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Mastering OpenCV 4 with Python

You're reading from  Mastering OpenCV 4 with Python

Product type Book
Published in Mar 2019
Publisher Packt
ISBN-13 9781789344912
Pages 532 pages
Edition 1st Edition
Languages
Author (1):
Alberto Fernández Villán Alberto Fernández Villán
Profile icon Alberto Fernández Villán

Table of Contents (20) Chapters

Preface Section 1: Introduction to OpenCV 4 and Python
Setting Up OpenCV Image Basics in OpenCV Handling Files and Images Constructing Basic Shapes in OpenCV Section 2: Image Processing in OpenCV
Image Processing Techniques Constructing and Building Histograms Thresholding Techniques Contour Detection, Filtering, and Drawing Augmented Reality Section 3: Machine Learning and Deep Learning in OpenCV
Machine Learning with OpenCV Face Detection, Tracking, and Recognition Introduction to Deep Learning Section 4: Mobile and Web Computer Vision
Mobile and Web Computer Vision with Python and OpenCV Assessments Other Books You May Enjoy

An introduction to contours

Contours can be seen as a curve joining all the points along the boundary of a certain shape. As they define the boundary of the shape, an analysis of these points can reveal key information for shape analysis and object detection and recognition. OpenCV provides many functions to properly detect and process contours. However, before diving into these functions, we are going to see the structure of a sample contour. For example, the following function simulates detecting a contour in a hypothetical image:

def get_one_contour():
"""Returns a 'fixed' contour"""

cnts = [np.array(
[[[600, 320]], [[563, 460]], [[460, 562]], [[320, 600]], [[180, 563]], [[78, 460]], [[40, 320]], [[77, 180]], [[179, 78]], [[319, 40]], [[459, 77]], [[562, 179]]], dtype=np.int32)]
return cnts

As you can see, a contour is an array composed...

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