OpenCV 3 Computer Vision with Python Cookbook

How to do it...

Perform the following steps:

1. Import the modules:

import cv2import numpy as np

2. Load image and define mouse callback function for selecting image ROI. What is inside of the rectangle that is drawn will be our template for matching:

img = cv2.imread('../data/Lena.png', cv2.IMREAD_COLOR)show_img = np.copy(img)mouse_pressed = Falsey = x = w = h = 0def mouse_callback(event, _x, _y, flags, param):    global show_img, x, y, w, h, mouse_pressed    if event == cv2.EVENT_LBUTTONDOWN:        mouse_pressed = True        x, y = _x, _y        show_img = np.copy(img)    elif event == cv2.EVENT_MOUSEMOVE:        if mouse_pressed:            show_img = np.copy(img)            cv2.rectangle(show_img, (x, y),                          (_x, _y), (0, 255, 0), 2)    elif event == cv2.EVENT_LBUTTONUP:        mouse_pressed = False w, h ...