Mastering OpenCV 4 with Python

Chapter 8

1. The cv2.findContours() function finds contours in a binary image (for example, the resulting image after a thresholding operation).
2. The four flags OpenCV provides for compressing contours are as follows:

• cv2.CHAIN_APPROX_NONE
• cv2.CHAIN_APPROX_SIMPLE
• cv2.CHAIN_APPROX_TC89_KCOS
• cv2.CHAIN_APPROX_TC89_L1

3. The cv2.moments() function calculates all of the moments up to the third order of a polygon or rasterized shape.
4. The moment, m00, gives the area of the contour.
5. OpenCV provides the cv2.HuMoments() function to calculate the seven Hu moment invariants.
6. The cv2.approxPolyDP() function returns a contour approximation of the given contour based on the given precision. This function uses the Douglas-Peucker algorithm. The epsilon parameter ...