Author: datahacker.rs

OpenCV #014 Histogram Equalization

Digital Image Processing using OpenCV (Python & C++) Highlights: In this post, we will learn what an image histogram is and why it is useful. We will also learn about how histogram equalization works and to get practical how to implement it from scratch. Let’s roll. What is a Histogram? Histogram Equalization How does it work? Implementation from scratch 1. What is a histogram? When we think of a histogram, we can interpret it as…
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OpenCV #013 Harris Corner Detector – Experiment

Highlights: In this post we will continue working on Harris Corner Detector. In the previous post we presented the basic idea behind this algorithm, and here we will wrap this up and show how this method works in OpenCV. Tutorial Overview: Interpreting the Second Moment Matrix Interpreting the Eigenvalues Harris Corner Response Function Harris Detector Algorithm Code 1. Interpreting the Second Moment Matrix Let’s first consider the case, where the gradient at every point in…
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OpenCV #007 Thresholding

Digital Image Processing using OpenCV (Python & C++) Highlights: In this post we will learn about Thresholding. This method is essential in many computer vision applications. The purpose of this post is to show and benchmark performance of several different approaches, and also to provide you with the necessary knowledge to implement it. Tutorial Overview: Thresholding Simple thresholding Adaptive thresholding Otsu’s Binarization 1. Thresholding In the last post we explained why edges are important for…
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OpenCV #011 Discrete Fourier Transform, Part 1

Digital Image Processing using OpenCV (Python & C++) Highlights: In this post, we will learn about why the Fourier transform is so important. We will also explain some fundamental properties of Fourier transform. Also, we will discuss the advantages of using frequency-domain versus time-domain representations of a signal. Finally, uses cases will be shown where it may be applied. In Mathematics, we often use the Fourier Transform. You take a hard problem, convert it to…
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OpenCV #012 Discrete Fourier Transform, Part 2

Highlights: In the previous post,  we learnt some fundamental details about the Fourier transform and why it’s worth learning. We also showed how to transform an image into its frequency domain. I recommend you read about it here if you haven’t. In this section, we would focus on filtering in the frequency domain. We would see the effects of applying a low and high pass filter. Almost all natural images have similar power spectrum Tutorial…
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