For example, the image below is actually 1920x1200.
However, if you embed the same image in a Page, it is just truncated, not even resized.
You can test this on your own installs using this code:
<img src="http://files.myopera.com/white_demon/albums/886891/ice-age-scrat-wallpaper-hi-res.jpg" alt="Scrat" />
It would be nice if the same functionality existed in Pages with regards to automatic resizing and click to zoom.