Deserializing byte to image from sql through memory stream - sql-server

Question

I have convert an image to be saved in SQL Server Database as Binary with column name as "img". I have PictureBox1 ready to show the image.
Now I want to import the binary data back into image, and I'm trying this code in VB.net for example:
Dim queries As String
queries = "SELECT * from StudentData where Std_fname='" & ComboBox1.Text & "'"
Dim com As New SqlCommand(queries, sqlconn)
sqlconn.Open()
Dim ds As New SqlDataAdapter(queries, sqlconn)
Dim dr As SqlDataReader
dr = com.ExecuteReader()
While dr.Read
Std_fnameTextBox.Text = dr("Std_fname")
Std_lnameTextBox.Text = dr("Std_lname")
AgeTextBox.Text = dr("age")
AddressTextBox.Text = dr("address")
StateTextBox.Text = dr("state")
CityTextBox.Text = dr("city")
CountryTextBox.Text = dr("country")
Ic_passportTextBox.Text = dr("ic_passport")
DobDateTimePicker.Text = dr("dob")
PictureBox1.Image = dr("img") 'Here is the problem. If I run it, it ask me to convert Binary to Image first.
End While
sqlconn.Close()
The problem is, I don't know how to convert binary to image in this situation. And yes, I've been googling for it, but can't seem to get the right answer.

Answer 1

dr("img") returns either DBNull.Value, or a byte[]. You can use the stream overload of the Bitmap constructor to load this. In C# (should be easy to translate to VB), you can do it like this:
var imageData = (byte[])dr["img"];
using (var ms = new MemoryStream(imageData))
{
var bmp = new Bitmap(ms);
// Work with bmp
}
As Mark correctly noted, you're supposed to keep the stream open for the whole life-time of the Bitmap - this is actually a bit trickier than it seems, because the Bitmap doesn't even keep a reference to the stream.
The easiest way to handle this is to clone the bitmap after you create it, to remove the dependency on the stream. Unless you can do whatever work you need to do within the using - unlikely if you want to display it in a PictureBox.
You can also use ImageConverter.ConvertFrom directly, but all it does is create the MemoryStream if used on raw byte[] data :)