1 Bitmap bmp = new Bitmap(pictureBox1.Image, pictureBox1.Image.Size);
2 BitmapData data = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, bmp.PixelFormat);
3 int length = data.Stride * data.Height;
4 IntPtr ptr = data.Scan0;
5 byte[] buff = new byte[length];
6 Marshal.Copy(ptr, buff, 0, length);
7 for (int i = 3; i < length; i += 4)
8 {
9 if (buff[i - 1] >= 230 && buff[i - 2] >= 230 && buff[i - 3] >= 230)
10 {
11 buff[i] = 0;
12 }
13 }
14 Marshal.Copy(buff, 0, ptr, length);
15 bmp.UnlockBits(data);