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AutoColorLevelCommand Class

Applies one of several types of automatic color leveling to an image. This function is useful for pre-processing images for the purpose of improving barcode recognition results.
public class AutoColorLevelCommand : RasterCommand 
Public Class AutoColorLevelCommand  
   Inherits RasterCommand 
@interface LTAutoColorLevelCommand : LTRasterCommand 
public class AutoColorLevelCommand extends RasterCommand 
public ref class AutoColorLevelCommand : public RasterCommand   
  • This command makes the dark values darker and the light values lighter, which automatically enhances shadows and brightens the image. It also maximizes the tonal range of the image. It enhances the contrast and intensity using the image's histogram and a color distribution-based algorithm.
  • The properties in the AutoColorLevelCommand Class will be updated with the MinimumInput, MaximumInput, MinimumOutput, MaximumOutput and Gamma values used by a method for the appropriate channel(s).
  • If you set the AutoColorLevelCommandFlags.NoProcess flag in the Flag property, the ColorLevelCommandData will be updated with the color leveling information used by the AutoColorLevelCommand. If you then pass the updated ColorLevelCommandData structures to the ColorLevelCommand, you will obtain the same result that you would have obtained if you had called the AutoColorLevelCommand with the leveling flag by itself.
  • If the image is a grayscale image, then AutoColorLevelCommandType.Level, AutoColorLevelCommandType.Contrast and AutoColorLevelCommandType.Intensity give identical results. Also the Master, Red, Green and Blue properties will have the same values.
  • As an example, the following figure shows an image before any automatic color leveling has been performed:


    The following figure shows what would happen if you start with the original image and apply the AutoColorLevelCommand using AutoColorLevelCommandType.Level flag.


    The following figure shows what would happen if you start with the original image and apply the AutoColorLevelCommand using AutoColorLevelCommandType.Intensity flag.


    The following figure shows what would happen if you start with the original image and apply the AutoColorLevelCommand using AutoColorLevelCommandType.Contrast flag.

  • 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 supports unsigned data images, but not signed ones.
  • This command does not support 32-bit grayscale images.

For more information, refer to Correcting Colors.


Run the AutoColorLevelCommand on an image.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Color; 
public void AutoColorLevelCommandExample() 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, @"ImageProcessingDemo\Image1.jpg")); 
   // Prepare the command 
   AutoColorLevelCommand command = new AutoColorLevelCommand(); 
   // Apply "Auto Leveling" to the image. 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Result.jpg"), RasterImageFormat.Jpeg, 24); 
static class LEAD_VARS 
   public const string ImagesDir = @"C:\LEADTOOLS21\Resources\Images"; 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing.Color 
Public Sub AutoColorLevelCommandExample() 
   Dim codecs As New RasterCodecs() 
   codecs.ThrowExceptionsOnInvalidImages = True 
   Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "ImageProcessingDemo\\Image1.jpg")) 
   ' Prepare the command 
   Dim command As AutoColorLevelCommand = New AutoColorLevelCommand 
   ' Apply "Auto Leveling" to the image. 
   codecs.Save(leadImage, Path.Combine(LEAD_VARS.ImagesDir, "Result.jpg"), RasterImageFormat.Jpeg, 24) 
End Sub 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\LEADTOOLS21\Resources\Images" 
End Class 

Target Platforms

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Leadtools.ImageProcessing.Color Assembly