int i=0; i < numberOfFaceDetected; i++)
            {
             Face face = myFace[i];
             PointF myMidPoint = new PointF();
             face.getMidPoint(myMidPoint);
    myEyesDistance = face.eyesDistance();
             canvas.drawRect(
               (int)(myMidPoint.x - myEyesDistance),
               (int)(myMidPoint.y - myEyesDistance),
               (int)(myMidPoint.x + myEyesDistance),
               (int)(myMidPoint.y + myEyesDistance),
               myPaint);
            }
  }
    }
}

Download the files.

Related:
- Face detection for Camera

Updated:
- With the release of Google Play services 7.8, new Mobile Vision APIs was added, to include a new Face API that finds human faces in images and video. Read more: Face Detection with Google Play services, Mobile Vision API (with demo APK)