FrequencyFilterCommand Class

Summary

Filters the frequency harmonics data produced by a Fourier Transform method using a range rectangle.

Syntax

C++

public class FrequencyFilterCommand

Public Class FrequencyFilterCommand

public ref class FrequencyFilterCommand

Remarks

This command is used only when working with Fourier Transform methods.
This command does not support 12 and 16-bit grayscale and 48 and 64-bit color images. If the image is 12 and 16-bit grayscale and 48 and 64-bit color, the command will not threw an exception.
This command does not support signed images.

For more information, refer to Removing Noise.

Example

Run the FrequencyFilterCommand on an image.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
 
public void FrequencyFilterCommandExample() 
{ 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, @"ImageProcessingDemo\FourierTransform.jpg")); 
 
   // Prepare the command 
   // Resize the image to make sure the image's dimensions are power of two. 
   SizeCommand sizecommand = new SizeCommand(256, 256, Leadtools.RasterSizeFlags.Bicubic); 
 
   sizecommand.Run(image); 
 
   FourierTransformInformation FTArray = new FourierTransformInformation(image); 
   // Apply FFT. 
   FastFourierTransformCommand command = new FastFourierTransformCommand(FTArray, FastFourierTransformCommandFlags.FastFourierTransform | FastFourierTransformCommandFlags.Gray); 
 
   command.Run(image); 
   LeadRect rcRect = new LeadRect(0, 0, image.Width / 2, image.Height / 2); 
   FrequencyFilterCommand FreqCommand = new FrequencyFilterCommand(FTArray, rcRect, FrequencyFilterCommandFlags.InsideX | FrequencyFilterCommandFlags.InsideY); 
 
   FastFourierTransformCommand InvCommand = new FastFourierTransformCommand(FTArray, FastFourierTransformCommandFlags.InverseFastFourierTransform | FastFourierTransformCommandFlags.Gray | FastFourierTransformCommandFlags.Scale | 
         FastFourierTransformCommandFlags.Both); 
   InvCommand.Run(image); 
 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS21\Resources\Images"; 
}

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Core 
 
Public Sub FrequencyFilterCommandExample() 
   Dim codecs As New RasterCodecs() 
   codecs.ThrowExceptionsOnInvalidImages = True 
 
   Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "ImageProcessingDemo\\FourierTransform.jpg")) 
 
   ' Prepare the command 
   ' Resize the image to make sure the image's dimensions are power of two. 
   Dim sizecommand As SizeCommand = New SizeCommand(256, 256, RasterSizeFlags.Bicubic) 
 
   sizecommand.Run(leadImage) 
 
   Dim FTArray As FourierTransformInformation = New FourierTransformInformation(leadImage) 
   ' Apply FFT. 
   Dim command As FastFourierTransformCommand = New FastFourierTransformCommand(FTArray, 
                                                                                FastFourierTransformCommandFlags.FastFourierTransform Or 
                                                                                FastFourierTransformCommandFlags.Gray) 
 
   command.Run(leadImage) 
   Dim rcRect As LeadRect = New LeadRect(0, 0, leadImage.Width \ 2, leadImage.Height \ 2) 
   Dim FreqCommand As FrequencyFilterCommand = New FrequencyFilterCommand(FTArray, rcRect, 
                                                                          FrequencyFilterCommandFlags.InsideX Or 
                                                                          FrequencyFilterCommandFlags.OutsideY) 
 
   Dim InvCommand As FastFourierTransformCommand = New FastFourierTransformCommand(FTArray, 
                                                                                   FastFourierTransformCommandFlags.InverseFastFourierTransform Or 
                                                                                   FastFourierTransformCommandFlags.Gray Or 
                                                                                   FastFourierTransformCommandFlags.Scale Or 
                                                                                   FastFourierTransformCommandFlags.Both) 
 
   InvCommand.Run(leadImage) 
 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\LEADTOOLS21\Resources\Images" 
End Class