Opencv simplify contour

1. How do you approximate contour?
2. What is cv2 contourArea?
3. How do you draw specific contours in OpenCV Python?

How do you approximate contour?

In order to calculate contour approximation, first we need to compute the actual perimeter of the contoured region. And once we have the length of the perimeter, we can use it to approximate it by making a call to cv2. approxPolyDP function.

What is cv2 contourArea?

The extent of an object is computed as the ratio of contour area to its bounding rectangle area. So, to compute the extent, we first have to find the contour area and bounding rectangle area. The contour area of an object can be found using cv2. contourArea() function.

How do you draw specific contours in OpenCV Python?

To draw the contours, cv. drawContours function is used. It can also be used to draw any shape provided you have its boundary points. Its first argument is source image, second argument is the contours which should be passed as a Python list, third argument is index of contours (useful when drawing individual contour.