在android平台上利用opencv进行图像处理之边沿检测

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由于项目的需要，这几天开始接触opencv，要在android平台上利用opencv进行图像处理。以下是这几天的成果：

运行结果如下：

原始图片：



处理后的图片：



Java代码：

package com.cdq.opencvtest;

import java.io.File;

import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Size;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity
{

private ImageView iv = null;
private Button btn1 = null;
private Button btn2 = null;
String tag="MainActivity";
//OpenCV类库加载并初始化成功后的回调函数
private BaseLoaderCallback mLoader = new BaseLoaderCallback(this)
{

@Override
public void onManagerConnected(int status)
{
switch (status)
{
case LoaderCallbackInterface.SUCCESS:
{
}break;
default:
{
super.onManagerConnected(status);
}break;
}
}

};
@Override
protected void onResume()
{
super.onResume();
//通过OpenCV引擎服务加载并初始化OpenCV类库，所谓OpenCV引擎服务即是 OpenCV Manager
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_9, this,mLoader);
}
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
iv = (ImageView) findViewById(R.id.iv);
btn1 = (Button) findViewById(R.id.btn1);
btn2 = (Button) findViewById(R.id.btn2);
Bitmap bitmap = BitmapFactory.decodeFile("/sdcard/face8.jpg");
iv.setImageBitmap(bitmap);
btn1.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View arg0)
{
Mat img = Highgui.imread("/sdcard/face8.jpg", 0);
Size dSize = new Size((double) img.width(), (double) img.height());
Mat img2 = new Mat(dSize, CvType.CV_8SC1);
Mat img3 = new Mat();
img.convertTo(img2, CvType.CV_8SC1);
Imgproc.Canny(img, img3, 123, 250);
boolean flag = Highgui.imwrite("/sdcard/new.jpg", img3);
Log.i(tag, "onClick");
if (flag)
{
Log.i(tag, "flag");
File file = new File("/sdcard/new.jpg");
if (file.exists())
{
Bitmap bitmap2 = BitmapFactory.decodeFile("/sdcard/new.jpg");
iv.setImageBitmap(bitmap2);
}
}
else
{
Toast.makeText(getApplicationContext(), "图片写入失败",
Toast.LENGTH_SHORT).show();
}

}
});
btn2.setOnClickListener(new OnClickListener()
{

@Override
public void onClick(View arg0)
{
Bitmap bitmap = BitmapFactory.decodeFile("/sdcard/face8.jpg");
iv.setImageBitmap(bitmap);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}

AndroidMenifest.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.cdq.opencvtest"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="14" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.cdq.opencvtest.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>
</application>

</manifest>

布局文件：

<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context=".MainActivity" >

<TableLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
>

<ImageView
android:id="@+id/iv"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="9" />

<TableRow
android:id="@+id/tableRow1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >

<Button
android:id="@+id/btn1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="处理"
android:layout_weight="1"/>

<Button
android:id="@+id/btn2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="恢复"
android:layout_weight="1"/>
</TableRow>

</TableLayout>

</LinearLayout>

实践过程中，一直有个问题纠结了我很久——java.lang.UnsatisfiedLinkError: Native method not found: org.opencv.highgui.Highgui.imread_0:(Ljava/lang/String;I)。在网上看了很多资料后，才明白其实是程序没有加载opencv类库。于是我加入了以下代码后，问题得到了解决：

//OpenCV类库加载并初始化成功后的回调函数
private BaseLoaderCallback mLoader = new BaseLoaderCallback(this)
{

@Override
public void onManagerConnected(int status)
{
switch (status)
{
case LoaderCallbackInterface.SUCCESS:
{
}break;
default:
{
super.onManagerConnected(status);
}break;
}
}

};
@Override
protected void onResume()
{
super.onResume();
//通过OpenCV引擎服务加载并初始化OpenCV类库，所谓OpenCV引擎服务即是 OpenCV Manager
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_9, this,mLoader);
}