MemoryStream ms = new MemoryStream(bytes);
ms.Position = 0;
Image img = Image.FromStream(ms);
ms.Close();
this.pictureBox1.Image

System.Text.UnicodeEncoding converter = new System.Text.UnicodeEncoding();
　　byte[] inputBytes =converter.GetBytes(inputString);
　　string inputString = converter.GetString(inputBytes);

string inputString = System.Convert.ToBase64String(inputBytes);
　　byte[] inputBytes = System.Convert.FromBase64String(inputString);
FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);

public byte[] StreamToBytes(Stream stream)
{
    byte[] bytes = new byte[stream.Length];
    stream.Read(bytes, 0, bytes.Length);
    // 设置当前流的位置为流的开始
    stream.Seek(0, SeekOrigin.Begin);
    return bytes;
}

public Stream BytesToStream(byte[] bytes)
{
    Stream stream = new MemoryStream(bytes);
    return stream;
}

public void StreamToFile(Stream stream,string fileName)
{
    // 把 Stream 转换成 byte[]
    byte[] bytes = new byte[stream.Length];
    stream.Read(bytes, 0, bytes.Length);
    // 设置当前流的位置为流的开始
    stream.Seek(0, SeekOrigin.Begin);
    // 把 byte[] 写入文件
    FileStream fs = new FileStream(fileName, FileMode.Create);
    BinaryWriter bw = new BinaryWriter(fs);
    bw.Write(bytes);
    bw.Close();
    fs.Close();
}

public Stream FileToStream(string fileName)
{            
    // 打开文件
    FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
    // 读取文件的 byte[]
    byte[] bytes = new byte[fileStream.Length];
    fileStream.Read(bytes, 0, bytes.Length);
    fileStream.Close();
    // 把 byte[] 转换成 Stream
    Stream stream = new MemoryStream(bytes);
    return stream;
}