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watershed algorithm to image with grey background

asked 2017-08-19 06:46:21 -0600

chetanreddy gravatar image

updated 2019-12-09 08:19:47 -0600

Akhil Patel gravatar image

I have an image with grey backgound to which i want to apply watershed algorithm.

But as I am trying to threshold the grey scaled image, the background is also is being converted to white(binary+otsu thresholding).
I thought of applying the grabcut algorithm to my image first then apply watershed.

I have no idea how to implement this.
Any help in this regard would be appreciated?

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please post the code you tried and the sample image

sturkmen gravatar imagesturkmen ( 2017-08-19 07:00:06 -0600 )edit

@sturkmen I have added a sample image

chetanreddy gravatar imagechetanreddy ( 2017-08-19 07:50:41 -0600 )edit

@chetanreddy did you delete your question after accepting answer?

sturkmen gravatar imagesturkmen ( 2017-08-21 08:12:39 -0600 )edit

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answered 2017-08-20 18:58:10 -0600

updated 2017-08-20 19:10:03 -0600

this example program demonstrates using watershed

but you need some preprocessing like below ( add this piece of code to imageSegmentation.cpp line 26)

Mat img_gray;
cvtColor(src, img_gray, cv::COLOR_BGR2HSV);

Mat hsv[3];
split(img_gray, hsv);

img_gray = hsv[2] + hsv[1];
imshow("img_gray", img_gray);
src.setTo(Scalar(0, 0, 0), ~img_gray);
    // ( this code is suitable for bright objects on gray background )

this step will give you the image below

image description

and you will finally get the image below.

image description

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How come your objects are so overly segmented? Using the linked tutorial and following this approach this should not happen :)

StevenPuttemans gravatar imageStevenPuttemans ( 2017-08-21 08:56:06 -0600 )edit
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i am not experienced with watershed. indeed as i do most of the time. i tried to change something with existing code and share the result. i have no deep understanding about what goes here :)

sturkmen gravatar imagesturkmen ( 2017-08-21 09:23:58 -0600 )edit

I will have a look at it tomorrow ๐Ÿ˜€

StevenPuttemans gravatar imageStevenPuttemans ( 2017-08-21 11:47:04 -0600 )edit

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Asked: 2017-08-19 06:46:21 -0600

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Last updated: Aug 21 '17