Fourier Filtering takes an image and calculates its frequency components, called the FFT image. Then unwanted frequency components are identified and removed from the FFT image. When the FFT image is back transformed, the resulting AFM image will not have the frequency components that were removed in the FFT image. FFT filtering is particularly effective on images with repetitive patterns.

5.1.4 Scale / Zoom / Rotation

An AFM image may have many features an operator does not want to show. These can be "removed" by zooming in on only the desired features. This is only possible if the original image has a high enough resolution that the resulting image has enough pixels. Associated with the zoom function, pixels may be mathematically added to the image with the scale function. As an example, if an image is 200 X 200 pixels and an area that is 50 X 50 pixels is used for the zoom, it is possible to increase the number of pixels in the final image from 50 X 50 to 200 X 200. Often, zooming will result in images that show a lot of pixilation.

Another process step that is sometimes required is to rotate the scan axis in an AFM image. This is necessary if it is required that features in an image line up with the scan axis. This is often required for the analysis of technical samples.

5.1.5 Error Correction

Unwanted errors sometimes occur in AFM images; for example there may be a short term unwanted vibration or a "glitch" in the image. These errors may be removed with special software for error correction. Line removal can be done by removing a single line and replacing it with the average of the two lines next to it. A "glitch" may be removed by replacing the glitched pixel with the average of the eight pixels around the unwanted pixel.

5.2 Display

A great amount of information is gleaned from an AFM image through visualization of the image. There are several ways of displaying images to make them more interesting to view. Sometimes features can be enhanced and seen more easily by changing the display parameters. Display functions do not change the AFM data or change the way the data is viewed.