1.Android自带的人脸识别Android自带的人脸识别只能识别出人脸在画面中的位置，中点，眼间距，角度等基本特性，提供给拍照性质的应用使用。从基本功能中不能得出明显的特征数据

2.底层库支持external/neven/*

3.接口frameworks/base/media/java/android/media/FaceDetector.java

4.Android源码参考packages/apps/Gallery/src/com/android/camera/*

5.关键代码分析

package com.android.mydetect;

import android.app.Activity;

import android.widget.TextView;

import android.os.Bundle;

import android.media.FaceDetector;//人脸识别接口

import android.widget.ImageView;

import android.graphics.BitmapFactory;

import android.graphics.Bitmap;

import android.graphics.PointF;

import android.graphics.Matrix;

import android.util.Log;

import android.graphics.Canvas;

import android.graphics.Paint;

public class MyDetectActivity extends Activity {

private ImageView mImageView;//图片显示控件

private Bitmap mBitmap;

private float mScale = 1F;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

mImageView = (ImageView) this.findViewById(R.id.image);

detect();//识别函数

}

private void handleFace(FaceDetector.Face f) {//在图片上对每张脸进行处理

PointF midPoint = new PointF();

int r = ((int) (f.eyesDistance() * mScale * 1.5));//取眼睛间距离

f.getMidPoint(midPoint);//取脸的中点

midPoint.x *= mScale;

midPoint.y *= mScale;

Canvas c = new Canvas(mBitmap);

Paint p = new Paint();

p.setAntiAlias(true);

p.setAlpha(0x80);

c.drawCircle(midPoint.x, midPoint.y, r, p)//用半透明标出人脸区域;

mImageView.setImageBitmap(mBitmap);//显示图片

}

private void detect() {

Matrix matrix = new Matrix();

FaceDetector.Face[] mFaces = new FaceDetector.Face[3];//定义最多识别三张脸

int mNumFaces = 0;

mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.baby);//取原始图

if (mBitmap == null) {

return;

}

if (mBitmap.getWidth() > 256) {

mScale = 256.0F / mBitmap.getWidth();

}

matrix.setScale(mScale, mScale);

Bitmap faceBitmap = Bitmap.createBitmap(mBitmap, 0, 0, mBitmap

.getWidth(), mBitmap.getHeight(), matrix, true);//生成缩放后的新图

mScale = 1.0F / mScale;

if (faceBitmap != null) {

FaceDetector detector = new FaceDetector(faceBitmap.getWidth(),

faceBitmap.getHeight(), mFaces.length);//创建识别器

mNumFaces = detector.findFaces(faceBitmap, mFaces);//识别

if (mNumFaces > 0) {

for (int i = 0; i < mNumFaces; i++) {

handleFace(mFaces[i]);//调用函数对人脸画面进行处理

}

}

}

}

}