applies a lowpass filter with a cutoff frequency ωc to an array of data.

uses a filter kernel of length n.

applies a smoothing window wfun to the filter kernel.

applies a lowpass filter to image.

applies a lowpass filter to audio.

Details and OptionsDetails and Options

  • LowpassFilter works with arbitrary-rank numerical arrays, regular and irregular time series, 2D and 3D images, and sampled sound objects, operating separately on each channel.
  • When applied to images and multidimensional arrays, filtering is applied successively to each dimension, starting at level 1. LowpassFilter[data,{ωc1,ωc2,}] uses the frequency ωci for the ^(th) dimension.
  • LowpassFilter[data,ωc] uses a filter kernel length and smoothing window suitable for the cutoff frequency ωc and the input data.
  • Typical smoothing windows wfun include:
  • BlackmanWindowsmoothing with a Blackman window
    DirichletWindowno smoothing
    HammingWindowsmoothing with a Hamming window
    {v1,v2,}use a window with values vi
    fcreate a window by sampling f between and
  • LowpassFilter works with numeric lists as well as Audio and Sound objects.
  • The following options can be given:
  • Padding"Fixed"the padding value to use
    SampleRateAutomaticsample rate assumed for the input
  • By default, SampleRate->1 is assumed for images as well as data. For audio signals of sample rate r, SampleRate->r is used.
  • With SampleRate->r, the cutoff frequency ωc should be between 0 and . »

ExamplesExamplesopen allclose all

Basic Examples  (3)Basic Examples  (3)

Lowpass filtering of a noisy square wave:

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Lowpass filtering of audio:

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Lowpass filtering of an image:

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Introduced in 2012
| Updated in 2015