how to detect shapes in an image?

Question

I want to detect a circle, rectangle shaped object in an image and read the information from that object. Is there any api in java which will be helpful to me?

Ex: D

Answer 1

Circles are perfect targets for the Hough transform. Check this out Detect circles with HT and OpenCV

Rectangles are a bit harder since the Hough Transform is not rotation invariant. You can go into edge detection and fast fitting (Fast line and rectangle detection by clustering and grouping)

Answer 2

Here's an answer to a similar question for C++.

For Java, you can use the OpenCV wrappers. However, once you understand the essence of the approach you should be able to solve your problem using whichever framework is available.