Image into string and back

Question

I need to store images into an MSSQL database as part of a form processing which is handled by PHP.

Before that, my client did this task with following C# code:

  Dim content As Byte() = ImageToStream(fName)
                cnn.Open()

                Dim cmd As New SqlCommand("UPDATE lide SET pictPostava = @img WHERE ID = '" & GetValueToTextBox(iRow, "ID") & "'", cnn)
                cmd.Parameters.AddWithValue("@img", content)
                cmd.ExecuteNonQuery()

                cnn.Close()

                content = Nothing
    Public Function ImageToStream(ByVal fileName As String) As Byte()
        Dim stream As New MemoryStream()
tryagain:
        Try
            Dim image As New Bitmap(fileName)
            image.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg)
        Catch ex As Exception
            GoTo tryagain
        End Try

        Return stream.ToArray()
    End Function

I tried to replicate it via unpack() function based on http://php.net/manual/en/function.mssql-query.php#31688

// convert file
$file = file_get_contents('http://www.sunagency.cz/wp-content/uploads/2017/01/1745083-150x150.jpg');
$unpacked = "0x" . unpack("H*hex", $file);

// get the hexcode of image
print_r( $unpacked['hex'] );

However, he can't restore it. And to be honest, I'm not sure how to revert it back with PHP either - changing header into Image doesn't solve the problem.

// view the packed file
header("Content-type: image/jpeg;");
echo $unpacked['hex'];

Could you help? I have never done this before and would be more than happy to solve the problem.