I want measuring angle in image

I have picture as binary image I want find angle of picture in top left,top right,bottom right,bottom left from axis X at 0 degree whirl as circle completely, 360 degree. red point is point want to know angle in picture

**red point I create in Photoshop

[KSSV]

Same question: https://in.mathworks.com/matlabcentral/answers/324677-i-want-to-find-angle-in-picture.

I am closing the other one and keeping the present one.

[Adisorn Phanukthong]

I can't see this link

Answer 1

[Image Analyst]

See Roger Stafford's answer: https://www.mathworks.com/matlabcentral/answers/120930-calculate-an-angle-and-distance-from-three-points#answer_127755

and Cleve's blog: http://blogs.mathworks.com/cleve/2016/04/11/the-eigenwalker-model-of-the-human-gait/

[Adisorn Phanukthong]

I want as code mathlab. Can you help me please .

[Image Analyst]

Roger's link had the code. Just use it on each of your red dots, and centroid, which I presume you have, to find the angles.

If you don't have the centroid, see my Image Segmentation Tutorial http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862. Basically, if you have the binary image, in short, to find the centroid, it's

binaryImage = bwareafilt(binaryImage, 1); % Extract largest blob.
labeledImage = bwlabel(binaryImage);
props = regionprops(labeledImage, 'Centroid');
xCentroid = props(1).Centroid(1);
yCentroid = props(1).Centroid(2);

It's not exactly clear the rules for finding your red dots. I mean, they could jsut as easily be moved around the outline a little bit and I wouldn't know which is correct/best. Since you know the rules, not me, just use your own code to find the red dots.