K Filter

Description Apply spatial anti-aliasing filter to volume before downsampling.
Module(s) Gather Attributes
Requirements Volume
Related Header and Trace Interpolation
Works with Gathers

K Filter is a spatial anti-aliasing filter for use prior to spatial downsampling (with Header and Trace Interpolation). It applies a mute in F-K space, muting K values larger than the new Nyquist following downsampling, with an adjustable taper.

Best practice is to spatially de-alias the data  using F-X interpolation  (with Header and Trace Interpolation) prior to K filtering and downsampling.

  1. In the Control Panel, open the Process tab.
  2. At the tab header, click the Add icon and select New Process.
  3. Scroll down and double-click on K Filter.
  4. Type a name for the process and click OK.

Configuring K Filter

Smooth a 2D/3D volume
  1. Volume: Select the input volume.
  2. Stop Wavenumber (as a percentage of spatial Nyquist): Lowers the amplitude of high wavenumbers. At the specified percentage of spatial Nyquist, only 5% of the amplitude is passed through. This process acts similarly to the "stop frequency" of time-based low-pass filters.
  3. Filter Shape: Controls the shape of the filter with the following options:
    • Blackman-Harris: Activates the Taper Width (as a percent of spatial Nyquist) parameter, which controls the width of the taper as a percentage of the downsampled K range. For instance, if the downsampled K range is [-1000, 1000] then a taper of 15% will taper in the ranges [-1000, -850] and [850, 1000].
    • Butterworth: Activates the Butterworth Slope (dB/octave) parameter, which is the slope in decibels per octave of the Butterworth filter to use.
    • Bessel: Activates the Bessel Order parameter, which determines the order of the Bessel filter to use (that is, the degree of the modified Bessel polynomial that determines the filter).
  4. Output type: "Filtered Output" or "Removed Noise".