Increases or decreases the contrast of the image, using a histogram to determine the median brightness. Supported in Silverlight, Windows Phone 7

Object Model

Syntax

Visual Basic (Declaration)
Public Class HistogramContrastCommand Inherits Leadtools.ImageProcessing.RasterCommand Implements IRasterCommand

Visual Basic (Usage)	Copy Code
Dim instance As HistogramContrastCommand

C#
public class HistogramContrastCommand : Leadtools.ImageProcessing.RasterCommand, IRasterCommand

C++/CLI
public ref class HistogramContrastCommand : public Leadtools.ImageProcessing.RasterCommand, IRasterCommand

Example

Run the Leadtools.ImageProcessing.Color.HistogramContrastCommand on an image and increase its contrast.

Visual Basic	Copy Code
Public Sub HistogramContrastCommandExample() Dim codecs As New RasterCodecs() codecs.ThrowExceptionsOnInvalidImages = True Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Master.jpg")) ' Prepare the command Dim command As HistogramContrastCommand = New HistogramContrastCommand 'Increase the contrast using the histogram by 25 percent of the possible range. command.Contrast = 250 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

Visual Basic

Copy Code

Public Sub HistogramContrastCommandExample()
   Dim codecs As New RasterCodecs()
   codecs.ThrowExceptionsOnInvalidImages = True

   Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Master.jpg"))

   ' Prepare the command
   Dim command As HistogramContrastCommand = New HistogramContrastCommand
   'Increase the contrast using the histogram by 25 percent of the possible range.
   command.Contrast = 250

   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

C#	Copy Code
public void HistogramContrastCommandExample() { // Load an image RasterCodecs codecs = new RasterCodecs(); codecs.ThrowExceptionsOnInvalidImages = true; RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Master.jpg")); // Prepare the command HistogramContrastCommand command = new HistogramContrastCommand(); //Increase the contrast using the histogram by 25 percent of the possible range. command.Contrast = 250; 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"; }

Copy Code

public void HistogramContrastCommandExample()
   {
      // Load an image
      RasterCodecs codecs = new RasterCodecs();
      codecs.ThrowExceptionsOnInvalidImages = true;

      RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Master.jpg"));

      // Prepare the command
      HistogramContrastCommand command = new HistogramContrastCommand();
      //Increase the contrast using the histogram by 25 percent of the possible range.
      command.Contrast = 250;
      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";
}

SilverlightCSharp	Copy Code
public void HistogramContrastCommandExample(RasterImage image, Stream outStream) { // Prepare the command HistogramContrastCommand command = new HistogramContrastCommand(); //Increase the contrast using the histogram by 25 percent of the possible range. command.Contrast = 250; command.Run(image); // Save result image RasterCodecs codecs = new RasterCodecs(); codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24); image.Dispose(); }

SilverlightCSharp

Copy Code

public void HistogramContrastCommandExample(RasterImage image, Stream outStream)
{
   // Prepare the command
   HistogramContrastCommand command = new HistogramContrastCommand();
   //Increase the contrast using the histogram by 25 percent of the possible range.
   command.Contrast = 250;
   command.Run(image);
   // Save result image
   RasterCodecs codecs = new RasterCodecs();
   codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24);
   image.Dispose();
}

SilverlightVB	Copy Code
Public Sub HistogramContrastCommandExample(ByVal image As RasterImage, ByVal outStream As Stream) ' Prepare the command Dim command As HistogramContrastCommand = New HistogramContrastCommand() 'Increase the contrast using the histogram by 25 percent of the possible range. command.Contrast = 250 command.Run(image) ' Save result image Dim codecs As RasterCodecs = New RasterCodecs() codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24) image.Dispose() End Sub

SilverlightVB

Copy Code

Public Sub HistogramContrastCommandExample(ByVal image As RasterImage, ByVal outStream As Stream)
   ' Prepare the command
   Dim command As HistogramContrastCommand = New HistogramContrastCommand()
   'Increase the contrast using the histogram by 25 percent of the possible range.
   command.Contrast = 250
   command.Run(image)
   ' Save result image
   Dim codecs As RasterCodecs = New RasterCodecs()
   codecs.Save(image, outStream, RasterImageFormat.Jpeg, 24)
   image.Dispose()
End Sub

Remarks

This class finds the median brightness of the image, then brightens the pixels with values above the median and darkens the pixels with values below the median. This is more sophisticated (but slower) than the Leadtools.ImageProcessing.Color.ChangeContrastCommand, which uses the middle possible value (128) rather than finding the actual median.
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.

For more information, refer to Changing Brightness and Contrast.

If the image has a LUT and you want to work on the image data, set RasterImage.UseLookupTable to false. Then, after calling the method, reset the UselookupTable property to true, as follows:

            rasterImage.UseLookupTable = false;
            Method(rasterImage);
            
            rasterImage.UseLookupTable = true;

Inheritance Hierarchy

System.Object
Leadtools.ImageProcessing.RasterCommand
Leadtools.ImageProcessing.Color.HistogramContrastCommand

Requirements

Target Platforms: Silverlight, Windows XP, Windows Server 2003 family, Windows Server 2008 family, Windows Vista, Windows 7, MAC OS/X (Intel Only)

LEADTOOLS Image Processing (Leadtools.ImageProcessing.Color assembly)	Send comments on this topic. \| Back to Introduction - All Topics \| Help Version 17.0.3.29
HistogramContrastCommand Class
See Also Members

Object Model

Syntax

Example

Remarks

Inheritance Hierarchy

Requirements

See Also

Reference