在Android中使用Opencv进行边缘检测

Question

Am trying to use opencv in my android project. Here is a complete list of events i did over the past few weeks:

1- I used my mobile phone camera to take a picture stored it as bitmap
2- Ran face detection on it
3- Now i was supposed to use android opencv to highlight the edges in the face detection bitmap

I do not know much about ndk stuff. All I did was downloaded the android opencv sdk imported into my project workspace used this as library project for my application and am using the following code in my android application:

 Bitmap canny_image = Bitmap.createBitmap(bmFace.getWidth(), bmFace.getHeight(), Config.ARGB_8888);
        canny_image = bmFace.copy(Config.ARGB_8888, true); 
        Mat mImg = new Mat();
        Utils.bitmapToMat(canny_image,mImg);

        //Converting to grayscale
        Mat mGray = new Mat(mImg.rows(), mImg.cols(), CvType.CV_8UC1, new Scalar(0));
        Imgproc.cvtColor(mImg , mGray, Imgproc.COLOR_BGRA2GRAY, 4); 
        //Applying Canny
        Imgproc.Canny(mGray, mGray, 80, 90);

        //Converting back to 4 channel image
        Imgproc.cvtColor(mGray , mImg, Imgproc.COLOR_GRAY2RGBA, 4); 
        canny_image.recycle();
        System.gc();
        canny_image = Bitmap.createBitmap(mImg.cols(), mImg.rows(), Bitmap.Config.ARGB_8888); 
        Utils.matToBitmap(mImg, canny_image); 

However the logcat is showing unsatisfied link error. Now using the documentation from here .

In this link there is a point:

If your application project doesn’t have a JNI part, just copy the corresponding OpenCV native libs from <OpenCV-2.4.6-android-sdk>/sdk/native/libs/<target_arch> to your project directory to folder libs/<target_arch>.

In case of the application project with a JNI part, instead of manual libraries copying you need to modify your Android.mk file: add the following two code lines after the "include $(CLEAR_VARS)" and before "include path_to_OpenCV-2.4.6-android-sdk/sdk/native/jni/OpenCV.mk"

I did the same. In my application i made a folder libs and copied all the .so and .h files in the /sdk/native/libs/

but then again my library project does not contain the application.mk and android.mk files. Am totally messed up how to use opencv in my android application. I thought the linking problem was due to the fact that i have not loaded the library in my code but again when i use this code in my application it gives an exception:

 private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
            case LoaderCallbackInterface.SUCCESS:
            {
                Log.i(TAG, "OpenCV loaded successfully");
                mOpenCvCameraView.enableView();
            } break;
            default:
            {
                super.onManagerConnected(status);
            } break;
        }
    }
};

Referenced from the same link as i mentioned above. Please experts help me on this. I need some serious help. Been stuck here for like almost a week. How can i successfully use opencv in my android application. What am i missing?

Answer 1

This error is shown when you are calling a library before initializing it. Refer here : Android UnsatisfiedLinkError with OpenCV 2.4.2 . Refer to the comment thread beneath the correct answer. So let the library initialise and then add whatever you wish to do beneath "Log.i(TAG, "OpenCV loaded successfully");"