IDL Demo Library

Fourier Filtering

This example demonstrates some of the filtering capabilities of IDL using Fourier transformations.

The original image is shown at the left of the display. The image at the right is displayed as selected by the droplist located below the image. The original data is processed according to the filter options shown to the left of the images.

Menu Options

File Menu

Open...

You can choose from among 16 different sets of data from disciplines including astronomy, geology, and medicine.

Quit

Quit the Fourier Filtering Demo and return to the IDL Demo main screen.

Edit Menu

Select "Color Palette" to launch the XLOADCT application. You can select different color tables to help clarify the various images.

Help Menu

Select "About Fourier filtering" for information about the Fourier Filtering demo.

Filter Options

Function droplist

Select between 3 filter functions: Butterworth, Exponential, and Ideal.

Order droplist

Select a filter order between 1 and 6.

Type droplist

Select the filter type: Low pass, High pass, Band pass, or Band reject.

Frequency Cutoff slider

Select the frequency cutoff of the filter.

Bandwidth slider

Select the frequency bandwidth of the filter. This option is only enabled when the filter type is set to Band pass or Band reject.

Plot View Options

The droplist located under the display to the right consists of the following options:

Filter intensity image, Filter cross section, and Shaded surface of a filter are enabled only when viewing an image data set.

  IDL Demo Online Help (October 11, 2006)