Analogous to the low-pass case, increasing the order causes the transition between the passband and stopband to become more sharp. This section shows the result of smoothing a binary image with the different filters discussed in the previous section. The input image for all cases is shown in figure 20 . The results appeared as expected. It is probable that all of the filters are ringing in this exercise, just that its effects are only noticeable in the most extreme cases.
Windowing functions transform ideal filters which have infinite length to filters of finite length.