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ZeroToNegativeCommand Class
See Also  Members   Example 
Leadtools.ImageProcessing.Core Namespace : ZeroToNegativeCommand Class



Converts a grayscale unsigned image to a signed image by shifting the image data to the negative side by the amount specified by the user.

Syntax

Visual Basic (Declaration) 
Public Class ZeroToNegativeCommand 
   Inherits RasterCommand
   Implements IRasterCommand 
Visual Basic (Usage)Copy Code
Dim instance As ZeroToNegativeCommand
C# 
public class ZeroToNegativeCommand : RasterCommand, IRasterCommand 
C++/CLI 
public ref class ZeroToNegativeCommand : public RasterCommand, IRasterCommand 

Example

This command will apply MultiscaleEnhancementCommand on a signed image, but since MultiscaleEnhancementCommand doesn't support signed images, we will convert the image to unsigned image, apply the effect, and then convert it back to signed image.

Visual BasicCopy Code
Public Sub ZeroToNegativeCommandExample()
   RasterCodecs.Startup()
   Dim codecs As New RasterCodecs()
   codecs.ThrowExceptionsOnInvalidImages = True

   Dim leadImage As RasterImage = codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "Beauty16.jpg")

   ' Prepare the command
   ' Convert the image to unsigned image by shifting the negative values to become positive.
   Dim MinToZCommand As MinimumToZeroCommand = New MinimumToZeroCommand
   MinToZCommand.Run(leadImage)

   ' Apply multiscale enhancement
   Dim MultiScaleCommand As MultiscaleEnhancementCommand = New MultiscaleEnhancementCommand(2000, 4, -1, 0, 0, MultiscaleEnhancementCommandType.Gaussian, MultiscaleEnhancementCommandFlags.EdgeEnhancement)

   ' Convert the image back to signed by shifting the same amount in the negative side.
   Dim command As ZeroToNegativeCommand = New ZeroToNegativeCommand
   command.MinimumInput = -32767
   command.MaximumInput = 32766
   command.MinimumOutput = 0
   command.MaximumOutput = 65535
   command.ShiftAmount = MinToZCommand.ShiftAmount
   command.Run(leadImage)

   RasterCodecs.Shutdown()
End Sub
C#Copy Code
public void ZeroToNegativeCommandExample() 
{ 
   // Load an image 
   RasterCodecs.Startup(); 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
 
   RasterImage image = codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "Beauty16.jpg"); 
 
   // Prepare the command 
   // Convert the image to unsigned image by shifting the negative values to become positive. 
   MinimumToZeroCommand MinToZCommand = new MinimumToZeroCommand(); 
   MinToZCommand.Run(image);  
 
   // Apply multiscale enhancement 
   MultiscaleEnhancementCommand MultiScaleCommand = new MultiscaleEnhancementCommand(2000, 4, -1, 0, 0, MultiscaleEnhancementCommandType.Gaussian, MultiscaleEnhancementCommandFlags.EdgeEnhancement); 
 
   // Convert the image back to signed by shifting the same amount in the negative side. 
   ZeroToNegativeCommand command = new ZeroToNegativeCommand(); 
   command.MinimumInput  = -32767; 
   command.MaximumInput  = 32766; 
   command.MinimumOutput = 0; 
   command.MaximumOutput = 65535; 
   command.ShiftAmount   = MinToZCommand.ShiftAmount; 
   command.Run(image); 
 
   RasterCodecs.Shutdown(); 
}

Remarks

This command is similar to ConvertUnsignedToSignedCommand. However, MinimumToZeroCommand updates MinimumToZeroCommand.ShiftAmount with the value by which the intensity values were shifted. The updated MinimumToZeroCommand.ShiftAmount value can be passed to ZeroToNegativeCommand to convert the image back to signed (i.e. after using image processing command that works in unsigned 12-16 bit grayscale image).
MinimumToZeroCommand and ZeroToNegativeCommand are most often used in concert with one or more image processing or analysis commands. MinimumToZeroCommand converts signed data to unsigned data, in preparation for image processing or analysis commands that work on unsigned image data. After the image processing or analysis is performed, ZeroToNegativeCommand can be used to converts the unsigned data back to signed data.
This command is used usually after the command MinimumToZeroCommand.
This command updates the Signed property of the RasterImage.
This command also updates the MinValue and MaxValue properties of the RasterImage.
This command supports signed data images and supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available only in the Document/Medical toolkits. However, this command does not support 8-bit images.
This command does not support 32-bit grayscale images.

Inheritance Hierarchy

System.Object
   Leadtools.ImageProcessing.RasterCommand
      Leadtools.ImageProcessing.Core.ZeroToNegativeCommand

Requirements

Target Platforms: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also