.net图片快速去底（去除白色背景）

 public System.Drawing.Bitmap KnockOutGzf(String path)

        {

            System.Drawing.Image image = System.Drawing.Image.FromFile(path);

            System.Drawing.Bitmap bitmapProxy = new System.Drawing.Bitmap(image);

            image.Dispose();

            for (int i = 0; i < bitmapProxy.Width; i++)

            {

                for (int j = 0; j < bitmapProxy.Height; j++)

                {

                    System.Drawing.Color c = bitmapProxy.GetPixel(i, j);

                    if (!(c.R < 240 || c.G < 240 || c.B < 240))

                    {

                        bitmapProxy.SetPixel(i, j, System.Drawing.Color.Transparent);

                    }

                }

            }

            return bitmapProxy;

        }