ApplyVoiLookupTableCommand Class

Sets up the paint or paint and image processing methods' window leveling options for a specific image through a lookup-table (LookupTable). This class is available in the Document/Medical Toolkits only.

Object Model

Syntax

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

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

'Declaration
 
Public Class ApplyVoiLookupTableCommand 
   Inherits Leadtools.ImageProcessing.RasterCommand
   Implements Leadtools.ImageProcessing.IRasterCommand

'Usage
 
Dim instance As ApplyVoiLookupTableCommand

public sealed class ApplyVoiLookupTableCommand : Leadtools.ImageProcessing.IRasterCommand

function Leadtools.ImageProcessing.Core.ApplyVoiLookupTableCommand()

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

Remarks

This class sets up the paint or paint and image processing methods' window leveling options for a specific image through a lookup-table (LookupTable). In the DICOM world, this is referred to as "applying a non-linear VOI LookupTable".
This class will remap the LookupTable used to display and process an image by applying a user-defined lookup table. In the DICOM world this is referred to as applying a "non-linear VOI LookupTable". The DICOM standard states:
"A VOI LookupTable defines the transformation of the modality pixel values into pixel values that are meaningful for print, display, etc. This transformation is applied after any Modality LookupTable". Please see "VOI LookupTable Module Attributes" in the DICOM standard for more details.
This class does not change the image data; it only updates the entries inside the image display LookupTable.
The value is remapped according to the LookupTable (values smaller than FirstStoredPixelValueMapped (property of the DicomLookupTableDescriptor class) are mapped to the first LookupTable entry, while values greater than FirstStoredPixelValueMapped (property of the DicomLookupTableDescriptor class) + LookupTable->Length are mapped to the last LookupTable entry).
It is recommended to always set the VoiLookupTableCommandFlags flag.
In the DICOM world you will need to set the VoiLookupTableCommandFlags flag if the photometric interpretation of the image is "MONOCHROME1", where the minimum grayscale value is intended to be displayed as white after any VOI gray scale transformations have been performed.
This class supports 12 and 16-bit grayscale. Support for 12 and 16-bit grayscale is available only in the Document/Medical toolkits.
This command does not support 32-bit grayscale images.

For more information, refer to Changing Brightness and Contrast.

In Silverlight and Windows Phone versions of LEADTOOLS, this image processing command will fail if the image data for the RasterImage object is stored internally using a Silverlight WriteableBitmap object. For more information, refer to Image Processing Command Limitations in Silverlight.

Example

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

Public Sub ApplyVoiLookupTableCommandExample()
   Dim codecs As New RasterCodecs()
   codecs.ThrowExceptionsOnInvalidImages = True

   Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE2.dcm"))

   ' Prepare the command
   Dim i As Integer
   Dim pLookupTable() As Short
   ReDim pLookupTable(65536)
   Dim LookupTableDescriptor As DicomLookupTableDescriptor = New DicomLookupTableDescriptor

   For i = 0 To 65536

      If (i < 30) Then
         pLookupTable(i) = 0

      Else
         If (i > 630) Then
            pLookupTable(i) = 630
         Else
            pLookupTable(i) = CType(i, Int16)
         End If

      End If

   Next

   ' fill the LookupTableDescriptor object
   LookupTableDescriptor.FirstStoredPixelValueMapped = 0
   LookupTableDescriptor.EntryBits = 16

   Dim command As ApplyVoiLookupTableCommand = New ApplyVoiLookupTableCommand
   command.Flags = VoiLookupTableCommandFlags.None
   command.LookupTable = pLookupTable
   command.LookupTableDescriptor = LookupTableDescriptor
   command.Run(leadImage)

End Sub

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

public void ApplyVoiLookupTableCommandExample()
   {
      // Load an image
      RasterCodecs codecs = new RasterCodecs();
      codecs.ThrowExceptionsOnInvalidImages = true;

      RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE2.dcm"));

      // Prepare the command
      int                i; 
      short[] pLookupTable = new short[0x10000];
      DicomLookupTableDescriptor LookupTableDescriptor = new DicomLookupTableDescriptor();

      for(i = 0; i < 0x10000; i++)
      {
         if(i < 30) 
         {
            pLookupTable[i] = 0;
         }
         else
            if(i > 630) 
            pLookupTable[i] = 630;
         else
            pLookupTable[i] = (short)i;
      }

      // fill the LookupTableDescriptor object
      LookupTableDescriptor.FirstStoredPixelValueMapped = 0;
      LookupTableDescriptor.EntryBits = 16;

      ApplyVoiLookupTableCommand command = new ApplyVoiLookupTableCommand();
      command.Flags                      = VoiLookupTableCommandFlags.None;
      command.LookupTable                = pLookupTable;
      command.LookupTableDescriptor      = LookupTableDescriptor;
      command.Run(image);

   }

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

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

   // Load the image
   var srcFileName = "Assets\\Image2.dcm";
   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) {
         // Prepare the command
         var i; 
         var pLookupTable = new Array();; 
         var LookupTableDescriptor = new DicomLookupTableDescriptor();
         
         for(i = 0; i < 0x10000; i++)
         {
            if(i < 30) 
            {
               pLookupTable[i] = 0;
            }
            else
               if(i > 630) 
                  pLookupTable[i] = 630;
               else
                  pLookupTable[i] = parseInt(i);
         }
         
         // fill the LookupTableDescriptor object
         LookupTableDescriptor.firstStoredPixelValueMapped = 0;
         LookupTableDescriptor.entryBits = 16;
         
         var command = new ApplyVoiLookupTableCommand();
         command.flags = VoiLookupTableCommandFlags.none;
         command.lookupTable = pLookupTable;
         command.lookupTableDescriptor = LookupTableDescriptor;
         command.run(image);
      }
   });
}

[TestMethod]
public async Task ApplyVoiLookupTableCommandExample()
{
   // Load an image
   RasterCodecs codecs = new RasterCodecs();
   codecs.ThrowExceptionsOnInvalidImages = true;
   // Load the image
   string srcFileName = @"Assets\Image2.dcm";
   StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(srcFileName);
   RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile));

   // Prepare the command
   int                i; 
   short[] pLookupTable = new short[0x10000];
   DicomLookupTableDescriptor LookupTableDescriptor = new DicomLookupTableDescriptor();

   for(i = 0; i < 0x10000; i++)
   {
      if(i < 30) 
      {
         pLookupTable[i] = 0;
      }
      else
         if(i > 630) 
         pLookupTable[i] = 630;
      else
         pLookupTable[i] = (short)i;
   }

   // fill the LookupTableDescriptor object
   LookupTableDescriptor.FirstStoredPixelValueMapped = 0;
   LookupTableDescriptor.EntryBits = 16;

   ApplyVoiLookupTableCommand command = new ApplyVoiLookupTableCommand();
   command.Flags                      = VoiLookupTableCommandFlags.None;
   command.LookupTable                = pLookupTable;
   command.LookupTableDescriptor      = LookupTableDescriptor;
   command.Run(image);

}

public void ApplyVoiLookupTableCommandExample(RasterImage image, Stream outStream)
{
   // Prepare the command
   int i;
   short[] pLookupTable = new short[0x10000];
   DicomLookupTableDescriptor LookupTableDescriptor = new DicomLookupTableDescriptor();
   for(i = 0; i < 0x10000; i++)
   {
      if(i < 30) 
      {
         pLookupTable[i] = 0;
      }
      else
         if(i > 630) 
         pLookupTable[i] = 630;
      else
         pLookupTable[i] = (short)i;
   }

   // fill the LookupTableDescriptor object
   LookupTableDescriptor.FirstStoredPixelValueMapped = 0;
   LookupTableDescriptor.EntryBits = 16;

   ApplyVoiLookupTableCommand command = new ApplyVoiLookupTableCommand();
   command.Flags                      = VoiLookupTableCommandFlags.None;
   command.LookupTable                = pLookupTable;
   command.LookupTableDescriptor      = LookupTableDescriptor;
   command.Run(image);

   // Save result image
   RasterCodecs codecs = new RasterCodecs();
   codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24);
   image.Dispose();
}

Public Sub ApplyVoiLookupTableCommandExample(ByVal image As RasterImage, ByVal outStream As Stream)
   ' Prepare the command
   Dim i As Integer
   Dim pLookupTable As Short() = New Short(&H10000 - 1){}
   Dim LookupTableDescriptor As DicomLookupTableDescriptor = New DicomLookupTableDescriptor()
   i = 0
   Do While i < &H10000
      If i < 30 Then
         pLookupTable(i) = 0
      Else
         If i > 630 Then
         pLookupTable(i) = 630
      Else
         pLookupTable(i) = CShort(i)
      End If
      End If
      i += 1
   Loop

   ' fill the LookupTableDescriptor object
   LookupTableDescriptor.FirstStoredPixelValueMapped = 0
   LookupTableDescriptor.EntryBits = 16

   Dim command As ApplyVoiLookupTableCommand = New ApplyVoiLookupTableCommand()
   command.Flags = VoiLookupTableCommandFlags.None
   command.LookupTable = pLookupTable
   command.LookupTableDescriptor = LookupTableDescriptor
   command.Run(image)

   ' Save result image
   Dim codecs As RasterCodecs = New RasterCodecs()
   codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24)
   image.Dispose()
End Sub

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

ApplyVoiLookupTableCommand Members
Leadtools.ImageProcessing.Core Namespace
Changing Brightness and Contrast
ApplyLinearVoiLookupTableCommand Class
Leadtools.ImageProcessing.Color.RemapIntensityCommand
ApplyModalityLookupTableCommand Class
ApplyLinearModalityLookupTableCommand Class
Leadtools.ImageProcessing.Color.AdjustTintCommand
Leadtools.ImageProcessing.Color.GammaCorrectExtendedCommand