I have seen this particular effect in various places - it is used a lot on wikipedia - where you click on an image and get a large version of the image that fills the browser window. When you hover over the larger image, the cursor becomes a magnifying glass that allows you to click and zoom to 100% and back to "fill window" size.

What I think is happening is that the image link just goes to the large version of the image itself (as opposed to another html page), as in
<a href="xyz.jpg">
and the browser is handling the hover/zoom effects. I am using Safari and Firefox on a mac and currently don't have access to windows, but I am assuming it works on ie and other browsers this way as well - can anyone confirm this? Is there anything special about how this is done, or is it a simple link to a standard jpeg image file?

Can it be counted on to be standard behavior for most browsers?

Are there other common ways this is achieved?

The reason I am asking this is that I have a client that is requesting this behavior on a site I am making. One of their requests is that the "fill-window-sized" view of the image not be left aligned in the screen, but rather centered (safari and ff left align it if the window is of a shorter aspect ratio than the image). They may want other customization as well, such as a caption.

I don't think this behavior can be customized without some somewhat involved css/js work. Or are there any coding techniques that can can easily modify these behaviors - as opposed to coding a solution from scratch?

Or are there any libraries or solutions for customizing this (I am aware of various js overlay box solutions, but this is not what they want - they want the image to open in a new browser window, filling the window with the zoom cursor).

The "open in new window" thing is another issue I have questions about, but as it is a separate issue and this post is already way too long, I will start a new thread. Thanx.