Using cuda::morphologyex in opencv 3 - opencv

Question

I am working in an opencv project which usese the morphologyex function. Now I am trying to do it with gpu support.
When I compile my program with opencv 3.0 and cuda 7.5 support, it accepts most of the functions (such as cuda::threshold, cuda::cvtcolor,etc) except for morphologyEx. Note that morphologyex is called in opencv 2.4.9 as gpu::morphologyEx.
How can I use this function in OpenCV 3.0 or 3.1? If it isn't supported, is there an alternative to this function?
Actually I am using this function for background detection in nonuniform illumination. I am adding the code to the question. Please suggest me how can I replace the morphologyEx function.
#include <opencv2\opencv.hpp>
using namespace cv;
int main()
{
// Step 1: Read Image
Mat1b img = imread("path_to_image", IMREAD_GRAYSCALE);
// Step 2: Use Morphological Opening to Estimate the Background
Mat kernel = getStructuringElement(MORPH_ELLIPSE, Size(15,15));
Mat1b background;
morphologyEx(img, background, MORPH_OPEN, kernel);
// Step 3: Subtract the Background Image from the Original Image
Mat1b img2;
absdiff(img, background, img2);
// Step 4: Increase the Image Contrast
// Don't needed it here, the equivalent would be cv::equalizeHist
// Step 5(1): Threshold the Image
Mat1b bw;
threshold(img2, bw, 50, 255, THRESH_BINARY);
// Step 6: Identify Objects in the Image
vector<vector<Point>> contours;
findContours(bw.clone(), contours, CV_RETR_LIST, CV_CHAIN_APPROX_NONE);
for(int i=0; i<contours.size(); ++i)
{
// Step 5(2): bwareaopen
if(contours[i].size() > 50)
{
// Step 7: Examine One Object
Mat1b object(bw.size(), uchar(0));
drawContours(object, contours, i, Scalar(255), CV_FILLED);
imshow("Single Object", object);
waitKey();
}
}
return 0;
}
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Thanks to #Roy Falk
After reading the valuable comments and documentation, I felt that morphologyEX function
morphologyEx(img, background, MORPH_OPEN, kernel);
can be replaced by
cv::Ptr<cv::cuda::Filter>morph = cuda::createMorphologyFilter(MORPH_OPEN, out.type(), kernel);
morph->apply(out, bc);
feel free to say if I'm wrong

Answer 1

As noted in the comment above, morphologyex is not in the 3.1 API.
I'm guessing you need to map the invocation as documented in 2.4 documentation to the way it's done in 3.1.
Specifically, morphologyex has the following Parameters:
src Source image. Use cuda::Filter and cuda::Filter::apply
dst Destination image same as above
op Type of a morphological operation. Try cuda::createMorphologyFilter
...etc.
In other words, 2.4 did the operation in one go (morphologyex). In 3.1 you first create a filter using createFooFilter and then call apply filter.
Not really a definitive answer but more of a suggestion, but couldn't really write all this in a comment. Good luck.
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Edit: Try looking at https://github.com/Itseez/opencv/blob/master/samples/gpu/morphology.cpp. It shows how to use cuda::createMorphologyFilter