OpenCV Error: Assertion failed in watershed

asked 2015-06-25 01:42:46 -0600

Nina gravatar image
cv::Mat image;
UIImageToMat(input, image, false);
cv::Mat binary;
cv::cvtColor(image, binary, COLOR_BGR2GRAY);
cv::threshold(binary, binary, 100, 255, THRESH_BINARY);

    // Eliminate noise and smaller objects
cv::Mat fg;

    // Identify image pixels without objects
cv::Mat bg;
cv::threshold(bg,bg,1, 128,cv::THRESH_BINARY_INV);

    // Create markers image
markers= fg+bg;
    // Create watershed segmentation object
WatershedSegmenter segmenter;

cv::Mat result = segmenter.process(image);
return MatToUIImage(result);

class WatershedSegmenter{
cv::Mat markers;
void setMarkers(cv::Mat& markerImage)
markerImage.convertTo(markers, CV_32S);

cv::Mat process(cv::Mat &image)
cv::watershed(image, markers);
return markers;

While learning about OpenCV I came across the topic of segmentation, and found a thread here. I tried my hand at the provided answer and got the following error,

OpenCV Error: Assertion failed (src.type() == CV_8UC3 && dst.type() == CV_32SC1) in watershed, file /Users/siva/working/opencv/modules/imgproc/src/segmentation.cpp, line 147

And couldn't figure out a solution as I'm new to this topic. Any suggestions/solutions please?

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Same here.

My code used to work with OpenCV 2.4 but I need one of the new features of OpenCV 3.0, when I recompiled the code just failed in that assertion.

Trying to convert the grey scaled image back to RGB works to pass the failure of that assertion but OpenCV fails later so it isn't any workaround.

Is there any fix for this?

icvidal gravatar imageicvidal ( 2015-07-16 07:37:33 -0600 )edit

I have a similar issue when using watershed from python: markers = cv2.watershed(im, img2)

error: C:\projects\opencv-python\opencv\modules\imgproc\src\segmentation.cpp:161: error: (-215) src.type() == (((0) & ((1 << 3) - 1)) + (((3)-1) << 3)) && dst.type() == (((4) & ((1 << 3) - 1)) + (((1)-1) << 3)) in function cv::watershed

what does this error mean?

bayesfactor gravatar imagebayesfactor ( 2018-03-12 15:56:08 -0600 )edit

Have you found the solution?

muhammad gravatar imagemuhammad ( 2019-11-03 15:52:35 -0600 )edit