FourierTransformDisplayCommand Class

This command is used to display the results of a Fast Fourier Transform or a Discrete Fourier analysis as an image.

Object Model

Syntax

C#
Visual Basic
WinRT C#
Java
Objective-C
WinRT JavaScript
C++

public class FourierTransformDisplayCommand : Leadtools.ImageProcessing.RasterCommand, Leadtools.ImageProcessing.IRasterCommand

'Declaration

Public Class FourierTransformDisplayCommand 
   Inherits Leadtools.ImageProcessing.RasterCommand
   Implements Leadtools.ImageProcessing.IRasterCommand

'Usage

Dim instance As FourierTransformDisplayCommand

public sealed class FourierTransformDisplayCommand : Leadtools.ImageProcessing.IRasterCommand

@interface LTFourierTransformDisplayCommand : LTRasterCommand

function Leadtools.ImageProcessing.Core.FourierTransformDisplayCommand()

public ref class FourierTransformDisplayCommand : public Leadtools.ImageProcessing.RasterCommand, Leadtools.ImageProcessing.IRasterCommand

Remarks

This command is available in the Imaging Pro and above toolkits.

This command converts the Data property of the FourierTransformInformation object computed by FastFourierTransformCommand or DiscreteFourierTransformCommand commands into an image. The resulting image may be displayed such that it shows either the frequency harmonics amplitude data or phase data. The (0,0) frequency is located in the image center, positive X harmonics in the right half and positive Y harmonics located in the lower half of the image. Note: If a padding flag was used when creating the FourierTransformInformation instance and the image is not the same size as the frequency data after padding, the image will be re-created with the proper size.
This command does not work on regions. If the image has a region the command ignores it and processes the entire image.
The Run method image should be allocated prior to calling this command. The size of the image must be the same size as the image that was used to generate the information in the Data property of the FourierTransformInformation object.
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 data images.
This command does not support 32-bit grayscale images.

For more information, refer to Removing Noise.

Example

Runs the FourierTransformDisplayCommand on an image, applies the Discrete Fourier Transform command to it, and displays the data.

C#
Visual Basic
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Copy Code

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.ImageProcessing.Core

   
Public Sub FourierTransformDisplayCommandExample()
   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
   Dim FTArray As FourierTransformInformation = New FourierTransformInformation(leadImage)
   Dim rcRange As LeadRect = New LeadRect(0, 0, leadImage.Width - 1, leadImage.Height - 1)
   Dim DFTcommand As DiscreteFourierTransformCommand = New DiscreteFourierTransformCommand
   Dim command As FourierTransformDisplayCommand = New FourierTransformDisplayCommand

   DFTcommand.FourierTransformInformation = FTArray
   DFTcommand.Range = rcRange
   DFTcommand.Flags = DiscreteFourierTransformCommandFlags.DiscreteFourierTransform _
   Or DiscreteFourierTransformCommandFlags.Gray _
   Or DiscreteFourierTransformCommandFlags.Range _
   Or DiscreteFourierTransformCommandFlags.InsideX _
   Or DiscreteFourierTransformCommandFlags.OutsideY
   ' apply DFT
   DFTcommand.Run(leadImage)

   command.Flags = FourierTransformDisplayCommandFlags.Log Or FourierTransformDisplayCommandFlags.Magnitude
   command.FourierTransformInformation = FTArray
   'plot frequency magnitude
   command.Run(leadImage)

End Sub

Public NotInheritable Class LEAD_VARS
Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class

using Leadtools;
using Leadtools.Codecs;
using Leadtools.ImageProcessing.Core;

      
public void FourierTransformDisplayCommandExample()
{
   // 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
   FourierTransformInformation FTArray = new FourierTransformInformation(image);
   LeadRect rcRange = new LeadRect(0, 0, image.Width - 1, image.Height - 1);
   DiscreteFourierTransformCommand DFTcommand = new DiscreteFourierTransformCommand();
   FourierTransformDisplayCommand  command = new FourierTransformDisplayCommand();

   DFTcommand.FourierTransformInformation = FTArray;
   DFTcommand.Range = rcRange;
   DFTcommand.Flags = DiscreteFourierTransformCommandFlags.DiscreteFourierTransform | 
      DiscreteFourierTransformCommandFlags.Gray    | 
      DiscreteFourierTransformCommandFlags.Range   | 
      DiscreteFourierTransformCommandFlags.InsideX | 
      DiscreteFourierTransformCommandFlags.InsideY; 
   // apply DFT
   DFTcommand.Run(image);

   command.Flags = FourierTransformDisplayCommandFlags.Log | FourierTransformDisplayCommandFlags.Magnitude;
   command.FourierTransformInformation = FTArray;
   //plot frequency magnitude.
   command.Run(image);

}

static class LEAD_VARS
{
public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}

function FourierTransformDisplayCommandExample()
{
   var codecs = new Leadtools.Codecs.RasterCodecs();
   codecs.throwExceptionsOnInvalidImages = true;

   // Load the image
   var srcFileName = "Assets\\Image1.cmp";
   return Tools.AppInstallFolder().getFileAsync(srcFileName).then(function (loadFile) {
      return codecs.loadAsync(Leadtools.LeadStreamFactory.create(loadFile));
   }).then(function (image) {
      // Prepare the command
      with (Leadtools.ImageProcessing.Core) {
         var FTArray = new FourierTransformInformation(image);
         var rcRange = Leadtools.LeadRectHelper.create(0, 0, image.width - 1, image.height - 1);
         var DFTcommand = new DiscreteFourierTransformCommand();
         var command = new FourierTransformDisplayCommand();
         
         DFTcommand.fourierTransformInformation = FTArray;
         DFTcommand.range = rcRange;
         DFTcommand.flags = DiscreteFourierTransformCommandFlags.discreteFourierTransform | 
            DiscreteFourierTransformCommandFlags.gray    | 
            DiscreteFourierTransformCommandFlags.range   | 
            DiscreteFourierTransformCommandFlags.insideX | 
            DiscreteFourierTransformCommandFlags.insideY; 
         // apply DFT
         DFTcommand.run(image);
         
         command.flags = FourierTransformDisplayCommandFlags.log | FourierTransformDisplayCommandFlags.magnitude;
         command.fourierTransformInformation = FTArray;
         //plot frequency magnitude.
         command.run(image);
      }
   });
}

using Leadtools;
using Leadtools.Codecs;
using Leadtools.ImageProcessing.Core;

      
public async Task FourierTransformDisplayCommandExample()
{
   // Load an image
   RasterCodecs codecs = new RasterCodecs();
   codecs.ThrowExceptionsOnInvalidImages = true;
   // Load the image
   string srcFileName = @"Assets\Image1.cmp";
   StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(srcFileName);
   RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile));

   // Prepare the command
   FourierTransformInformation FTArray = new FourierTransformInformation(image);
   LeadRect rcRange = LeadRectHelper.Create(0, 0, image.Width - 1, image.Height - 1);
   DiscreteFourierTransformCommand DFTcommand = new DiscreteFourierTransformCommand();
   FourierTransformDisplayCommand  command = new FourierTransformDisplayCommand();

   DFTcommand.FourierTransformInformation = FTArray;
   DFTcommand.Range = rcRange;
   DFTcommand.Flags = DiscreteFourierTransformCommandFlags.DiscreteFourierTransform | 
      DiscreteFourierTransformCommandFlags.Gray    | 
      DiscreteFourierTransformCommandFlags.Range   | 
      DiscreteFourierTransformCommandFlags.InsideX | 
      DiscreteFourierTransformCommandFlags.InsideY; 
   // apply DFT
   DFTcommand.Run(image);

   command.Flags = FourierTransformDisplayCommandFlags.Log | FourierTransformDisplayCommandFlags.Magnitude;
   command.FourierTransformInformation = FTArray;
   //plot frequency magnitude.
   command.Run(image);

}

Requirements

Target Platforms

Reference