### Chapter 8: Frequency Domain

## SpectrumViewer

The `SpectrumViewer` application displays an input image and the logarithmically-scaled spectrum of that image. Radiobuttons are provided to allow the view to be toggled between a shifted and unshifted spectrum. An information panel displays horizontal and vertical spatial frequency, magnitude and phase for the point under the cursor, when the cursor is positioned over the spectrum.

The file `SpectrumViewer.java` compiles to produce

      SpectrumViewer.class
      SpectrumViewer$1.class
      SpectrumViewer$Buttons.class
      SpectrumViewer$Info.class
      SpectrumViewer$Scroller.class

These `.class` files have been packaged as a single JAR file, `SpectrumViewer.jar`. You can install the application by copying this JAR file, along with either the MS-DOS batch file `SpectrumViewer.bat` or the bash shell script `SpectrumViewer.sh`, as appropriate. The batch file or script should be edited to reflect the new location of the JAR file.