Checking whether two point are on same object

Hello guys,

I need your help in solving the following problem:

Given A binary image and two points p1,p2 on objects (object is a patch of 0's) and assume that the shape of there objects are polygons, check if p1 and p1 lies on the same object.

Thanks in advance.

Answer 1

[Image Analyst]

I'll assume you have a binary image called binaryImage, that uses a non standard definition of objects being black (0), and I'll assume you have two points p1 and p2 defined by coordinates (row1, col1), and (row2, col2). First you need to invert your image so that you have a standard image where the objects are white/true/1 and the background is black/false/0.

binaryImage = ~binaryImage;

Then you need to label the image so that each connected component will have it's own label ID number

labeledImage = bwlabel(binaryImage);

Now, to see if the two points are in the same region, simply get the value from the labeled image and compare them for equality

if labeledImage(row1, col1) == labeledImage(row2, col2)
    % Point 1 and point 2 are in the same region.
else
    % Point 1 and point 2 are in the different regions.
end