Question

我目前有一个ArrayList<MatOfPoint>存储图像的轮廓，并检索出最大的轮廓，这是我对warpPerspective的目标。

List<MatOfPoint> contours = new ArrayList<MatOfPoint>();
Imgproc.findContours(matOut, contours, new Mat(), Imgproc.RETR_LIST, Imgproc.CHAIN_APPROX_SIMPLE);

sort(contours);
MatOfPoint2f  m2f = MatOfPoint2f(contours.get(0).toArray());
double arc = Imgproc.arcLength(m2f, true);
MatOfPoint2f approx = new MatOfPoint2f();
Imgproc.approxPolyDP(m2f, approx, arc*0.02, true);

我无法使用getPerspectiveTransform，然后应用warpPerspective来更改图像，使其适合450x450的图像。

我在python中找到了一个相当不错的例子，但我对它不是很熟悉有人可以解释我如何在java中纠正它？

def rectify(h):
    ''' this function put vertices of square we got, in clockwise order '''
    h = h.reshape((4,2))
    hnew = np.zeros((4,2),dtype = np.float32)

    add = h.sum(1)
    hnew[0] = h[np.argmin(add)]
    hnew[2] = h[np.argmax(add)]

    diff = np.diff(h,axis = 1)
    hnew[1] = h[np.argmin(diff)]
    hnew[3] = h[np.argmax(diff)]

    return hnew

这是源链接：https://github.com/abidrahmank/OpenCV2-Python/blob/master/OpenCV_Python_Blog/sudoku_v_0.0.6/sudoku.py

Answer 1

简介：要使用wrapPerspective，我们需要使用getPerspectiveTransform来计算包装垫：Mat src和Mat dst。那些是你的轮廓的src（左上角，右上角，左下角，右下角）和对应的mat dst（0,0; 0,449; 449,0; 449,449）的MarOfPoints2f（所以图像将是450x450 - 如果这是错的，请纠正我。）

用于opencv 3的Java中的

解决方案将是：

获取点数排序矩形轮廓为 MatOfPoints2f约，我们需要对点进行排序，如上所述：

//calculate the center of mass of our contour image using moments
Moments moment = Imgproc.moments(approx.get(0));
int x = (int) (moment.get_m10() / moment.get_m00());
int y = (int) (moment.get_m01() / moment.get_m00());

//SORT POINTS RELATIVE TO CENTER OF MASS 
Point[] sortedPoints = new Point[4];

double[] data;
int count = 0;
for(int i=0; i<approx.get(0).rows(); i++){
    data = approx.get(0).get(i, 0);
    double datax = data[0];
    double datay = data[1];
    if(datax < x && datay < y){
        sortedPoints[0]=new Point(datax,datay);
        count++;
    }else if(datax > x && datay < y){
        sortedPoints[1]=new Point(datax,datay);
        count++;
    }else if (datax < x && datay > y){
        sortedPoints[2]=new Point(datax,datay);
        count++;
    }else if (datax > x && datay > y){
        sortedPoints[3]=new Point(datax,datay);
        count++;
    }
}

准备Mat src和det

        MatOfPoint2f src = new MatOfPoint2f(
                sortedPoints[0],
                sortedPoints[1],
                sortedPoints[2],
                sortedPoints[3]);

        MatOfPoint2f dst = new MatOfPoint2f(
                new Point(0, 0),
                new Point(450-1,0),
                new Point(0,450-1),
                new Point(450-1,450-1)      
                );

使用getPerspectiveTransform和wrapPrespective

    Mat warpMat = Imgproc.getPerspectiveTransform(src,dst);
    //This is you new image as Mat
    Mat destImage = new Mat();
    Imgproc.warpPerspective(originalImg, destImage, warpMat, originalImg.size());

我刚刚完成了类似的项目，所以我相信这可以做得更好，但如果有人需要，这是一个有效的解决方案。

OpenCV getPerspectiveTransform和warpPerspective Java

1 个答案: