The @image directive specifies an image to be displayed centered in large format on a page. So the code:

@image ../apple.jpg

displays a picture of an apple on this page.

The image filenames in the @icon, @image, @inset, and @gallery directives are relative to the page filename they're in, unless they start with a / in which case they're relative to the root of the website.

An enhancement is allowing options to be specified by appending ";..." to the end of the image filename. So appending ";top" to a filename will cause thumbnails to be taken from the top of the image rather than the middle.