Which all the different methods available to find center of an object in an image?

Hi, Pls let me know different methods available to find center of an object in an image. Thanks in advance Rakshi

Answer 1

[Image Analyst]

regionprops() will return the center of a blob based on just its coordinates as 'Centroid'. It will also return the center of mass which is like the centroid but weighted by the intensity of each pixel in the blob. For that, ask regionprops() for 'WeightedCentroid'.

[Rakshitha]

Thanks a lot for such a quick reply :) Is this the only method or is there any other method to find the center?I need to know the different methods available as well.

[Image Analyst]

You could do it manually using the regular formulas instead of using regionprops:

meanx = mean(x(:));
meanxWeighted = sum(x(:) .* grayImage(:)) / sum(grayImage(:));

[Rakshitha]

Thank you!! Am new to Image processing can you please explain what is 'x' and what actually is being calculated in above program!!or please provide a link where i can read and understand above concept.

[Image Analyst]

x is either the x, or column, coordinates, or y, the row, coordinates.

[Rakshitha]

Thanks a lot :) What is the limitation of this method? like the shape of the object on which it can be applied n image quality etc!!

[Image Analyst]

It's a general formula. No limitation. Of course there may be a slight deviation from the "true" mean due to spatial quanitization.