How To: Use the Interactive Spectral Filters available in the MAGMAP extension

Objective:

I would like to use the Interactive Spectral Filters available in the MAGMAP extension. What are the steps I need to perform to prepare my data for this procedure? Once I have prepared my data, how do I use the Interactive Spectral Filter dialog?

Environment:

Oasis montaj version 7.1 with the MAGMAP extension

Resolution:

The Interactive Spectrum Filtering process enables you to display a radially averaged power spectrum of an FFT2 Transform image, a selected filter profile, and the resultant
(filtered) power spectrum profile in an interactive window. The filters can be selected from a dropdown list or from a predefined control file. Filter parameters can then be interactively modified to obtain the best results for your data.

A preview window allows you to view both your original grid and the resultant filtered grid. As the filter parameters are interactively modified, the results can immediately be
seen in the Filtered Grid window.

Before using the Interactive Spectrum Filtering process, these steps need to be performed:

• Prepare the grids for transformation (MAGMAP > Interactive Filtering > Prepare Grid)


• Apply the forward Fast Fourier Transform (MAGMAP > Interactive Filtering > Forward FFT)


• Calculate the radial average spectrum (MAGMAP > Interactive Filtering > Radial Average Spectrum)

To specify the Interactive Spectrum Filters:

1. MAGMAP menu > Interactive Filtering > Interactive Spectrum Filters.
   
2. For the Spectrum File Name parameter, select the *.SPC file that was created when calculating the radially averaged power spectrum.
   
3. Enter a new name for the Control File Name parameter.
   If you specify a control file that already contains filter definitions then the values already stored in that file will be loaded as default settings in the dialog. If you want to run several tests with the Interactive Spectrum Filters, it is recommended that you give a different name for each control file. If you use the default Control File Name, it will get overwritten with each subsequent test.
   
4. Select a filter from the Filter Name list.
   Up to four consecutive filters can be applied. You have 10 pre-build filters to choose from.
   
5. Click Preview to see an interactive view of both the Original Grid and the Filtered Grid.
   You can zoom into a specific area and then zoom out to full extent again.
   
6. Click OK on the Interactive Spectrum Filter dialog when you are satisfied with the filters you would like to apply.

As of version 7.1, in the Interactive Spectral Filter dialog the graph of the power spectrum has wavelength instead of wavenumber along the X-axis.

To apply filters and inverse FFT:

1. MAGMAP menu > Interactive Filtering > Apply Filter
   
2. Specify a name for the Name of Output Grid File.
   
3. See the Help for the differences between clicking OK, Flt-Inv Only or Filter Only.