Opposite of “mental picture” [closed]

Question

Is there a good antonym to "mental picture"? For example:

"Remembering the Kana" uses mental pictures, but no physical pictures.

Answer 1

It depends on context but in this case 'imagery' could work well?

"Remembering the Kana" uses mental pictures, but no physical imagery."

Or something like

"The imagery used by "Remembering the Kana" is mental, rather than physical."