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HistogramEqualizeCommand Class

Summary

Linearizes the number of pixels, in an image, based on the specified color space. This can be used to bring out the detail in dark areas of an image. This function is useful for pre-processing images for the purpose of improving barcode recognition results.

Syntax

Java

Objective-C

WinRT C#

C++

public class HistogramEqualizeCommand : Leadtools.Imageprocessing.Leadtools.ImageProcessing.RasterCommand, Leadtools.Imageprocessing.Leadtools.ImageProcessing.IRasterCommand

Public Class HistogramEqualizeCommand  
   Inherits Leadtools.Imageprocessing.Leadtools.ImageProcessing.RasterCommand 
   Implements Leadtools.Imageprocessing.Leadtools.ImageProcessing.IRasterCommand

public sealed class HistogramEqualizeCommand : Leadtools.Imageprocessing.Leadtools.ImageProcessing.IRasterCommand

@interface LTHistogramEqualizeCommand : LTRasterCommand

public class HistogramEqualizeCommand extends RasterCommand

function Leadtools.ImageProcessing.Color.HistogramEqualizeCommand()

public ref class HistogramEqualizeCommand : public Leadtools.Imageprocessing.Leadtools.ImageProcessing.RasterCommand, Leadtools.Imageprocessing.Leadtools.ImageProcessing.IRasterCommand

Remarks

Previously this class only equalized the number of pixels per gray level, using a gray level representation of the image. This functionality is now obtained by passing HistogramEqualizeType.Gray for the Type property.
For the best results, set Type to HistogramEqualizeType.Yuv
This class can process the whole image or a region of the image.
This class 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 32-bit grayscale images.
This command supports signed/unsigned data images.

For more information, refer to Changing Brightness and Contrast.

Example

Run the HistogramEqualizeCommand on an image and apply histogram equalization with YUV color space.

WinRT C#

Silverlight C#

Silverlight VB

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing.Color 
 
    
Public Sub HistogramEqualizeCommandExample() 
   Dim codecs As New RasterCodecs() 
   codecs.ThrowExceptionsOnInvalidImages = True 
   Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1.CMP")) 
 
   ' Prepare the command 
   Dim command As HistogramEqualizeCommand = New HistogramEqualizeCommand 
   'Histogram equalize the image. 
   command.Type = HistogramEqualizeType.Yuv 
 
   command.Run(leadImage) 
   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:\Users\Public\Documents\LEADTOOLS Images" 
End Class

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Color; 
 
       
public void HistogramEqualizeCommandExample() 
{ 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1.CMP")); 
 
   // Prepare the command 
   HistogramEqualizeCommand command = new HistogramEqualizeCommand(); 
   //Histogram equalize the image. 
   command.Type   = HistogramEqualizeType.Yuv; 
   command.Run(image); 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Result.jpg"), RasterImageFormat.Jpeg, 24); 
 
} 
 
static class LEAD_VARS 
{ 
public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
}

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Color; 
 
       
public async Task HistogramEqualizeCommandExample() 
{ 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
   // Load the image 
   string srcFileName = @"Assets\Image1.cmp"; 
   StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(srcFileName); 
   RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile)); 
 
   // Prepare the command 
   HistogramEqualizeCommand command = new HistogramEqualizeCommand(); 
   //Histogram equalize the image. 
   command.Type   = HistogramEqualizeType.Yuv; 
   command.Run(image); 
 
   string destFileName = @"result.jpg"; 
   StorageFile saveFile = await Tools.AppLocalFolder.CreateFileAsync(destFileName); 
   await codecs.SaveAsync(image, LeadStreamFactory.Create(saveFile), RasterImageFormat.Jpeg, 0); 
}

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Examples; 
 
public void HistogramEqualizeCommandExample(RasterImage image, Stream outStream) 
{ 
   // Prepare the command 
   HistogramEqualizeCommand command = new HistogramEqualizeCommand(); 
   //Histogram equalize the image. 
   command.Type   = HistogramEqualizeType.Yuv; 
   command.Run(image); 
   // Save result image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24); 
   image.Dispose(); 
}

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing.Color 
 
Public Sub HistogramEqualizeCommandExample(ByVal image As RasterImage, ByVal outStream As Stream) 
   ' Prepare the command 
   Dim command As HistogramEqualizeCommand = New HistogramEqualizeCommand() 
   'Histogram equalize the image. 
   command.Type = HistogramEqualizeType.Yuv 
   command.Run(image) 
   ' Save result image 
   Dim codecs As RasterCodecs = New RasterCodecs() 
   codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24) 
   image.Dispose() 
End Sub