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File - Create Filter

This command displays a dialog box showing the pre-programmed filters of CTSim. This command will create a 2-dimensional image of the selected filter. The center of the filter is at the center of the image.

These filters can be created in their natural frequency domain or in their inverse spatial domain.

Filter Selects the filter to generate. The available filters are:

  • |w| Bandlimit
  • |w| Hamming
  • |w| Hanning
  • |w| Cosine
  • |w| Sinc
  • Shepp
  • Bandlimit
  • Sinc
  • Hamming
  • Hanning
  • Cosine
  • Triangle
Domain Selects either the Frequency or Spatial domain. The filters have the frequency domain as their natural domain. The spatial domain is obtained either analytically or performing an inverse Fourier transformation.
X Size Number of columns in the output image.
Y Size Number of rows in the output image.
Hamming Parameter This parameter adjusts the smoothing of the Hamming filter and can range from 0 to 1. At a setting of 1, the Hamming filter is the same as the bandlimit filter. At a setting of 0.54, the Hamming filter is the same as the Hanning window.
Bandwidth Sets the bandwidth of the filter.

Axis (input) Scale Sets the scale for the filter input. By default, the input to the filter is the distance in pixels from the center of the image. By changing this value, one can set a scale the input to the filter. For example, if the output image is 101 by 101 pixels and thus the center of the image is at (50,50), then a pixel lying at point 100,50 would be 50 units from the center of the filter. By applying an Axis scale of 0.1, then that point would be scaled to 5 units from the center of the filter.
Filter (output) Scale Multiplies the output of the filter by this amount. By default, the filter has a maximum value of 1.