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SubtractBackgroundCommand Class

Summary

Removes the background from the image.

Syntax
C#
VB
Java
Objective-C
C++
public class SubtractBackgroundCommand : RasterCommand 
Public Class SubtractBackgroundCommand  
   Inherits RasterCommand 
@interface LTSubtractBackgroundCommand : LTRasterCommand 
public class SubtractBackgroundCommand extends RasterCommand 
public ref class SubtractBackgroundCommand : public RasterCommand   

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 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.

Example

Run the SubtractBackgroundCommand on an image.

C#
VB
using Leadtools; 
using Leadtools.ImageProcessing; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Core; 
 
public void SubtractBackgroundCommandExample() 
{ 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, @"ImageProcessingDemo\Image4.Tif")); 
 
   // 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"; 
} 
Imports Leadtools 
Imports Leadtools.ImageProcessing 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing.Core 
 
Public Sub SubtractBackgroundCommandExample() 
   Dim codecs As New RasterCodecs() 
   codecs.ThrowExceptionsOnInvalidImages = True 
 
   Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "ImageProcessingDemo\\Image4.Tif")) 
 
   ' 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#[Silverlight C# Example] 
using Leadtools; 
using Leadtools.Examples; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Core; 
 
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(); 
} 
vb[Silverlight VB Example] 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing.Core 
 
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 

Requirements

Target Platforms

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Leadtools.ImageProcessing.Core Assembly