How to get Active Contour

A summary of the video tutorial Active Contour | Boundary Detection.

1. Draw a circle around the image (roughly around the object). This is the initial contour.

2. Calculate the gradient of the image.

3. Blur the gradient values in the images so that the value spread to other part of the image, creating a slope to guide a point to the position with large gradient value.

4. Apply greedy search from the contour to move control point to the points with large gradient values.

5. It is almost done, but the contour is not smooth. A modification to this solution could be to adjust the gradient value with smoothness and elasticity of the contour. The two values are defined as the derivative and second derivative on the contour.