# filterVisualize

## PURPOSE

Used to visualize a 1D/2D/3D filter.

## SYNOPSIS

function filterVisualize( f, show, arg )

## DESCRIPTION

     Used to visualize a 1D/2D/3D filter.

     For 1d filters:
      Marks local filter maxima with a green '+' and minima with a red '+'.
      Also shows the fft response of the filter.

     For 2d filters:
      Marks local filter maxima with a green '+' and minima with a red '+'.
      Also shows the fft response of the filter.  Can optionally also plot a
      scanline through either center row/column.

     For 3d filters:
      Dark lobes correspond to negative areas.  Surfaces shown are drawn at a
      percentage of the peak filter response detemined by frac.

     USAGE
      filterVisualize( f, [show], [arg] )

     INPUTS
      f         - filter to visualize
      show      - [1] figure to use for display (0->uses current)
      arg       - different meanding depending on dimension
                  d=1: [] not used
                  d=2: [''] 'row' OR 'col': display centeral row OR col line
                  d=3: [.1] frac of max value of f at which to draw surfaces

     OUTPUTS

     EXAMPLE
      f=filterBinomial1d( 10, 0 ); filterVisualize( f, 1 ); %1d
      f=filterDog2d( 15, 10, 1 ); filterVisualize( f, 2, 'row' ); %2d
      f=filterDoog([51 51 99],[3 3 5],[1 2 3],0); filterVisualize(f,4,.1); %3d

     See also FILTERGAUSS, FBVISUALIZE

     Piotr's Image&Video Toolbox      Version 2.0
     Copyright 2008 Piotr Dollar.  [pdollar-at-caltech.edu]
     Please email me if you find bugs, or have suggestions or questions!
     Licensed under the Lesser GPL [see external/lgpl.txt]

## CROSS-REFERENCE INFORMATION

This function calls:

- im Function for displaying grayscale images.

This function is called by:

- FbVisualize Used to visualize a series of 1D/2D/3D filters.
- filterBinomial1d 1D binomial filter (approximation to Gaussian filter)
- filterDog2d Difference of Gaussian (Dog) Filter.
- filterDoog n-dim difference of offset Gaussian DooG filter (Gaussian derivative).
- filterGabor1d Creates an even/odd pair of 1D Gabor filters.
- filterGabor2d Creates an even/odd pair of 2D Gabor filters.
- filterGauss n-dimensional Gaussian filter.