Book Image

Hands-On Image Processing with Python

By : Sandipan Dey
Book Image

Hands-On Image Processing with Python

By: Sandipan Dey

Overview of this book

Image processing plays an important role in our daily lives with various applications such as in social media (face detection), medical imaging (X-ray, CT-scan), security (fingerprint recognition) to robotics & space. This book will touch the core of image processing, from concepts to code using Python. The book will start from the classical image processing techniques and explore the evolution of image processing algorithms up to the recent advances in image processing or computer vision with deep learning. We will learn how to use image processing libraries such as PIL, scikit-mage, and scipy ndimage in Python. This book will enable us to write code snippets in Python 3 and quickly implement complex image processing algorithms such as image enhancement, filtering, segmentation, object detection, and classification. We will be able to use machine learning models using the scikit-learn library and later explore deep CNN, such as VGG-19 with Keras, and we will also use an end-to-end deep learning model called YOLO for object detection. We will also cover a few advanced problems, such as image inpainting, gradient blending, variational denoising, seam carving, quilting, and morphing. By the end of this book, we will have learned to implement various algorithms for efficient image processing.
Table of Contents (20 chapters)
Title Page
Copyright and Credits
Dedication
About Packt
Contributors
Preface
Index

Histogram processing – histogram equalization and matching


Histogram processing techniques provide a better method for altering the dynamic range of pixel values in an image so that its intensity histogram has a desired shape. As we have seen, image enhancement by the contrast stretching operation is limited in the sense that it can apply only linear scaling functions.

 

 

Histogram processing techniques can be more powerful by employing non-linear (and non-monotonic) transfer functions to map the input pixel intensities to the output pixel intensities. In this section, we shall demonstrate the implementation of a couple of such techniques, namely histogram equalization and histogram matching, using the scikit-image library's exposure module.

Contrast stretching and histogram equalization with scikit-image

Histogram equalization uses a monotonic and a non-linear mapping which reassigns the pixel intensity values in the input image in such a way that the output image has a uniform distribution...