The first 15 pop-up windows are automatically resized when loaded.  This posting explains how it is done. 

The technique has been amended so that the pop-up window is loaded from a thumbnail image, is anchored top-left and automatically unloads after 10 seconds

Copy and paste this code into a new page (in html view) and save the page as popup.htm

Copy and paste this code into the head section of any page which requires pop-up images

Ensure you have a thumbnail of the image to be used in the pop-up. DO NOT use the auto-thumbnail feature Why ?

Insert the thumbnail at the required position on the page. Select it and click on the hyperlink button in the standard toolbar.

In the URL enter:   javascript:PopupPic( 'yourpic.jpg' )     [leave target frame as Page Default]

Now go to HTML view and change img border from "0" to "1"

    <a href="javascript:PopupPic('yourpic.jpg')"><img border="1" src="yourpic_small.jpg" width="100" height="162"></a>