Average Dithering

Classical Algorithm - Developed Algorithms

The Average Dithering is a basic two-level algorithm for halftone image. It consists in choosing a certain constant gray level, in  particular the average value of image pixels, and using it as a global threshold in deciding whether a pixel should be quantized to 0 or to 1. All pixels whose intensity level lies above the average value (the threshold) are quantized to 1; all others get a value of 0.

This method is simple to implement but it has a disadvantage: quantization contouring is quite perceptible. 

Exemplifying: