Hands-On Image Processing with Python

Point-wise intensity transformations – pixel transformation

As discussed in the Chapter 1, Getting Started with Image Processing, the point-wise intensity transformation operation applies a transfer function, T, to each pixel, f(x,y), of the input image to generate a corresponding pixel in the output image. The transformation can be expressed as g(x,y) = T(f(x,y)) or, equivalently, s = T(r), where r is the gray-level of a pixel in the input image and s is the transformed gray-level of the same pixel in the output image. It's a memory-less operation, and the output intensity at the location,(x, y), depends only on the input intensity at the same point. Pixels of the same intensity get the same transformation. This does not bring in new information ...