I know a disk structuring element can be created in MATLAB as following:
se=strel('disk',4);
0 0 1 1 1 0 0
0 1 1 1 1 1 0
1 1 1 1 1 1 1
1 1 1 1 1 1 1
1 1 1 1 1 1 1
0 1 1 1 1 1 0
0 0 1 1 1 0 0
Is there any function or method or any other way of creating the structuring element same as above in opencv. I know we can manually create it using loops but I just want to know if some function exist for that.
3 Answers
The closest one (not the exact same) you can get in OpenCV is by calling getStructuringElement():
int sz = 4;
cv::Mat se = cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(2*sz-1, 2*sz-1));
, which gives the matrix with values
[0, 0, 0, 1, 0, 0, 0;
0, 1, 1, 1, 1, 1, 0;
1, 1, 1, 1, 1, 1, 1;
1, 1, 1, 1, 1, 1, 1;
1, 1, 1, 1, 1, 1, 1;
0, 1, 1, 1, 1, 1, 0;
0, 0, 0, 1, 0, 0, 0]
def estructurant(radius):
kernel = np.zeros((2*radius+1, 2*radius+1) ,np.uint8)
y,x = np.ogrid[-radius:radius+1, -radius:radius+1]
mask = x**2 + y**2 <= radius**2
kernel[mask] = 1
kernel[0,radius-1:kernel.shape[1]-radius+1] = 1
kernel[kernel.shape[0]-1,radius-1:kernel.shape[1]-radius+1]= 1
kernel[radius-1:kernel.shape[0]-radius+1,0] = 1
kernel[radius-1:kernel.shape[0]-radius+1,kernel.shape[1]-1] = 1
return kernel
try this
You could also use skimage.morphology.disk, which produces a symmetric result (unlike cv2.getStructuringElement):
>>> disk(4)
array([[0, 0, 0, 0, 1, 0, 0, 0, 0],
[0, 0, 1, 1, 1, 1, 1, 0, 0],
[0, 1, 1, 1, 1, 1, 1, 1, 0],
[0, 1, 1, 1, 1, 1, 1, 1, 0],
[1, 1, 1, 1, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 1, 1, 0],
[0, 1, 1, 1, 1, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 1, 1, 0, 0],
[0, 0, 0, 0, 1, 0, 0, 0, 0]], dtype=uint8)
