OpenCV Assertion failed with ROI

Question

I'm trying to get every circle in a new window, however I get this error; the error

I don't know why that happends. The Rect object gives normal values: rect values

Code:

void scanCircle(int x, int y, int h, Mat src, int rad) {
try {
    Rect region = Rect(x, y, x + h, y + h);
    Mat roi = src(region).clone();
}
catch (...) {
    cout << "Error";
}

}

With Google I found this one: OpenCv assertion failed

However I don't see whats wrong.

Answer 1

The error means that your rectangle region goes out of the bounds of the image src .

In fact you're constructing the rectangle with wrong values, it should be:

Rect region(x, y, h, h);

since 3rd and 4th arguments are width and height, not the coordinates of the bottom right point.

Or you can use the constructor that accepts top-left and bottom-right points:

Rect region(Point(x,y), Point(x+h, y+h));