![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/308876/image.jpeg)
How to draw line in the image through the image processing
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Seunghyuk Lee
on 3 Jun 2020
Commented: Seunghyuk Lee
on 4 Jun 2020
After conducting the evaporator viusalization experiment, want to procced image processing by matlab and found out boundary line between liquid refrigerant and vapor refrigerant. I have tried it with binarize and threshold but didnt get any satisfying result.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/308825/image.jpeg)
here shows my code and the current problem is that i cant get any clear boundary as i can see in the picture with own eyes.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/308828/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/308831/image.png)
i'd like to ask for some advice to get through this problem
6 Comments
Image Analyst
on 4 Jun 2020
Can you use polarizers in front of your light and your camera? Rotate the one in front of the camera lens until all the spurious reflections are eliminated. It will be much easier to process without all those reflections in there.
Accepted Answer
Rafael S.T. Vieira
on 3 Jun 2020
Edited: Rafael S.T. Vieira
on 3 Jun 2020
Glad to help. I've obtained that image using the Gimp editor, but, it is possible to achieve a similar result in Matlab with:
image = imread("myImage.jpeg");
A = imadjust(image, [0.2 0.8]); % adjusting color levels to enhance the image
M = edge(A(:,:,1), 'sobel') | edge(A(:,:,2), 'sobel') | edge(A(:,:,3), 'sobel'); % sobel to detect edges
N = imdilate(M,ones(5)); % dilate to obtain wider edges
O = bwareaopen(N, 1000); % to remove elements with pixel area smaller than 1000 pixels
imshowpair(image,O,'montage')
I've looked at the image histogram and used the imtool for deciding the previous parameters. The result is the following (you could try adjusting the parameters of any of these functions for obtaining a better result):
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/309476/image.jpeg)
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