5

I've been trying to process an image as soon as the picture was taken i.e. in the onPictureTaken() callback. As it was to my understanding I should convert the byte array to an OpenCV matrix, but the entire app freezes when I try to do that. Basically all I did was this:

@Override
public void onPictureTaken(byte[] bytes, Camera camera) {
    Log.w(TAG, "picture taken!");

    if (bytes != null) {
        Bitmap image = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
        Mat matImage = new Mat();

        // This is where my app freezes.
        Utils.bitmapToMat(image, matImage);

        Log.w(TAG, matImage.dump());
    }

    mCamera.startPreview();
    mCamera.setPreviewCallback(this);
}

Does anyone know why it freezes and how to solve it?

Note: I've used the OpenCV4Android tutorial 3 as a base.

Update 1: I've also tried to parste the bytes (without any success) as follows:

Mat mat = Imgcodecs.imdecode(
    new MatOfByte(bytes), 
    Imgcodecs.CV_LOAD_IMAGE_UNCHANGED
);

Update 2: Supposedly this should work, it did not for me though.

Mat mat = new Mat(1, bytes.length, CvType.CV_8UC3);
mat.put(0, 0, bytes);

Nor did this variant:

Bitmap image = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
Mat mat = new Mat(image.getHeight(), image.getWidth(), CvType.CV_8UC1);
mat.put(0, 0, bytes);

Update 3: This did not work for me either:

Mat mat = new MatOfByte(bytes);
Mathijs
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1 Answers1

1

I've got some help of a colleague of mine. He managed to fix the problem by doing the following:

BitmapFactory.Options opts = new BitmapFactory.Options(); // This was missing.
Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length, opts);

Mat mat = new Mat();
Utils.bitmapToMat(bitmap, mat);

// Note: when the matrix is to large mat.dump() might also freeze your app.
Log.w(TAG, mat.size());

Hopefully this'll help all of you who are also struggling with this.

Mathijs
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