In previous chapters we discussed image filters. The filter enhances the quality of image so that important details can be visualized and quantified. In this chapter, we discuss a few more image enhancement techniques. These techniques transform the pixel values in the input image to a new value in the output image using a mapping function. We discuss logarithmic transformation, power law transformation, image inverse, histogram equalization, and contrast stretching. For more information on image enhancement refer to ,,.
A transformation is a function that maps set of inputs to set of outputs so that each input has has exactly one output. For example, T(x) = x