I am currently working on very similar project.

Using OpenCV i feel is easier than using MATLAB. If u know C# then EMGU is the best wrapper over OpenCV to use for your purpose. EMGU supports Windows, Linux as well as Android.

Algorithm:

0. Assuming u have a binary image without noise. For now assuming the attached image all black blobs. Image should be of single channel.

1. Do a image.Not() for getting negative of the image so that u'll be having white pixels in place of black and black in place of white.

2. Do image.smooth(3)

3. do contour = image.FindContour(...);

4. for finding any kind of circle or ellipse fit the contour in ellipse function. Iff contour is having at least 5 points. And also keep the area threshold.

5. for finding any kind of square, rectangle or rhombus etc look for contour having points equal to 4. And also keep the area threshold.U can also determine the adjacent angles of the sides to be sure.

6. for finding any kind of triangle etc look for coU can also determine the adjacent angles of the sides to be sure.ntour having points equal to 3. And also keep the area threshold.

7. At last use draw functions to draw in an empty black image using the filtered contours. Then using flood fill function fill the shapes with different colors also.

Another way is here : http://www.emgu.com/wiki/index.php/Shape_(Triangle,_Rectangle,_Circle,_Line)_Detection_in_CSharp

For given problem statement no neural network is needed from user's perspective.

This algo covers all the requirement u asked for. I can make complete algorithm also in C# if u r not satisfied. \m/

I will try to do this using your method and the example method from the EMGU site. It satisfies me but i'd be really pleased if You make complete algorithm .

I've been working on it but i still get problem with detecting a rectangle and triangle shapes. Theres no problem with finding circles using Hough Circle Transform. Im using OpenCV.

OK I'll need some time to make an application for the purpose. Is a week time ok? By that time u wud make it for sure.

Thanks for giving me advices. If you are able to to that it will be great. Soon, i'll send You my experimental algorithm in C++ where i can recognize rectangles, triangles and circles.

Check this cSharp file .. please know about EMGU and c# . Start with the software environment setup. Or work on getting equivalent c++ functions of OpenCV. Happy coding.

I tried this in here. Please work with floodFill . :)

That's my result.

Congrats \m/

To fill u can use => image.Draw(contour, new Gray(100), -1);

Just for info: http://docs.opencv.org/doc/tutorials/imgproc/table_of_content_imgproc/table_of_content_imgproc.html#table-of-content-imgproc