WPF怎么实现为图片去背景？我这两种方案错在哪了？请大神指点指点！！！！！

 #region 方法一：修改byte[]的颜色

            

            //将图片转成byte数组存入内存中，在数组中修改鼠标点击的颜色，  i:B   i+1:G  i+2:R  i+3:Alpha    颜色一致的话改为 R:0xff,B:0xff,G:0xff  Alpha:0

            BitmapData bmpData = bmp.LockBits(new System.Drawing.Rectangle(0, 0, bmp.Width, bmp.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, bmp.PixelFormat);



            byte[] maskImageRGBData = new byte[bmpData.Stride * bmpData.Height];



            System.Runtime.InteropServices.Marshal.Copy(bmpData.Scan0, maskImageRGBData, 0, maskImageRGBData.Length);



            //鼠标选中的当前颜色

            byte[] curColorBytes = new byte[3];

            //curColorBytes[0] = 0xff;

            //curColorBytes[1] = 0xff;

            //curColorBytes[2] = 0xff;

            //curColorBytes[3] = 0;

            curColorBytes[0] = currentColor.B;

            curColorBytes[1] = currentColor.G;

            curColorBytes[2] = currentColor.R;

        



            for (int j = 0; j + 2 < maskImageRGBData.Length; j += 4)

            {

                if(curColorBytes[0]==maskImageRGBData[j]&&curColorBytes[1]==maskImageRGBData[j+1]&&curColorBytes[2]==maskImageRGBData[j+2])

                {

                    maskImageRGBData[j] = 0xff;

                    maskImageRGBData[j+1] = 0xff;

                    maskImageRGBData[j+2] = 0xff;

                    maskImageRGBData[j+3] = 0;

                }

            }



            System.Runtime.InteropServices.Marshal.Copy(maskImageRGBData, 0, bmpData.Scan0, maskImageRGBData.Length);

            bmp.UnlockBits(bmpData);

            #endregion



            #region 方法二：直接修改该像素点的值   currentColor即为鼠标获取到的像素点



            if (bmp != null)

            {

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

                {

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

                    {

                        cur = bmp.GetPixel(i, j);

                        if (cur.Equals(currentColor))

                        {

                            bmp.SetPixel(i, j, System.Drawing.Color.FromArgb(0x00, 0xff, 0xff, 0xff));//System.Drawing.Color.Transparent); //

                            bmp.MakeTransparent(cur);

                        }

                    }

                }

            }

            #endregion

            bmp.Save("d://111.png");