How to find the distance of a object from centre line of the image.

Sir, I have a binary image with one object. Is it possible to find the distance of the centroid of the object from the center line of the image by using 'regionprop' function? I want to know how can I find 'a' and 'b' in the image. I have attached the image. Thank You.

Answer 1

[Image Analyst]

Just get the centroid and then get the distances

labeledImage = bwlabel(binaryImage);
[rows, columns] = size(binaryImage);
measurements = regionprops(labeledImage, 'Centroid');
b = abs(rows/2 - measurements.Centroid(2));
deltaX = measurements.Centroid(1) - columns/2;
a = sqrt(b^2 + deltaX^2)

[Image Analyst]

regionprops() can give both Centroid which is the centroid based on the shape alone (ignoring the gray levels), and WeightedCentroid which is the centroid taking into account the gray levels at each pixel in the shape.

[Image Analyst]

Simply white out the bottom black thing, then threshold to find dark stuff, then get the centroid in pixels, Then convert pixels to mm and divide by the frame time. If you still have questions then see my Image Segmentation Tutorial http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862 If you still have questions after adapting my tutorial to your images, then post in a brand new question.

Answer 2

[Image Analyst]

Seems like maybe you got stuck. So see the attached file.