Multiple SessionIDs are created for the same visitor

[Mike Kansky]

i have a following tag in all of the HTML pages of my site:
<img src="http://domain.com/image.aspx">
In image.aspx i just send an image to the browser using simple
respone.redirec t("imagepath" ) and there is also some tracking code in
image.aspx
The weird thing is that a new Session.Session ID is created by image.aspx as
a visitor hits a new page of my site. I assume it is because <img> tag
generates an out-of-process request?

I have to force the image.aspx to create a session.session id on the first
page the visitor hits and retain it on all the following pages as the
visitor navigates the site. I need to do that because image.asp has logic
there that's based on visitor's sessionid.

Please, any ideas?