Leadtools.ImageProcessing.Color Send comments on this topic. | Back to Introduction - All Topics | Help Version 16.5.9.25
ColorLevelCommand Class
See Also  Members   Example 



Applies color leveling to an image. It changes the image shadows, midtones and highlights. This function is useful for pre-processing images for the purpose of improving barcode recognition results.

Object Model





Syntax

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

Example

Run the ColorLevelCommand on an image.

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

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

   ' Prepare the command
   Dim blue As ColorLevelCommandData = New ColorLevelCommandData
   Dim master As ColorLevelCommandData = New ColorLevelCommandData
   ' Specify Image levels
   blue.MinimumInput = 20
   blue.MaximumInput = 200
   blue.MinimumOutput = 0
   blue.MaximumOutput = 255
   blue.Gamma = 100
   ' Master will cause the image to be Inversed
   master.MinimumInput = 0
   master.MaximumInput = 255
   master.MinimumOutput = 255
   master.MaximumOutput = 0
   master.Gamma = 100
   ' Level the Blue and Master channels
   Dim command As ColorLevelCommand = New ColorLevelCommand(master, Nothing, Nothing, blue, ColorLevelCommandFlags.Blue Or ColorLevelCommandFlags.Master)
   command.Run(leadImage)
   codecs.Save(leadImage, LeadtoolsExamples.Common.ImagesPath.Path + "Result.jpg", RasterImageFormat.Jpeg, 24)

   RasterCodecs.Shutdown()
End Sub
C#Copy Code
public void ColorLevelCommandExample() 
{ 
   // Load an image 
   RasterCodecs.Startup(); 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
 
   RasterImage image = codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "Master.jpg"); 
 
   // Prepare the command 
   ColorLevelCommandData blue    = new ColorLevelCommandData(); 
   ColorLevelCommandData master  = new ColorLevelCommandData(); 
   //Specify Image levels 
   blue.MinimumInput    = 20; 
   blue.MaximumInput    = 200; 
   blue.MinimumOutput   = 0; 
   blue.MaximumOutput   = 255; 
   blue.Gamma           = 100; 
   // Master will cause the image to be Inversed 
   master.MinimumInput  = 0; 
   master.MaximumInput  = 255; 
   master.MinimumOutput = 255; 
   master.MaximumOutput = 0; 
   master.Gamma         = 100; 
   // Level the Blue and Master channels 
   ColorLevelCommand command = new ColorLevelCommand(master, null, null, blue, ColorLevelCommandFlags.Blue | ColorLevelCommandFlags.Master); 
   command.Run(image); 
   codecs.Save(image, LeadtoolsExamples.Common.ImagesPath.Path + "Result.jpg", RasterImageFormat.Jpeg, 24); 
 
   RasterCodecs.Shutdown(); 
}

Remarks

  • The members of the ColorLevelCommandData class tell the ColorLevelCommand what constitutes shadows, midtones, and highlights and how to remap the shadows, midtones and highlights.
  • Control the amount of image balance and leveling by controlling the values of the MinimumInput, MaximumInput, MinimumOutput, MaximumOutput, and Gamma members of the ColorLevelCommandData class.
    • The MinimumInput property of the ColorLevelCommandData class defines what the method interprets as shadows for that color channel. Any value less than or equal to MinimumInput is considered a shadow.
    • The MaximumInput property of the ColorLevelCommandData class defines what the method interprets as highlights for that color channel. Any value greater than or equal to MaximumInput is considered a highlight.
    • The value of the MaximumInput property must be greater than the value of the MinimumInput property by at least 2.
    • Midtones are those values between MinimumInput and MaximumInput.
    • The MinimumOutput property is the value to which the shadows will be mapped.
    • The MaximumOutput property is the value to which the highlights will be mapped.
    • The Gamma property is used to modify the midtone values
  • If only ColorLevelCommandFlags.Master is set in the Flags property, then the rest of the channels will still be affected.
  • If the image is a grayscale image, then you must set ColorLevelCommandFlags.Master in the Flags property, otherwise the class will not have any effect.
  • If MinimumOutput > MaximumOutput then the image's shadows and highlights will be inverted.
  • 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.

For more information, refer to Changing Brightness and Contrast. For more information, refer to Correcting Colors.

Inheritance Hierarchy

System.Object
   Leadtools.ImageProcessing.RasterCommand
      Leadtools.ImageProcessing.Color.ColorLevelCommand

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