This is a internet question (I assume) and probably should be dealt with in the GoLive forum, if you are using that program, or the Web Design forum if you are not.
This is not something that Photoshop or ImageReady can do.
Don
In what viewing environment? Are you talking about on a web page?
Laki,
The Firefox browser does exactly that by default when an image is larger than the browser viewport;
but opening a larger image is nothing to do with the smaller image itself – that’s achieved with the HTML code associated with the image.
You could create action to insert a small magnifying glass image (snagged from a print-screen) into a thumbnail of your image.
I’ve seen a lot of those thumbnails with magnifiers in the Adobe photography forum and I suspect Pixeltran may have automated the "insert tiny magnifier in thumnail" process.
-Mike
Your action might go something like this:
<— start –>
File> automate> Fit Image> (Size 50px x 50 px)
Open new image (your tiny magnifying glass).
Select all>
Copy.
Close (Tiny magnifying glass)image> (no save.)
Select (your 50×50 thumbnail) image.
Paste.
Move Tiny magnifying glass to bottom corner.
Resize as needed.
Save for web> (don’t change image name) to (use a new:) thumbnails folder. Close image (without saving.)
<—-end —–>