How to hide the path of the image files in my ASP site?

Hi,

I hope this is not too difficult:

How to hide the path of the image files in my ASP site (ASP.Net code also works)?
Now, a visitor can see the path of the image related to an article something like
http://www.....com/images/...image1.jpg
I do like visitors to see or download that image when he read the article. However, a visitor has tried to download all the image files in the folder!

Thanks a lot for your help!