Check http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.image(v=vs.110).aspx for the Image control in Asp.Net
At first I thought you could assign a bitmap image to the control, try to find that first (I couldn't find it immediately.)
Next are the subproblems you need to solve.
1. get the image from the database.
You'll need to get the database value into a
bitmap [
^]or
Image [
^]object. If you receive the resultset, the object containing the image is a byte array (byte []). Look at the
Stream[
^] class.
2. Once you have an image you can assign it to the control (if you can find that option) or alternatively you can write it to a temp folder and provide the uri to the Image control or write an HTML img tag. In the latter case you can just convert the resultset object directly to stream and write to file. The trouble with this second method is you need to find a way to also delete the created resources for example on session end.
I would create a small prototype and try step by step beginning by getting the byte array from the resultset and converting it A to a stream (write to file and check in windows explorer) and B to an Image or Bitmap object. Secondly try to convert that image to a control that can be shown on a web page. If that doesn't work, write to file and dynamically provide link in the web page. Thirdly, in the session end event cleanup the generated files. (The session object is still known at that point so you can keep the generated filenames in the session object. Beware of naming collisions when working with multiple files for multiple users...
Hope this helps.