Color Substitution

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

   

• C#
• VB.Net

									public static void ApplyColorSubstitution(ref Bitmap bmp, int threshold, System.Drawing.Color sourceColor, System.Drawing.Color newColor)
{
	BitmapData bmpData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

	unsafe
	{
		byte* ptr = (byte*)bmpData.Scan0.ToPointer();
		int stopAddress = (int)ptr + bmpData.Stride * bmpData.Height;
		int SrcTotalRGB = sourceColor.R + sourceColor.G + sourceColor.B;
		int TotalRGB;

		while ((int)ptr != stopAddress)
		{
			TotalRGB = ptr[0] + ptr[1] + ptr[2];

			if (Math.Abs(SrcTotalRGB - TotalRGB) < threshold)
			{
				ptr[0] = newColor.B;
				ptr[1] = newColor.G;
				ptr[2] = newColor.R;
			}

			ptr += 3;
		}
	}

	bmp.UnlockBits(bmpData);
}
								

Example

									Bitmap b = (Bitmap)Image.FromFile("rose.jpg");
ApplyColorSubstitution(ref b, 50, Color.Green, Color.Blue);