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OpenCV 4 with Python Blueprints

You're reading from   OpenCV 4 with Python Blueprints Build creative computer vision projects with the latest version of OpenCV 4 and Python 3

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Product type Paperback
Published in Mar 2020
Publisher Packt
ISBN-13 9781789801811
Length 366 pages
Edition 2nd Edition
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Authors (4):
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Michael Beyeler (USD) Michael Beyeler (USD)
Author Profile Icon Michael Beyeler (USD)
Michael Beyeler (USD)
Dr. Menua Gevorgyan Dr. Menua Gevorgyan
Author Profile Icon Dr. Menua Gevorgyan
Dr. Menua Gevorgyan
Michael Beyeler Michael Beyeler
Author Profile Icon Michael Beyeler
Michael Beyeler
Arsen Mamikonyan Arsen Mamikonyan
Author Profile Icon Arsen Mamikonyan
Arsen Mamikonyan
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Table of Contents (14) Chapters Close

Preface 1. Fun with Filters 2. Hand Gesture Recognition Using a Kinect Depth Sensor FREE CHAPTER 3. Finding Objects via Feature Matching and Perspective Transforms 4. 3D Scene Reconstruction Using Structure from Motion 5. Using Computational Photography with OpenCV 6. Tracking Visually Salient Objects 7. Learning to Recognize Traffic Signs 8. Learning to Recognize Facial Emotions 9. Learning to Classify and Localize Objects 10. Learning to Detect and Track Objects 11. Profiling and Accelerating Your Apps 12. Setting Up a Docker Container 13. Other Books You May Enjoy

Understanding the process flow

Features are extracted, matched, and tracked by the FeatureMatching class—especially by the public match method. However, before we can begin analyzing the incoming video stream, we have some homework to do. It might not be clear right away what some of these things mean (especially for SURF and FLANN), but we will discuss these steps in detail in the following sections.

For now, we only have to worry about initialization:

class FeatureMatching: 
     def __init__(self, train_image: str = "train.png") -> None:

The following steps cover the initialization process:

  1. The following line sets up a SURF detector, which we will use for detecting and extracting features from images (see the Learning feature extraction section for further details), with a Hessian threshold between 300 and 500, that is, 400:
self.f_extractor = cv.xfeatures2d_SURF...
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