'Declaration
 
Public Shared Sub LowPassFilter( _
   ByVal page As ImGearRasterPage, _
   ByVal filterBrand As ImGearFreqIPFilterBrands, _
   ByVal cutoffFrequency As Double, _
   ByVal filterOrder As Integer, _
   ByVal rippleFactor As Double _
) 

'Usage
 
Dim page As ImGearRasterPage
Dim filterBrand As ImGearFreqIPFilterBrands
Dim cutoffFrequency As Double
Dim filterOrder As Integer
Dim rippleFactor As Double
 
ImGearFrequencyProcessing.LowPassFilter(page, filterBrand, cutoffFrequency, filterOrder, rippleFactor)

public static void LowPassFilter( 
   ImGearRasterPage page,
   ImGearFreqIPFilterBrands filterBrand,
   double cutoffFrequency,
   int filterOrder,
   double rippleFactor
)

public: static void LowPassFilter( 
   ImGearRasterPage* page,
   ImGearFreqIPFilterBrands filterBrand,
   double cutoffFrequency,
   int filterOrder,
   double rippleFactor
) 

public:
static void LowPassFilter( 
   ImGearRasterPage^ page,
   ImGearFreqIPFilterBrands filterBrand,
   double cutoffFrequency,
   int filterOrder,
   double rippleFactor
) 

Parameters

page

ImageGear.Core.ImGearRasterPage class object to be processed.

filterBrand

Brand of the filter to use. Constants are listed in ImGearFreqIPFilterBrands enumeration.

cutoffFrequency

Cutoff frequency for the low-pass filter.

filterOrder

Filter order to use, applicable to all except Ideal filter.

rippleFactor

A factor which determines the pass-band ripple for Chebyshev filters, with value between [0, 1].

Parameter filterBrand specifies the brand of filter to use, with available brands being Ideal, Butterworth, Gaussian, Chebyshev I, and Chebyshev II.

Parameter cutoffFrequency specifies the cutoff frequency for the low-pass filter. This parameter should have value within the range of [0, 1], where 0 is DC and 1 is the Nyquist frequency.

Before using this method, like other frequency processing methods, InitializeFFTW method must be called first to initialize the support for FFTW.

Can be applied only to 8bit grayscale images with one channel.

ImGearFrequencyProcessingVerifier.CanApplyLowPassFilter method can be called to check whether the operation can be performed or not.

Reference