public MainWindow()

        {

            InitializeComponent();

            byte[] b = GetPictureData(@"F:\WPF\TestSolution\TestReatByteFromDB\Images\123.png");

            BitmapImage myimg = ByteArrayToBitmapImage(b);

            this.testImg.Source = myimg;

        }

        public byte[] GetPictureData(string imagepath)

        {

            /**/

            ////根据图片文件的路径使用文件流打开，并保存为byte[]

            FileStream fs = new FileStream(imagepath, FileMode.Open);//可以是其他重载方法

            byte[] byData = new byte[fs.Length];

            fs.Read(byData, 0, byData.Length);

            fs.Close();

            return byData;

        }

        public BitmapImage ByteArrayToBitmapImage(byte[] byteArray)

        {

            BitmapImage bmp = null;

            try

            {

                bmp = new BitmapImage();

                bmp.BeginInit();

                bmp.StreamSource = new MemoryStream(byteArray);

                bmp.EndInit();

            }

            catch

            {

                bmp = null;

            }

            return bmp;

        }

        public byte[] BitmapImageToByteArray(BitmapImage bmp)

        {

            byte[] byteArray = null;

            try

            {

                Stream sMarket = bmp.StreamSource;

                if (sMarket != null && sMarket.Length > 0)

                {

                    //很重要，因为Position经常位于Stream的末尾，导致下面读取到的长度为0。

                    sMarket.Position = 0;

                    using (BinaryReader br = new BinaryReader(sMarket))

                    {

                        byteArray = br.ReadBytes((int)sMarket.Length);

                    }

                }

            }

            catch

            {

                //other exception handling

            }

            return byteArray;

        }