Digital image processing remains a challenging domain of programming for several reasons. First the issue of digital image processing appeared relatively late in computer history, it had to wait for the arrival of the first graphical operating systems to become a true matter. Secondly, digital image processing requires the most careful optimisations and especially for real time applications. Comparing image processing and audio processing is a good way to fix ideas.Finally, digital image processing is by definition a two dimensions domain; this somehow complicates things when elaborating digital filters.