Truncation of ellipse major and minor axis lengths

[tobbelobb]

In an earlier issue, I've said that I solved an issue by adding + 1.0 to these lines:

  // semimajor axis
  a = sqrt(F3 / A2) + 1.0;
  // semiminor axis
  b = sqrt(F3 / C2) + 1.0;

Now I've removed the + 1.0s again, and solved the issue in a better way.

The semi-major and semi-minor axis lengths were truncated, which caused the accuracy issue I had. This is solved by changing the type of the axes member within the mEllipse class from cv::Size to cv::Size2d.

Here: https://github.com/CihanTopal/ED_Lib/blob/master/EDCircles.h#L54

Also, the constructor and all calls to it must be adjusted to take doubles.

All other parts of the code use doubles for major/minor axis lengths, so no further changes are required.

This fix improves accuracy of the ellipse detector by half, or maybe a quarter of, a pixel on average.