pinkpippy,
Another interpretation:
Zooming in and out only changes the view, but leaves all objects (including the image) as they are (no change of actual size(s)).
To scale the image uniformly/proportionally by a specific scaling factor, you may select it and then insert a % uniform scaling factor in Object>Transform>Scale (200% for twice the size etc), or you may multiply the W or H value in the Transform palette (add *2 for twice the size etc) and then Ctrl/CmdEnter to keep proportions (uniform scaling).
You may scale in other ways, too, both uniformly and non uniformly.
You can do any kind of scaling without zooming.