title: How Convexity Defect is calculated in OpenCV?
body: <p>What is the algorithm used in OpenCV function <a href="https://docs.opencv.org/3.4.3/d3/dc0/group__imgproc__shape.html#gada4437098113fd8683c932e0567f47ba" rel="nofollow noreferrer"><code>convexityDefects()</code></a> to calculate the convexity defects of a contour?</p>
  
  <p>Please, describe and illustrate the high-level operation of the algorithm, along with its inputs and outputs.</p>