Get all points inside a rectangle using opencv findcontour method

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I want to find all points in the rectangle. But when i use findContour method in opencv, it actually finds points in the lines drawn ( Not points inside the rectangle). I verified using drawcontour method ( even if we use thickness as -1, it draws lines ).

How can i find points inside the smaller rectangle using findContour method ?

//srcMatrix create
Mat srcMat = new Mat();
srcMat.create(100, 100, CvType.8UC3);

// create a canny matrix
Mat mCanny = new Mat();

// Make it to sizeof srcMatrix and 
// make channel to 1
mCanny.create( srcMat.cols(), srcMat.rows, CvType.8UC1) 

// clear it
mCanny.setTo(new Scalar(0));

// draw a border   rectangle on the mcanny
Core.rectangle(mCanny, 
        new Point(0,0),
            new Point(100, 100),
            new Scalar(255));

// draw a rectangle
Core.rectangle(mCanny, 
        new Point(25,25),
            new Point(50, 50),
            new Scalar(255));

// make it binary image
Imgproc.cvtColor(mCanny , mCanny , Imgproc.COLOR_RGB2GRAY);

// make it blur
Imgproc.blur( mCanny, mCanny, new Size(3,3));

//find canny
Imgproc.Canny(mCanny ,mCanny, 2,4); 

/// find Contour
List<MatOfPoint> contours = new ArrayList<MatOfPoint>();
Imgproc.findContours(mCanny,
            contours, new Mat(), Imgproc.RETR_EXTERNAL, Imgproc.CHAIN_APPROX_SIMPLE);