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SubtractBackgroundCommand Class
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Leadtools.ImageProcessing.Core Namespace : SubtractBackgroundCommand Class



Removes the background from the image. Supported in Silverlight, Windows Phone 7

Object Model

SubtractBackgroundCommand Class

Syntax

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

Example

Run the Leadtools.ImageProcessing.Core.SubtractBackgroundCommand on an image.

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

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

   ' Prepare the command
   Dim command As SubtractBackgroundCommand = New SubtractBackgroundCommand
   command.RollingBall = 50
   command.BrightnessFactor = 100
   command.ShrinkingSize = SubtractBackgroundCommandType.DependOnRollingBallSize
   command.Flags = SubtractBackgroundCommandFlags.BackgroundIsDarker
   'Apply Subtract Background effect on the image.
   command.Run(leadImage)

End Sub

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class
C#Copy Code
public void SubtractBackgroundCommandExample()
   {
      // Load an image
      RasterCodecs codecs = new RasterCodecs();
      codecs.ThrowExceptionsOnInvalidImages = true;

      RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Master.jpg"));

      // Prepare the command
      SubtractBackgroundCommand command = new SubtractBackgroundCommand();
      command.RollingBall      = 50;
      command.BrightnessFactor = 100;
      command.ShrinkingSize    = SubtractBackgroundCommandType.DependOnRollingBallSize;
      command.Flags            = SubtractBackgroundCommandFlags.BackgroundIsDarker;
      //Apply Subtract Background effect on the image.
      command.Run(image);

   }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}
SilverlightCSharpCopy Code
public void SubtractBackgroundCommandExample(RasterImage image, Stream outStream)
{
   // Prepare the command
   SubtractBackgroundCommand command = new SubtractBackgroundCommand();
   command.RollingBall = 50;
   command.BrightnessFactor = 100;
   command.ShrinkingSize = SubtractBackgroundCommandType.DependOnRollingBallSize;
   command.Flags = SubtractBackgroundCommandFlags.BackgroundIsDarker;
   //Apply Subtract Background effect on the image.
   command.Run(image);
   // Save result image
   RasterCodecs codecs = new RasterCodecs();
   codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24);
   image.Dispose();
}
SilverlightVBCopy Code
Public Sub SubtractBackgroundCommandExample(ByVal image As RasterImage, ByVal outStream As Stream)
   ' Prepare the command
   Dim command As SubtractBackgroundCommand = New SubtractBackgroundCommand()
   command.RollingBall = 50
   command.BrightnessFactor = 100
   command.ShrinkingSize = SubtractBackgroundCommandType.DependOnRollingBallSize
   command.Flags = SubtractBackgroundCommandFlags.BackgroundIsDarker
   'Apply Subtract Background effect on the image.
   command.Run(image)
   ' Save result image
   Dim codecs As RasterCodecs = New RasterCodecs()
   codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24)
   image.Dispose()
End Sub

Remarks

  • This command is useful, especially with medical images and grayscale images in correcting non-uniform brightness.
  • The rolling ball algorithm works as follows:
    1. Consider the image to be a 3-D surface and the z-axis to be the intensity of the image [The component V from the HSV color space].
    2. Roll a 3-D ball beneath the surface so all the points of the ball are under the surface with one or more points of the ball tangent to the surface.
    3. The tangent points to the rolling ball are considered to be the background.
    4. Subtract the background from the original image.
  • The Rolling Ball Radius should be at least as large as the radius of the largest object in the image that is not part of the background to ensure the separation of the background from any objects.
  • A small radius allows the detection of small objects, whereas a larger radius will detect both small and large objects.
  • When subtracting the background, sometimes the result is dim. In such a case you can enhance the brightness after subtracting the background by using the brightness factor value, which functions similar to Leadtools.ImageProcessing.Color.MultiplyCommand. Passing 100 for the brightness factor leaves the brightness unchanged.
  • This command 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.
  • This command does not support signed data images.
  • This command does not support 32-bit grayscale images.
For more information, refer to Changing Brightness and Contrast.

Inheritance Hierarchy

System.Object
   Leadtools.ImageProcessing.RasterCommand
      Leadtools.ImageProcessing.Core.SubtractBackgroundCommand

Requirements

Target Platforms: Silverlight 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family, Windows Vista, Windows 7, MAC OS/X (Intel Only)

See Also