Figure 3.2. Aliasing in digital image.

Both images were down-sampled from a higher resolution. To make the effect more visible, an enlarged portion is shown. A proper digital filter was used for the upper image and it does not show aliasing. In the lower image no filtering was applied producing an edgy structure in the diagonal lines. Aliasing can also increase the noise or grain in an image as shown in the enlarged face.

In scanning, the original film image would represent the higher resolution image that is sampled at a lower rate. Without filtering similar effects could occur.