hi,
could someone help mee display a image preview, using
template_preview(id, show_buttons=True, parent=None, slot=None).
i have no idea how to create an id object from a png image…
A possibility: give a plane a texture: your image.
Even more easy: there is an addon: load an image as plane 
Ctrl-Alt-U ==> addons type in the search line: image and you should find it
then file -> import -> the addon should be chosen, etc.