Color Substitution

This algorithm replaces the specified source color with the new color.

   

• C#
• VB.Net

									Public Shared Sub ApplyColorSubstitution(ByRef bmp As Bitmap, threshold As Integer, sourceColor As System.Drawing.Color, newColor As System.Drawing.Color)
	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
	Dim SrcTotalRGB As Integer = sourceColor.R + sourceColor.G + sourceColor.B
	Dim TotalRGB As Integer

	While CInt(ptr) <> stopAddress
		TotalRGB = CInt(Marshal.ReadByte(ptr)) + CInt(Marshal.ReadByte(ptr + 1)) + CInt(Marshal.ReadByte(ptr + 2))

		If Math.Abs(SrcTotalRGB - TotalRGB) < threshold Then
			Marshal.WriteByte(ptr, newColor.B)
			Marshal.WriteByte(ptr + 1, newColor.G)
			Marshal.WriteByte(ptr + 2, newColor.R)
		End If

		ptr += 3
	End While

	bmp.UnlockBits(bmpData)
End Sub
								

Example

									DIm b As Bitmap = CType(Image.FromFile("rose.jpg"), Bitmap)
ApplyColorSubstitution(b, 50, Color.Green, Color.Blue)