OpenCV 3 Computer Vision with Python Cookbook

How to do it...

You need to complete the following steps:

1. Import the modules we need:

import cv2import numpy as np

2. Define a function that applies PCA to contour points and determines the new basis:

def contours_pca(contours):    # join all contours points into the single matrix and remove unit dimensions     cnt_pts = np.vstack(contours).squeeze().astype(np.float32)    mean, eigvec = cv2.PCACompute(cnt_pts, None)    center = mean.squeeze().astype(np.int32)    delta = (150*eigvec).astype(np.int32)    return center, delta

3. Define a function that displays the results of applying PCA to points of contours:

def draw_pca_results(image, contours, center, delta):    cv2.drawContours(image, contours, -1, (255, 255, 0)) cv2.line(image, tuple((center + delta[0])), ...