Chapter 3 of text book “Digital Image Processing” Gonzales named Intensity Transformations and Spatial Filtering, which consists of 6 sub-sections including (1) Basics intensity transformation functions, (2) Histogram Processing, (3) Spatial Filtering, (4) Smoothing Spatial Filters, (5) Sharpening Spatial Filters, and (6) Using Fuzzy Techniques for Intensity Transformations and Spatial Filtering. In Basic Intensity Transformation Functions, there are 4 important functions including Image Negative, Log Transformation, Power-Law (Gamma) Transformations, and Piecewise-Linear Transformation Functions. In terms of Histogram Processing, I learned about Histogram Equalization, Histogram Matching (Specification). Local Histogram Processing and Using Histogram Statistics for Image Enhancement.