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OpenCV with Python Blueprints

OpenCV with Python Blueprints

By : Michael Beyeler, Michael Beyeler (USD)
4.4 (10)
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OpenCV with Python Blueprints

OpenCV with Python Blueprints

4.4 (10)
By: Michael Beyeler, Michael Beyeler (USD)

Overview of this book

Design and develop advanced computer vision projects using OpenCV with Python About This Book Program advanced computer vision applications in Python using different features of the OpenCV library Practical end-to-end project covering an important computer vision problem All projects in the book include a step-by-step guide to create computer vision applications Who This Book Is For This book is for intermediate users of OpenCV who aim to master their skills by developing advanced practical applications. Readers are expected to be familiar with OpenCV’s concepts and Python libraries. Basic knowledge of Python programming is expected and assumed. What You Will Learn Generate real-time visual effects using different filters and image manipulation techniques such as dodging and burning Recognize hand gestures in real time and perform hand-shape analysis based on the output of a Microsoft Kinect sensor Learn feature extraction and feature matching for tracking arbitrary objects of interest Reconstruct a 3D real-world scene from 2D camera motion and common camera reprojection techniques Track visually salient objects by searching for and focusing on important regions of an image Detect faces using a cascade classifier and recognize emotional expressions in human faces using multi-layer peceptrons (MLPs) Recognize street signs using a multi-class adaptation of support vector machines (SVMs) Strengthen your OpenCV2 skills and learn how to use new OpenCV3 features In Detail OpenCV is a native cross platform C++ Library for computer vision, machine learning, and image processing. It is increasingly being adopted in Python for development. OpenCV has C++/C, Python, and Java interfaces with support for Windows, Linux, Mac, iOS, and Android. Developers using OpenCV build applications to process visual data; this can include live streaming data from a device like a camera, such as photographs or videos. OpenCV offers extensive libraries with over 500 functions This book demonstrates how to develop a series of intermediate to advanced projects using OpenCV and Python, rather than teaching the core concepts of OpenCV in theoretical lessons. Instead, the working projects developed in this book teach the reader how to apply their theoretical knowledge to topics such as image manipulation, augmented reality, object tracking, 3D scene reconstruction, statistical learning, and object categorization. By the end of this book, readers will be OpenCV experts whose newly gained experience allows them to develop their own advanced computer vision applications. Style and approach This book covers independent hands-on projects that teach important computer vision concepts like image processing and machine learning for OpenCV with multiple examples.
Table of Contents (9 chapters)
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8
Index

Chapter 1. Fun with Filters

The goal of this chapter is to develop a number of image processing filters and apply them to the video stream of a webcam in real time. These filters will rely on various OpenCV functions to manipulate matrices through splitting, merging, arithmetic operations, and applying lookup tables for complex functions.

The three effects are as follows:

  • Black-and-white pencil sketch: To create this effect, we will make use of two image blending techniques, known as dodging and burning
  • Warming/cooling filters: To create these effects, we will implement our own curve filters using a lookup table
  • Cartoonizer: To create this effect, we will combine a bilateral filter, a median filter, and adaptive thresholding

OpenCV is such an advanced toolchain that often the question is not how to implement something from scratch, but rather which pre-canned implementation to choose for your needs. Generating complex effects is not hard if you have a lot of computing resources to spare. The challenge usually lies in finding an approach that not only gets the job done, but also gets it done in time.

Instead of teaching the basic concepts of image manipulation through theoretical lessons, we will take a practical approach and develop a single end-to-end app that integrates a number of image filtering techniques. We will apply our theoretical knowledge to arrive at a solution that not only works but also speeds up seemingly complex effects so that a laptop can produce them in real time.

The following screenshot shows the final outcome of the three effects running on a laptop:

Fun with Filters

Note

All of the code in this book is targeted for OpenCV 2.4.9 and has been tested on Ubuntu 14.04. Throughout this book, we will make extensive use of the NumPy package (http://www.numpy.org). In addition, this chapter requires the UnivariateSpline module of the SciPy package (http://www.scipy.org) as well as the wxPython 2.8 graphical user interface (http://www.wxpython.org/download.php) for cross-platform GUI applications. We will try to avoid further dependencies wherever possible.

Visually different images
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OpenCV with Python Blueprints
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