OpenCV getPerspectiveTransform和warpPerspective Java [英] OpenCV getPerspectiveTransform and warpPerspective Java
问题描述
我目前有一个 ArrayList< MatOfPoint>
,它存储图像的轮廓并检索出最大的轮廓,这是我对warpPerspective的目标。
I current have a ArrayList<MatOfPoint>
which stores the contours of the image and have retrieved the largest contour which is my target for the warpPerspective.
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);
我在如何使用getPerspectiveTransform然后应用warpPerspective更改图像方面遇到了麻烦它将适合450x450的图像。
I am having trouble on how to use the getPerspectiveTransform and then applying the warpPerspective to change the image so that it will fit within a 450x450 image.
我在python中找到了一个非常好的例子,不过我对它不是很熟悉有人可以解释我会如何纠正在java?
I found an pretty good example of this in python, however I am not very familiar with it can someone explain how I would do rectify in java?
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
推荐答案
简介:使用wrapPerspective我们需要使用getPerspectiveTransform来计算包裹垫:Mat src和Mat dst。那些是你的轮廓的src(左下角,右下角,左上角,右上角)的MarOfPoints2f和相应的mat dst(0,0; 0,449; 449,0; 449,449)(所以图像将是450x450 - 如果这是错误的,请更正我。)
Intro: to make use of wrapPerspective we need to calculate wrapping mat using getPerspectiveTransform takes: Mat src and Mat dst. Those are MarOfPoints2f with src(bottom-left, bottom-right, top-left, top-right) of your contour and corresponding mat dst( 0,0 ; 0,449 ; 449,0 ; 449,449) (So the image will be 450x450 - If this is wrong please correct me).
解决方案在Java中用于opencv 3将是:
Solution in Java for opencv 3 would be:
-
获得点数
矩形轮廓为 MatOfPoints2f ,我们需要按上面所述对点进行排序:
Get points sorted Having rectangular contour as MatOfPoints2f approx we need to sort the points as written above:
//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
Prepare Mat src and 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
Use getPerspectiveTransform and 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。
I have just finished doing similar project so I am sure this can be done better but it is a working solution if anyone needs one.
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