How to display Item Image in tooltip

[deogo]

Hey guys, help needed
I'd like to display a bigger item image in tooltip, but can't figure the proper code
the string #UID: .. <UID> .. ":0" seems always create a text-sized images (it's used in tooltip name by default)

i've found a lot of :display, :toScreen and :toScreenFull functions but have no idea how to use them for item tooltip
the self.image for item seems contains some data
i'd like to add item image in
\mod\class\Object.lua:getDesc