Java – Return rate of investment in OpenCV from Android

I want to use ROI in OpenCV for Android.

Is this the correct code?

Mat image = new Mat();
Mat imageRIO = new Mat();
Rect roi = new Rect(300, 50, 50, 10);

public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
    image = inputFrame.gray();

image.submat(roi);  set roi
    image.copyTo(imageRIO);
    return imageRIO;
 }

I’m not sure exactly what you’re trying to do, but submat() returns a Mat you need and you didn’t assign it to anything. image.copyTo() copies image instead of the subpad you extracted in the previous line.

You can simply do this:

Rect roi = new Rect(300, 50, 50, 10);

public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
    return new Mat(inputFrame.gray(), roi);
}