HistogramEqualize Method

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

Visual Basic
C#
Objective-C
Java
C++

[FaultContractAttribute(DetailType=Leadtools.Services.Raster.FaultContracts.RasterFault, 
   Action="", 
   Name="", 
   Namespace="", 
   ProtectionLevel=ProtectionLevel.None, 
   HasProtectionLevel=false)]
[OperationContractAttribute("HistogramEqualize")]
CommandResponse HistogramEqualize( 
   HistogramEqualizeRequest request
)

'Declaration
 
<FaultContractAttribute(DetailType=Leadtools.Services.Raster.FaultContracts.RasterFault, 
   Action="", 
   Name="", 
   Namespace="", 
   ProtectionLevel=ProtectionLevel.None, 
   HasProtectionLevel=False)>
<OperationContractAttribute("HistogramEqualize")>
Function HistogramEqualize( _
   ByVal request As HistogramEqualizeRequest _
) As CommandResponse

'Usage
 
Dim instance As IColorProcessingService
Dim request As HistogramEqualizeRequest
Dim value As CommandResponse
 
value = instance.HistogramEqualize(request)

[FaultContractAttribute(DetailType=Leadtools.Services.Raster.FaultContracts.RasterFault, 
   Action="", 
   Name="", 
   Namespace="", 
   ProtectionLevel=ProtectionLevel.None, 
   HasProtectionLevel=false)]
[OperationContractAttribute("HistogramEqualize")]
CommandResponse^ HistogramEqualize( 
   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

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Copy Code

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

using Leadtools.Services;
using leadtools.services.datacontracts._2009._01;
using leadtools.services.raster.datacontracts._2009._01;
using leadtools.services.imageprocessing.datacontracts._2009._01;

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";
}

Requirements

Target Platforms

Reference

IColorProcessingService Interface
IColorProcessingService Members