Image scaling and other formatting within handbook pages

I haven't found documentation on the format of handbook pages. I've been able to figure out most of what I need, such as node references, keyboard elements, etc., but I don't see if there's a way to scale images to make them fit in a compact space.

I realize I can create a small 300x400 pixel image, or whatever, but I'd rather use a higher resolution image if that's possible. Most people have high-res monitors today and we might as well use images with visible fine features. The [ inline:... ] element just seems to plunk in whatever has been uploaded using its absolute resolution to determine the display size.

Thanks if anyone can show me what I'm missing. If there's a reference to handbook source format that would be a plus.