Chapter 4. Image Enhancement

In this chapter, we will discuss some of the most basic tools in image processing, such as mean/median filtering and histogram equalization, which are still among the most powerful tools. The objective of image enhancement is to improve the quality of an image or make particular features appear more prominent. These techniques are more general purpose techniques, and a strong model of the degradation process is not assumed (unlike image restoration). Some examples of image enhancement techniques are contrast stretching, smoothing, and sharpening. We will describe the basic concepts and implementation of these techniques using Python library functions and using PIL, scikit-image, and scipy ndimage libraries. We will become familiar with simple and still-popular approaches.

We will start with point-wise intensity transformation, and then discuss contrast stretching, thresholding, half-toning, and dithering algorithms, and the corresponding Python library functions...