private void DrawFastPixel(int x, int y, Color c)
 {
     unsafe {
         byte* ptr = (byte*) data.Scan0;
         ptr[(x * 3) + y * data.Stride    ] = c.B255();
         ptr[(x * 3) + y * data.Stride + 1] = c.G255();
         ptr[(x * 3) + y * data.Stride + 2] = c.R255();
     }
 }