I wanted to simply convert a bitmap from Android to a Mat object for OpenCV. This topic is often adressed on Stack Overflow. For example:
convert Mat to Bitmap Opencv for Android ;
convert Bitmap to Mat after capture image using android camera ;
templateMatching mattoBitmap opencv for android
There is even more to find. I followed the instrcutions in this answers, but I'm still unable to get is done the right way.
Minimal code:
//First convert Bitmap to Mat
Mat ImageMat = new Mat ( image.getHeight(), image.getWidth(), CvType.CV_8U, new Scalar(4));
Bitmap myBitmap32 = image.copy(Bitmap.Config.ARGB_8888, true);
Utils.bitmapToMat(myBitmap32, ImageMat);
//Do smth.
Imgproc.cvtColor(ImageMat, ImageMat, Imgproc.COLOR_RGB2GRAY,4);
//Then convert the processed Mat to Bitmap
Bitmap resultBitmap = Bitmap.createBitmap(ImageMat.cols(), ImageMat.rows(),Bitmap.Config.ARGB_8888);;
Utils.matToBitmap(ImageMat, resultBitmap);
//Set member to the Result Bitmap. This member is displayed in an ImageView
mResult = resultBitmap;
(note: image is a Bitmap supplied to this lines of code)
Errors:
08-07 15:13:59.188: E/AndroidRuntime(2115): FATAL EXCEPTION: main
08-07 15:13:59.188: E/AndroidRuntime(2115): java.lang.NoClassDefFoundError: org.opencv.core.Mat
But my imports are:
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
//OpenCV
import org.opencv.android.Utils;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Scalar;
import org.opencv.imgproc.Imgproc;
Would really appreciate any sort of help. Thanks DanS
You only can do your work with OpenCV after it is initialized. So you need to initialize it like that:
1.Create a Callback:
private BaseLoaderCallback mOpenCVCallBack = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
switch (status) {
case LoaderCallbackInterface.SUCCESS:
//DO YOUR WORK/STUFF HERE
break;
default:
super.onManagerConnected(status);
break;
}
}
};
2.You need to initialize the callback in the onResume Method of your Activity:
@Override
protected void onResume() {
super.onResume();
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_8, this,
mOpenCVCallBack);
}
and thats it, i hope it was helpful :D