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PaintGamma Property
See Also  Example
Leadtools Namespace > RasterImage Class : PaintGamma Property



Gets or sets the current gamma correction value for the image.

Syntax

Visual Basic (Declaration)  
Public Property PaintGamma As Integer
Visual Basic (Usage) Copy Code
Dim instance As RasterImage
Dim value As Integer
 
instance.PaintGamma = value
 
value = instance.PaintGamma
C#  
public int PaintGamma {get; set;}
C++/CLI  
public:
property int PaintGamma {
   int get();
   void set (int value);
}

Return Value

The current gamma correction value.

Example

Visual Basic Copy Code
Public Sub IntensityExample()
   Dim f As IntensityForm = New IntensityForm()
   f.ShowDialog()
End Sub

Private Class IntensityForm : Inherits Form
   Private viewer As RasterImageViewer
   Private gammaTrackBar As TrackBar
   Private contrastTrackBar As TrackBar
   Private intensityTrackBar As TrackBar

   Public Sub New()
      ' Create the controls
      Size = New Size(800, 600)
      Dim controlsPanel As Panel = New Panel()
      controlsPanel.Size = New Size(400, 0)
      controlsPanel.BorderStyle = BorderStyle.Fixed3D
      controlsPanel.Dock = DockStyle.Left

      Dim labelLeft As Integer = 8
      Dim y As Integer = 16
      Dim trackBarLeft As Integer = 100

      Dim gammaLabel As Label = New Label()
      gammaLabel.Text = "Gamma:"
      gammaLabel.Location = New Point(labelLeft, y)
      gammaLabel.AutoSize = True
      controlsPanel.Controls.Add(gammaLabel)

      gammaTrackBar = New TrackBar()
      gammaTrackBar.Minimum = 1
      gammaTrackBar.Maximum = 100
      gammaTrackBar.TickFrequency = (gammaTrackBar.Maximum - gammaTrackBar.Minimum) \ 10
      gammaTrackBar.Location = New Point(trackBarLeft, y)
      gammaTrackBar.Width = 200
      AddHandler gammaTrackBar.Scroll, AddressOf gammaTrackBar_Scroll
      controlsPanel.Controls.Add(gammaTrackBar)
      gammaLabel.Top = gammaTrackBar.Top + (gammaTrackBar.Height - gammaLabel.Height) \ 2
      y = gammaTrackBar.Bottom + 8

      Dim contrastLabel As Label = New Label()
      contrastLabel.Text = "Contrast:"
      contrastLabel.Location = New Point(labelLeft, y)
      contrastLabel.AutoSize = True
      controlsPanel.Controls.Add(contrastLabel)

      contrastTrackBar = New TrackBar()
      contrastTrackBar.Minimum = -1000
      contrastTrackBar.Maximum = 1000
      contrastTrackBar.TickFrequency = (contrastTrackBar.Maximum - contrastTrackBar.Minimum) \ 10
      contrastTrackBar.Location = New Point(trackBarLeft, y)
      contrastTrackBar.Width = 200
      AddHandler contrastTrackBar.Scroll, AddressOf contrastTrackBar_Scroll
      controlsPanel.Controls.Add(contrastTrackBar)
      contrastLabel.Top = contrastTrackBar.Top + (contrastTrackBar.Height - contrastLabel.Height) \ 2
      y = contrastTrackBar.Bottom + 8

      Dim intensityLabel As Label = New Label()
      intensityLabel.Text = "Intensity:"
      intensityLabel.Location = New Point(labelLeft, y)
      intensityLabel.AutoSize = True
      controlsPanel.Controls.Add(intensityLabel)
      y = intensityLabel.Bottom + 8

      intensityTrackBar = New TrackBar()
      intensityTrackBar.Minimum = -1000
      intensityTrackBar.Maximum = 1000
      intensityTrackBar.TickFrequency = (intensityTrackBar.Maximum - intensityTrackBar.Minimum) \ 10
      intensityTrackBar.Location = New Point(trackBarLeft, y)
      intensityTrackBar.Width = 200
      AddHandler intensityTrackBar.Scroll, AddressOf intensityTrackBar_Scroll
      controlsPanel.Controls.Add(intensityTrackBar)
      intensityLabel.Top = intensityTrackBar.Top + (intensityTrackBar.Height - intensityLabel.Height) \ 2
      y = intensityTrackBar.Bottom + 8

      Dim defaultButton As Button = New Button()
      defaultButton.Text = "Default"
      defaultButton.Location = New Point(labelLeft, y)
      AddHandler defaultButton.Click, AddressOf defaultButton_Click
      controlsPanel.Controls.Add(defaultButton)

      Controls.Add(controlsPanel)

      viewer = New RasterImageViewer()
      viewer.Dock = DockStyle.Fill
      Controls.Add(viewer)
      viewer.SizeMode = RasterPaintSizeMode.Fit
      viewer.BringToFront()

      ' Load the image
      RasterCodecs.Startup()
      Dim codecs As RasterCodecs = New RasterCodecs()

      Dim srcFileName As String = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.cmp"
      viewer.Image = codecs.Load(srcFileName)

      codecs.Dispose()
      RasterCodecs.Shutdown()

      gammaTrackBar.Value = viewer.Image.PaintGamma
      contrastTrackBar.Value = viewer.Image.PaintContrast
      intensityTrackBar.Value = viewer.Image.PaintIntensity
      UpdateValues()
   End Sub

   Private Sub UpdateValues()
      Dim str As String = String.Format("Gamma = {0}, Contrast = {1}, Intensity = {2}", viewer.Image.PaintGamma, viewer.Image.PaintContrast, viewer.Image.PaintIntensity)
      Text = str
   End Sub

   Private Sub gammaTrackBar_Scroll(ByVal sender As Object, ByVal e As EventArgs)
      Dim tb As TrackBar = CType(IIf(TypeOf sender Is TrackBar, sender, Nothing), TrackBar)
      viewer.Image.PaintGamma = tb.Value
      UpdateValues()
   End Sub

   Private Sub contrastTrackBar_Scroll(ByVal sender As Object, ByVal e As EventArgs)
      Dim tb As TrackBar = CType(IIf(TypeOf sender Is TrackBar, sender, Nothing), TrackBar)
      viewer.Image.PaintContrast = tb.Value
      UpdateValues()
   End Sub

   Private Sub intensityTrackBar_Scroll(ByVal sender As Object, ByVal e As EventArgs)
      Dim tb As TrackBar = CType(IIf(TypeOf sender Is TrackBar, sender, Nothing), TrackBar)
      viewer.Image.PaintIntensity = tb.Value
      UpdateValues()
   End Sub

   Private Sub defaultButton_Click(ByVal sender As Object, ByVal e As EventArgs)
      viewer.Image.PaintGamma = 100
      viewer.Image.PaintIntensity = 0
      viewer.Image.PaintContrast = 0

      gammaTrackBar.Value = viewer.Image.PaintGamma
      contrastTrackBar.Value = viewer.Image.PaintContrast
      intensityTrackBar.Value = viewer.Image.PaintIntensity

      UpdateValues()
   End Sub
End Class
C# Copy Code
public void IntensityExample() 
{ 
   IntensityForm f = new IntensityForm(); 
   f.ShowDialog(); 
} 
class IntensityForm : Form 
{ 
   RasterImageViewer viewer; 
   TrackBar gammaTrackBar; 
   TrackBar contrastTrackBar; 
   TrackBar intensityTrackBar; 
 
   public IntensityForm() 
   { 
      // Create the controls 
      Size = new Size(800, 600); 
      Panel controlsPanel = new Panel(); 
      controlsPanel.Size = new Size(400, 0); 
      controlsPanel.BorderStyle = BorderStyle.Fixed3D; 
      controlsPanel.Dock = DockStyle.Left; 
 
      int labelLeft = 8; 
      int y = 16; 
      int trackBarLeft = 100; 
 
      Label gammaLabel = new Label(); 
      gammaLabel.Text = "Gamma:"; 
      gammaLabel.Location = new Point(labelLeft, y); 
      gammaLabel.AutoSize = true; 
      controlsPanel.Controls.Add(gammaLabel); 
 
      gammaTrackBar = new TrackBar(); 
      gammaTrackBar.Minimum = 1; 
      gammaTrackBar.Maximum = 100; 
      gammaTrackBar.TickFrequency = (gammaTrackBar.Maximum - gammaTrackBar.Minimum) / 10; 
      gammaTrackBar.Location = new Point(trackBarLeft, y); 
      gammaTrackBar.Width = 200; 
      gammaTrackBar.Scroll += new EventHandler(gammaTrackBar_Scroll); 
      controlsPanel.Controls.Add(gammaTrackBar); 
      gammaLabel.Top = gammaTrackBar.Top + (gammaTrackBar.Height - gammaLabel.Height) / 2; 
      y = gammaTrackBar.Bottom + 8; 
 
      Label contrastLabel = new Label(); 
      contrastLabel.Text = "Contrast:"; 
      contrastLabel.Location = new Point(labelLeft, y); 
      contrastLabel.AutoSize = true; 
      controlsPanel.Controls.Add(contrastLabel); 
 
      contrastTrackBar = new TrackBar(); 
      contrastTrackBar.Minimum = -1000; 
      contrastTrackBar.Maximum = 1000; 
      contrastTrackBar.TickFrequency = (contrastTrackBar.Maximum - contrastTrackBar.Minimum) / 10; 
      contrastTrackBar.Location = new Point(trackBarLeft, y); 
      contrastTrackBar.Width = 200; 
      contrastTrackBar.Scroll += new EventHandler(contrastTrackBar_Scroll); 
      controlsPanel.Controls.Add(contrastTrackBar); 
      contrastLabel.Top = contrastTrackBar.Top + (contrastTrackBar.Height - contrastLabel.Height) / 2; 
      y = contrastTrackBar.Bottom + 8; 
 
      Label intensityLabel = new Label(); 
      intensityLabel.Text = "Intensity:"; 
      intensityLabel.Location = new Point(labelLeft, y); 
      intensityLabel.AutoSize = true; 
      controlsPanel.Controls.Add(intensityLabel); 
      y = intensityLabel.Bottom + 8; 
 
      intensityTrackBar = new TrackBar(); 
      intensityTrackBar.Minimum = -1000; 
      intensityTrackBar.Maximum = 1000; 
      intensityTrackBar.TickFrequency = (intensityTrackBar.Maximum - intensityTrackBar.Minimum) / 10; 
      intensityTrackBar.Location = new Point(trackBarLeft, y); 
      intensityTrackBar.Width = 200; 
      intensityTrackBar.Scroll += new EventHandler(intensityTrackBar_Scroll); 
      controlsPanel.Controls.Add(intensityTrackBar); 
      intensityLabel.Top = intensityTrackBar.Top + (intensityTrackBar.Height - intensityLabel.Height) / 2; 
      y = intensityTrackBar.Bottom + 8; 
 
      Button defaultButton = new Button(); 
      defaultButton.Text = "Default"; 
      defaultButton.Location = new Point(labelLeft, y); 
      defaultButton.Click += new EventHandler(defaultButton_Click); 
      controlsPanel.Controls.Add(defaultButton); 
 
      Controls.Add(controlsPanel); 
 
      viewer = new RasterImageViewer(); 
      viewer.Dock = DockStyle.Fill; 
      Controls.Add(viewer); 
      viewer.SizeMode = RasterPaintSizeMode.Fit; 
      viewer.BringToFront(); 
 
      // Load the image 
      RasterCodecs.Startup(); 
      RasterCodecs codecs = new RasterCodecs(); 
 
      string srcFileName = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.cmp"; 
      viewer.Image = codecs.Load(srcFileName); 
 
      codecs.Dispose(); 
      RasterCodecs.Shutdown(); 
 
      gammaTrackBar.Value = viewer.Image.PaintGamma; 
      contrastTrackBar.Value = viewer.Image.PaintContrast; 
      intensityTrackBar.Value = viewer.Image.PaintIntensity; 
      UpdateValues(); 
   } 
 
   void UpdateValues() 
   { 
      string str = string.Format( 
         "Gamma = {0}, Contrast = {1}, Intensity = {2}", 
         viewer.Image.PaintGamma, viewer.Image.PaintContrast, viewer.Image.PaintIntensity); 
      Text = str; 
   } 
 
   void gammaTrackBar_Scroll(object sender, EventArgs e) 
   { 
      TrackBar tb = sender as TrackBar; 
      viewer.Image.PaintGamma = tb.Value; 
      UpdateValues(); 
   } 
 
   void contrastTrackBar_Scroll(object sender, EventArgs e) 
   { 
      TrackBar tb = sender as TrackBar; 
      viewer.Image.PaintContrast = tb.Value; 
      UpdateValues(); 
   } 
 
   void intensityTrackBar_Scroll(object sender, EventArgs e) 
   { 
      TrackBar tb = sender as TrackBar; 
      viewer.Image.PaintIntensity = tb.Value; 
      UpdateValues(); 
   } 
 
   void defaultButton_Click(object sender, EventArgs e) 
   { 
      viewer.Image.PaintGamma = 100; 
      viewer.Image.PaintIntensity = 0; 
      viewer.Image.PaintContrast = 0; 
 
      gammaTrackBar.Value = viewer.Image.PaintGamma; 
      contrastTrackBar.Value = viewer.Image.PaintContrast; 
      intensityTrackBar.Value = viewer.Image.PaintIntensity; 
 
      UpdateValues(); 
   } 
}

Remarks

The paint gamma value can be any number greater than 0. The default value is 100.

Because this is an unsigned integer, it is 100 times the actual gamma value. For example, use 235 to set a gamma value of 2.35. Intensity values ideally follow a logarithmic progression, because the eye perceives changes in intensity as being equal when the ratio of change is equal. For example, we would see a change from 0.1 to 0.2 as being equal to a change from 0.2 to 0.4.

Gamma is a standard constant that is used to calculate the progression. For most CRTs the gamma constant is in the range of 2.2 to 2.5.

For more information, refer to Changing Brightness and Contrast.

Requirements

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

See Also