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Is there any problem in using the same src and dst image in filtering functions?

asked 2014-03-27 05:03:07 -0500

mb gravatar image

Filtering operations can't be done in the same image since the convolution needs points at already processed positions right? And if I update the same image I get that i'm convolutiong using filtered values instead of original ones. The question is: are the opencv functions like GaussianBlur(.), blur(.), medianBlur(.), bilateralBlur(.) and so on safe to this issue? (doeas opencv create a temporary second matrix internally?) In other words Can I set the "src" and "dst" parameters to the same Mat reference?

ps. I'm writing in C++

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answered 2014-03-27 10:41:20 -0500

ajplockyer gravatar image

Yes, src and dst can be the same matrix. The following code works fine:

int main(int argc, char argv[]) {
    cv::Mat test = cv::imread("test.jpg");
    cv::GaussianBlur(test, test, cv::Size(11, 11), 5.0);
    cv::imshow("test", test);
    return 0;
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thanks for replying. Yes it looks fine for blur and GaussianBlur, but for bilateralBlur it gives me this:

OpenCV Error: Assertion failed ((src.type() == CV_8UC1 || src.type() == CV_8UC3) && src.type() == dst.type() && src.size() == dst.size() && != in bilateralFilter_8u, file /build/opencv/src/opencv-2.4.7/modules/imgproc/src/smooth.cpp, line 1925 terminate called after throwing an instance of 'cv::Exception' what(): /build/opencv/src/opencv-2.4.7/modules/imgproc/src/smooth.cpp:1925: error: (-215) (src.type() == CV_8UC1 || src.type() == CV_8UC3) && src.type() == dst.type() && src.size() == dst.size() && != in function bilateralFilter_8u

mb gravatar imagemb ( 2014-03-27 12:50:36 -0500 )edit

Could you link to documentation saying that src and dst can be the same? It would be helpful to know that this is part of the method's contract, and not just an implementation detail dependent on one specific release.

dinosaur gravatar imagedinosaur ( 2016-07-06 17:56:02 -0500 )edit

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Asked: 2014-03-27 05:03:07 -0500

Seen: 6,512 times

Last updated: Mar 27 '14