Android OpenCV实现图片叠加，水印

关于如何用纯OpenCV实现图片叠加的例子实在是太少，太多的是使用 C++,JNI实现的，如果要用C++的话，我们为啥不转行做C++

下面的例子基于 Android JavaCV实现了在im_beauty 美女图片上添加im_flower3 小花图片并显示

Android OpenCV实现图片叠加，水印_第1张图片

需要在res/drawable目录下放两个文件 im_beauty, im_flower3 注意im_flower3一定要比im_beauty图片尺寸要下小

package com.KyleOpencvImageAdd;import org.opencv.android.BaseLoaderCallback;import org.opencv.android.LoaderCallbackInterface;import org.opencv.android.OpenCVLoader;import org.opencv.android.Utils;import org.opencv.core.Mat;import org.opencv.core.Rect;import android.os.Bundle;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;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;public class MainActivity extends Activity implements OnClickListener {private Mat mat1,mat2;private ImageView iv1,iv2;//用于显示两张图片叠加private ImageView iv3;private Button btn;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//初始化图片显示iv1=(ImageView)findViewById(R.id.imageView1); iv1.setImageResource(R.drawable.im_beauty); iv2=(ImageView)findViewById(R.id.imageView2); iv2.setImageResource(R.drawable.im_flower3); iv3=(ImageView)findViewById(R.id.imageView3);btn=(Button)findViewById(R.id.button1);btn.setOnClickListener(this);}@Overridepublic 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;}    private BaseLoaderCallback  mLoaderCallback = new BaseLoaderCallback(this) {@Override        public void onManagerConnected(int status) {            switch (status) {                case LoaderCallbackInterface.SUCCESS:                {                    Log.i("", "OpenCV loaded successfully");                                 } break;                default:                {                    super.onManagerConnected(status);                } break;            }        }    };@Overrideprotected void onResume() {// TODO Auto-generated method stubsuper.onResume();//初始化函数库OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_3, this, mLoaderCallback);}@Overridepublic void onClick(View arg0) {// 初始化数据mat1 = new Mat();mat2 = new Mat();Mat mat1Sub = new Mat();// 加载图片Bitmap bt1 = BitmapFactory.decodeResource(getResources(),R.drawable.im_beauty);Bitmap bt2 = BitmapFactory.decodeResource(getResources(),R.drawable.im_flower3);Bitmap bt3 = null;// 转换数据Utils.bitmapToMat(bt1, mat1);Utils.bitmapToMat(bt2, mat2);/** 方法一加权 高级方式 可实现水印效果*********/// mat1Sub=mat1.submat(0, mat2.rows(), 0, mat2.cols());// Core.addWeighted(mat1Sub, 1, mat2, 0.3, 0., mat1Sub);/** 方法二 求差 ********/// submat(y坐标, 图片2的高, x坐标，图片2的宽);// mat1Sub=mat1.submat(0, mat2.rows(), 0, mat2.cols());// mat2.copyTo(mat1Sub);/*** 方法三兴趣区域裁剪 **/// 定义感兴趣区域Rect(x坐标，y坐标,图片2的宽，图片2的高)Rect rec = new Rect(0, 0, mat2.cols(), mat2.rows());// submat(y坐标, 图片2的高, x坐标，图片2的宽);mat1Sub = mat1.submat(rec);mat2.copyTo(mat1Sub);        //转化为android识别的图像数据注意bt3的宽高要和mat1一至bt3 = Bitmap.createBitmap(mat1.cols(), mat1.rows(), Config.RGB_565);Utils.matToBitmap(mat1, bt3);iv3.setImageBitmap(bt3);}}

处理上 bitmap 与mat 的一定要注意图片的宽高一致不然容易 Exception

/cv::error()(17079): OpenCV Error: Assertion failed (src.dims == 2 && info.height == (uint32_t)src.rows && info.width ==

(uint32_t)src.cols) in void Java_org_opencv_android_Utils_nMatToBitmap2(JNIEnv*, jclass, jlong, jobject, jboolean), file

/home/reports/ci/slave/50-SDK/opencv/modules/java/generator/src/cpp/utils.cpp, line 97

/org.opencv.android.Utils(17079): nMatToBitmap catched cv::Exception: /home/reports/ci/slave/50-

SDK/opencv/modules/java/generator/src/cpp/utils.cpp:97: error: (-215) src.dims == 2 && info.height == (uint32_t)src.rows &&

info.width == (uint32_t)src.cols in function void Java_org_opencv_android_Utils_nMatToBitmap2(JNIEnv*, jclass, jlong,

jobject, jboolean)

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