Book Image

Raspberry Pi Computer Vision Programming - Second Edition

By : Ashwin Pajankar
5 (1)
Book Image

Raspberry Pi Computer Vision Programming - Second Edition

5 (1)
By: Ashwin Pajankar

Overview of this book

Raspberry Pi is one of the popular single-board computers of our generation. All the major image processing and computer vision algorithms and operations can be implemented easily with OpenCV on Raspberry Pi. This updated second edition is packed with cutting-edge examples and new topics, and covers the latest versions of key technologies such as Python 3, Raspberry Pi, and OpenCV. This book will equip you with the skills required to successfully design and implement your own OpenCV, Raspberry Pi, and Python-based computer vision projects. At the start, you'll learn the basics of Python 3, and the fundamentals of single-board computers and NumPy. Next, you'll discover how to install OpenCV 4 for Python 3 on Raspberry Pi, before covering major techniques and algorithms in image processing, manipulation, and computer vision. By working through the steps in each chapter, you'll understand essential OpenCV features. Later sections will take you through creating graphical user interface (GUI) apps with GPIO and OpenCV. You'll also learn to use the new computer vision library, Mahotas, to perform various image processing operations. Finally, you'll explore the Jupyter Notebook and how to set up a Windows computer and Ubuntu for computer vision. By the end of this book, you'll be able to confidently build and deploy computer vision apps.
Table of Contents (15 chapters)

Drawing geometric shapes with OpenCV and NumPy

Let's learn how to draw various geometric shapes using the OpenCV drawing functions. We will also use NumPy here.

The following code imports all the required libraries for this demonstration:

import cv2
import numpy as np

The following code creates an RGB ndarray of all zeros. It is an image in which all the pixels are black:

image = np.zeros((200, 200, 3), np.uint8)

We are using the np.zeros() function to create an ndarray of all zero elements.

We'll start by drawing a line, as it is a simple geometric shape. With the help of the following code, we'll draw a line with coordinates (0, 199) and (199, 0), with red color [(0, 0, 255) in BGR], and with a thickness of 2 pixels:

cv2.line(image, (0, 199), (199, 0), (0, 0, 255), 2)

All the OpenCV functions for drawing have the following common parameters:

  • img: This is the image where we need to draw the geometric shapes.
  • color: This is passed...