http://m.blog.csdn.net/blogercn/article/details/75004162
1.高端数码相机都具有背景虚化功能。背景虚化就是使景深变浅，使焦点聚集在主题上。一般的相机最好的虚拟方法便是用微距拍摄，如果主景与背景相距比较远，由于光学透镜对非焦点处景物的不能清晰成像的特点，可以免强实现类似虚化效果。如下。
2.相机拍摄背景虚化照片一般需要经过四个步骤：
（1）使变焦倍率（焦距）尽可能大；
（2）拍摄物与背景尽可能距离远；
（3）镜头与拍摄物尽可能距离近；
（4）光圈在满足拍摄需要的同时尽可能大，即F值小；
3.对于不支持背景虚化的相机，可以使用软件实现背景虚化，以满足不同客户的需求。
要使用软件技术精确的背景虚化，需要经过三个步骤：
一是选定区域，根据远区使用抠图技术实现前背景分离
二对背景根据需要使用高斯或者平均值等模糊方法处理
三把处理后的背景和前景合并
前景背景分离这个里使用OPENCV和grabCut技术实现，项目导入我自己编绎的opencv的AAR包，把OPENCV库放入LIBS文件夹，修改APP的build.gradle，添加LIBS：
repositories {
mavenLocal()
mavenCentral()
flatDir {
dirs \'libs\'
}
}
并在dependencies 节点添加如下声明
compile fileTree(dir: \'libs\', include: \'*.aar\')
4.附上代码：
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.provider.MediaStore;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Point;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
public class MainActivity extends Activity {
static final int REQUEST_OPEN_IMAGE = 1;
String mCurrentPhotoPath;
Bitmap mBitmap;
ImageView mImageView;
int touchCount = 0;
Point tl;
Point br;
boolean targetChose = false;
ProgressDialog dlg;
private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
switch (status) {
case LoaderCallbackInterface.SUCCESS:
{
//Log.i(TAG, "OpenCV loaded successfully");
} break;
default:
{
super.onManagerConnected(status);
} break;
}
}
};
@Override
public void onResume()
{
super.onResume();
if (!OpenCVLoader.initDebug()) {
Log.d("OpenCV", "Internal OpenCV library not found. Using OpenCV Manager for initialization");
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
} else {
Log.d("OpenCV", "OpenCV library found inside package. Using it!");
mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mImageView = (ImageView) findViewById(R.id.imgDisplay);
dlg = new ProgressDialog(this);
tl = new Point();
br = new Point();
// if (!OpenCVLoader.initDebug()) {
// Handle initialization error
//}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
int scaleFactor = 1;
private void setPic() {
int targetW = 720;//mImageView.getWidth();
int targetH = 1128;//mImageView.getHeight();
Log.i(">>>>>", "targetW="+targetW);
Log.i(">>>>>", "targetH=" + targetH);
BitmapFactory.Options bmOptions = new BitmapFactory.Options();
bmOptions.inJustDecodeBounds = true;
BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);
int photoW = bmOptions.outWidth;
int photoH = bmOptions.outHeight;
Log.i(">>>>>", "photoW="+photoW);
Log.i(">>>>>", "photoH=" + photoH);
scaleFactor = Math.max(photoW / targetW, photoH / targetH)+1;
Log.i(">>>>>", "photoW / targetW="+(photoW / targetW));
Log.i(">>>>>", "photoH / targetH="+(photoH / targetH));
bmOptions.inJustDecodeBounds = false;
bmOptions.inSampleSize = scaleFactor;
bmOptions.inPurgeable = true;
mBitmap = BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);
mImageView.setImageBitmap(mBitmap);
Log.i(">>>>>", "mBitmap.getWidth()="+mBitmap.getWidth());
Log.i(">>>>>", "mBitmap.getHeight()=" + mBitmap.getHeight());
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case REQUEST_OPEN_IMAGE:
if (resultCode == RESULT_OK) {
Uri imgUri = data.getData();
String[] filePathColumn = { MediaStore.Images.Media.DATA };
Cursor cursor = getContentResolver().query(imgUri, filePathColumn,
null, null, null);
cursor.moveToFirst();
int colIndex = cursor.getColumnIndex(filePathColumn[0]);
mCurrentPhotoPath = cursor.getString(colIndex);
cursor.close();
setPic();
}
break;
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
switch (id) {
case R.id.action_open_img:
Intent getPictureIntent = new Intent(Intent.ACTION_GET_CONTENT);
getPictureIntent.setType("image/*");
Intent pickPictureIntent = new Intent(Intent.ACTION_PICK,
MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
Intent chooserIntent = Intent.createChooser(getPictureIntent, "Select Image");
chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, new Intent[] {
pickPictureIntent
});
startActivityForResult(chooserIntent, REQUEST_OPEN_IMAGE);
return true;
case R.id.action_choose_target:
if (mCurrentPhotoPath != null)
targetChose = false;
mImageView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
int cx = (mImageView.getWidth()-mBitmap.getWidth())/2;
int cy = (mImageView.getHeight()-mBitmap.getHeight())/2;
if (event.getAction() == MotionEvent.ACTION_DOWN) {
if (touchCount == 0) {
tl.x = event.getX();//300;//
tl.y = event.getY();//300;//
touchCount++;
}
else if (touchCount == 1) {
br.x = event.getX();//1100;//
br.y = event.getY();//1200;//
Paint rectPaint = new Paint();
rectPaint.setARGB(255, 255, 0, 0);
rectPaint.setStyle(Paint.Style.STROKE);
rectPaint.setStrokeWidth(3);
Bitmap tmpBm = Bitmap.createBitmap(mBitmap.getWidth(),
mBitmap.getHeight(), Bitmap.Config.RGB_565);
Canvas tmpCanvas = new Canvas(tmpBm);
tmpCanvas.drawBitmap(mBitmap, 0, 0, null);
tmpCanvas.drawRect(new RectF((float) tl.x, (float) tl.y, (float) br.x, (float) br.y),
rectPaint);
mImageView.setImageDrawable(new BitmapDrawable(getResources(), tmpBm));
targetChose = true;
touchCount = 0;
mImageView.setOnTouchListener(null);
}
}
return true;
}
});
return true;
case R.id.action_cut_image:
if (mCurrentPhotoPath != null && targetChose) {
new ProcessImageTask().execute();
targetChose = false;
}
return true;
}
return super.onOptionsItemSelected(item);
}
private class ProcessImageTask extends AsyncTask<Integer, Integer, Integer> {
Mat img;
Mat foreground;
@Override
protected void onPreExecute() {
super.onPreExecute();
dlg.setMessage("Processing Image...");
dlg.setCancelable(false);
dlg.setIndeterminate(true);
dlg.show();
}
@Override
protected Integer doInBackground(Integer... params) {
//Mat img = new Mat(mBitmap.getHeight(), mBitmap.getHeight(), CvType.CV_8UC3);
//Utils.bitmapToMat(mBitmap, img);
long ll = System.currentTimeMillis();
Log.i(">>>>>", "start="+ll);
img = Imgcodecs.imread(mCurrentPhotoPath);
Imgproc.resize(img, img, new Size(img.cols()/scaleFactor, img.rows()/scaleFactor));
Log.i(">>>>>", "11111=" + System.currentTimeMillis()+"@@@@@"+(System.currentTimeMillis()-ll));
Mat background = new Mat(img.size(), CvType.CV_8UC3,
new Scalar(255, 255, 255));
Mat firstMask = new Mat();
Mat bgModel = new Mat();
Mat fgModel = new Mat();
Mat mask;
Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(Imgproc.GC_PR_FGD));
Mat dst = new Mat();
Rect rect = new Rect(tl, br);
Log.i(">>>>>", "22222="+System.currentTimeMillis()+"@@@@@"+(System.currentTimeMillis()-ll));
Imgproc.grabCut(img, firstMask, rect, bgModel, fgModel,
1, Imgproc.GC_INIT_WITH_RECT);
Log.i(">>>>>", "33333=" + System.currentTimeMillis() + "@@@@@" + (System.currentTimeMillis() - ll));
Core.compare(firstMask, source, firstMask, Core.CMP_EQ);
Log.i(">>>>>", "44444=" + System.currentTimeMillis() + "@@@@@" + (System.currentTimeMillis() - ll));
foreground = new Mat(img.size(), CvType.CV_8UC3,
new Scalar(255, 255, 255));
/////
img.copyTo(foreground);
Imgproc.blur(foreground, foreground, new Size(20, 20));
Log.i(">>>>>", "55555=" + System.currentTimeMillis()+"@@@@@"+(System.currentTimeMillis()-ll));
/////
img.copyTo(foreground, firstMask);
Log.i(">>>>>", "66666=" + System.currentTimeMillis()+"@@@@@"+(System.currentTimeMillis()-ll));
firstMask.release();
source.release();
bgModel.release();
fgModel.release();
Imgcodecs.imwrite(mCurrentPhotoPath + ".png", foreground);
return 0;
}
@Override
protected void onPostExecute(Integer result) {
super.onPostExecute(result);
Bitmap jpg = BitmapFactory
.decodeFile(mCurrentPhotoPath + ".png");
mImageView.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
mImageView.setAdjustViewBounds(true);
mImageView.setPadding(2, 2, 2, 2);
mImageView.setImageBitmap(jpg);
mImageView.invalidate();
dlg.dismiss();
}
}
}
5.完整工程可以在GITHUB上看到
https://github.com/blogercn/backgroundblur
6.用到的关健函数解析：
a.Imgproc.grabCut,抠动，抠出前景
b.Imgproc.blur,对背景模糊处理
c.copyTo.背景背景合并图像
7.效果如下：
