: image {
   action alignment aspect_ratio color 
   fixed_height fixed_width height is_enabled 
   is_tab_stop key mnemonic value width 

An image is a rectangle in which a vector graphic picture is displayed. Images are used to display icons, linetypes, text fonts, and color patches in AutoCAD dialog boxes. See Creating Images for instructions on how to generate images for image tiles.

You must assign an image tile either an explicit width and height attribute, or one of those attributes plus an aspect_ratio.