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HistogramEqualize Method

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 operation is useful for pre-processing images for the purpose of improving barcode recognition results.

Syntax

C#
VB
C++
[OperationContractAttribute(Action="HistogramEqualize", 
   AsyncPattern=false, 
   IsOneWay=false, 
   IsInitiating=true, 
   IsTerminating=false)] 
[FaultContractAttribute(System.Type)] 
public CommandResponse HistogramEqualize( 
   HistogramEqualizeRequest request 
) 
  
<FaultContractAttribute(DetailType=Leadtools.Services.Raster.FaultContracts.RasterFault,  
   Action="",  
   Name="",  
   Namespace="",  
   ProtectionLevel=ProtectionLevel.None,  
   HasProtectionLevel=False)> 
<OperationContractAttribute("HistogramEqualize")> 
Function HistogramEqualize( _ 
   ByVal request As Leadtools.Services.Imageprocessing.Datacontracts.HistogramEqualizeRequest _ 
) As Leadtools.Services.Imageprocessing.Datacontracts.CommandResponse 
[FaultContractAttribute(DetailType=Leadtools.Services.Raster.FaultContracts.RasterFault,  
   Action="",  
   Name="",  
   Namespace="",  
   ProtectionLevel=ProtectionLevel.None,  
   HasProtectionLevel=false)] 
[OperationContractAttribute("HistogramEqualize")] 
Leadtools.Services.Imageprocessing.Datacontracts.CommandResponse^ HistogramEqualize(  
   Leadtools.Services.Imageprocessing.Datacontracts.HistogramEqualizeRequest^ request 
)  

Parameters

request
A System.Runtime.Serialization.DataContractAttribute containing the data that will be used in this HistogramEqualize operation.

Return Value

A System.Runtime.Serialization.DataContractAttribute containing the modified image resulting from the HistogramEqualize operation.

Remarks
  • Previously this operation only equalized the number of pixels per gray level, using a gray level representation of the image. This operation is now obtained by setting HistogramEqualizeType.Gray for the Type property.
  • For the best results, set Type to HistogramEqualizeType.Yuv.
  • This operation can process the whole image or a region of the image.
  • This operation 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 operation does not support 32-bit grayscale images.
Example

C#
VB
using Leadtools.Services; 
 
public void HistogramEqualizeExample() 
{ 
   ColorProcessingServiceClient client = new ColorProcessingServiceClient(); 
 
   RawBinaryData sourceBinaryData = new RawBinaryData(); 
   sourceBinaryData.Data = File.ReadAllBytes(Path.Combine(LEAD_VARS.ImagesDir, "image1.cmp")); 
 
   RasterConvertOptions convertOptions = new RasterConvertOptions(); 
 
   convertOptions.Source = sourceBinaryData; 
   convertOptions.Destination = null; 
   convertOptions.Format = RasterImageFormat.Bmp; 
   convertOptions.FirstPage = 1; 
   convertOptions.LastPage = 1; 
   convertOptions.BitsPerPixel = 24; 
   convertOptions.QualityFactor = 2; 
 
   HistogramEqualizeRequest request = new HistogramEqualizeRequest(); 
 
   request.ConvertOptions = convertOptions; 
   request.RegionData = null; 
   request.Type = HistogramEqualizeType.Yuv; 
 
   CommandResponse response = client.HistogramEqualize(request); 
   if (response.Destination != null) 
   { 
      if (response.Destination is RawBinaryData) 
         File.WriteAllBytes(Path.Combine(LEAD_VARS.ImagesDir, "HistogramEqualize.bmp"), (response.Destination as RawBinaryData).Data); 
   } 
 
   client.Close(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
} 
Imports Leadtools.Services 
Imports Leadtools.Services.datacontracts._2009._01 
Imports Leadtools.Services.raster.datacontracts._2009._01 
Imports Leadtools.Services.ImageProcessing.datacontracts._2009._01 
 
Public Sub HistogramEqualizeExample() 
   Dim client As ColorProcessingServiceClient = New ColorProcessingServiceClient() 
 
   Dim sourceBinaryData As RawBinaryData = New RawBinaryData() 
   sourceBinaryData.Data = File.ReadAllBytes(Path.Combine(LEAD_VARS.ImagesDir, "image1.cmp")) 
 
   Dim convertOptions As RasterConvertOptions = New RasterConvertOptions() 
 
   convertOptions.Source = sourceBinaryData 
   convertOptions.Destination = Nothing 
   convertOptions.Format = RasterImageFormat.Bmp 
   convertOptions.FirstPage = 1 
   convertOptions.LastPage = 1 
   convertOptions.BitsPerPixel = 24 
   convertOptions.QualityFactor = 2 
 
   Dim request As HistogramEqualizeRequest = New HistogramEqualizeRequest() 
 
   request.ConvertOptions = convertOptions 
   request.RegionData = Nothing 
   request.Type = HistogramEqualizeType.Yuv 
 
   Dim response As CommandResponse = client.HistogramEqualize(request) 
   If Not response.Destination Is Nothing Then 
      If TypeOf response.Destination Is RawBinaryData Then 
         File.WriteAllBytes(Path.Combine(LEAD_VARS.ImagesDir, "HistogramEqualize.bmp"), (TryCast(response.Destination, RawBinaryData)).Data) 
      End If 
   End If 
 
   client.Close() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class 

Requirements

Target Platforms

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