Gray Image Enhancement Using the Regional Similarity T. F.

It is called the Regional Similarity Transfer Function (RSTF) that considers the density distribution similarity between adjoining pixels.

This study proposes a transformation function based on the similarity of the distribution of intensity
between adjoining pixels and the maximum grey level from the histogram curve. The maximum
grey level value is labelled Max, and the contrast increases as pixels to the left approach a 0 value
while pixels to the right approach a value of 255. In addition, contrast and brightness increase
positively according to the degree of similarity of intensity distribution between adjoining pixels.