Gamma

This algorithm performs gamma correction of specified image in RGB color space.

   

• C#
• VB.Net

									Public Shared Sub ApplyGamma(ByRef bmp As Bitmap, redComponent As Double, greenComponent As Double, blueComponent As Double)
	If redComponent < 0.2 OrElse redComponent > 5 Then Return
	If greenComponent < 0.2 OrElse greenComponent > 5 Then Return
	If blueComponent < 0.2 OrElse blueComponent > 5 Then Return

	Dim bmpData As BitmapData = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb)
	Dim ptr As IntPtr = bmpData.Scan0
	Dim stopAddress As Integer = CInt(ptr) + bmpData.Stride * bmpData.Height

	While CInt(ptr) <> stopAddress
		Marshal.WriteByte(ptr, CByte(Math.Min(255, CInt(Math.Truncate((255.0 * Math.Pow(Marshal.ReadByte(ptr) / 255.0, 1.0 / blueComponent)) + 0.5)))))
		Marshal.WriteByte(ptr + 1, CByte(Math.Min(255, CInt(Math.Truncate((255.0 * Math.Pow(Marshal.ReadByte(ptr + 1) / 255.0, 1.0 / greenComponent)) + 0.5)))))
		Marshal.WriteByte(ptr + 2, CByte(Math.Min(255, CInt(Math.Truncate((255.0 * Math.Pow(Marshal.ReadByte(ptr + 2) / 255.0, 1.0 / redComponent)) + 0.5)))))

		ptr += 3
	End While

	bmp.UnlockBits(bmpData)
End Sub
								

Example

									DIm b As Bitmap = CType(Image.FromFile("rose.jpg"), Bitmap)
ApplyGamma(b, 2, 1.6, 0.8)