.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;
        }