Android的人面識別功能(Face Detection)

Android的人面識別功能(Face Detection)

Android提供android.media.FaceDetector類, 它可以從一個位圖圖形(Bitmap)對象中辨認人面. 下面是一個使用FaceDetector的例子.



首先複製一個有人面的位圖文件到SD Card上, 名為face1.jpg. (參考"如何複製檔案到 SD Card")

創建FaceView.java

package com.AndroidFaceDetection;

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.util.AttributeSet;
import android.view.View;

public class FaceView extends View {

private final String faceImageUri = "/sdcard/face1.jpg";;

private Bitmap bitmapFace;
private int imageWidth, imageHeight;
private FaceDetector myFaceDetect;
private FaceDetector.Face[] faceDetected;
private final int numberOfFace = 5;
private int numberOfFaceDetected;

Paint paint;

public FaceView(Context context) {
 super(context);
 // TODO Auto-generated constructor stub
 initFaceView();
}

public FaceView(Context context, AttributeSet attrs) {
 super(context, attrs);
 // TODO Auto-generated constructor stub
 initFaceView();
}

public FaceView(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 // TODO Auto-generated constructor stub
 initFaceView();
}

private void initFaceView(){
 BitmapFactory.Options BitmapFactoryOptionsbfo = new BitmapFactory.Options();
 BitmapFactoryOptionsbfo.inPreferredConfig = Bitmap.Config.RGB_565;
 bitmapFace = BitmapFactory.decodeFile(faceImageUri);
 imageWidth = bitmapFace.getWidth();
 imageHeight = bitmapFace.getHeight();
 faceDetected = new FaceDetector.Face[numberOfFace];
 myFaceDetect = new FaceDetector(imageWidth, imageHeight, numberOfFace);
 numberOfFaceDetected = myFaceDetect.findFaces(bitmapFace, faceDetected); 

 paint = new Paint();
 paint.setColor(Color.WHITE);
 paint.setStyle(Paint.Style.STROKE);
 paint.setStrokeWidth(3);
}

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

 canvas.drawBitmap(bitmapFace, 0, 0, null);

 for(int i=0; i < numberOfFaceDetected; i++)
 {
  Face face = faceDetected[i];
  PointF faceMidPoint = new PointF();
  face.getMidPoint(faceMidPoint);
  canvas.drawPoint(faceMidPoint.x, faceMidPoint.y, paint);
  canvas.drawCircle(faceMidPoint.x, faceMidPoint.y, face.eyesDistance(), paint);
 }
}

}

修改main.xml使用FaceView類

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
<TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/hello"
  />
<com.AndroidFaceDetection.FaceView
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  />
</LinearLayout>

主程序AndroidFaceDetection.java無需修改.