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OpenCV Essentials

You're reading from   OpenCV Essentials Acquire, process, and analyze visual content to build full-fledged imaging applications using OpenCV

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Product type Paperback
Published in Aug 2014
Publisher
ISBN-13 9781783984244
Length 214 pages
Edition 1st Edition
Tools
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Toc

Table of Contents (10) Chapters Close

Preface 1. Getting Started FREE CHAPTER 2. Something We Look At – Graphical User Interfaces 3. First Things First – Image Processing 4. What's in the Image? Segmentation 5. Focusing on the Interesting 2D Features 6. Where's Wally? Object Detection 7. What Is He Doing? Motion 8. Advanced Topics Index

Thresholding

Thresholding is one of the simplest yet most useful segmentation operations. We can safely say that you will end up using some sort of thresholding in almost any image-processing application. We consider it a segmentation operation since it partitions an image into two regions, typically, an object and its background. In OpenCV, thresholding is performed with the function double threshold(InputArray src, OutputArray dst, double thresh, double maxval, int type).

The first two parameters are the input and output images, respectively. The third input parameter is the threshold chosen. The meaning of maxval is controlled by the type of thresholding we want to perform. The following table shows the operation performed for each type:

Type

dst(x,y)

THRESH_BINARY

maxval if src(x,y) is greater than thresh and 0 if otherwise

THRESH_BINARY_INV

0 if src(x,y) is greater than thresh and maxval if otherwise

THRESH_TRUNC

thresh if src(x,y) is greater than thresh and src(x,y...

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