A number of combined pictures.
At first, have a global look and determine what you see. Secondly, try to see/discover the details.
Bottom or top? Front or back?.
Feather or pageon?.
Global: old man and wife; detail: two gitar playing men.
Global: old man with artistic moustache and hair; detail: two (!) knights riding horses with windmill in background.
Other detail: do you see the many faces in the background??? Approximately 15 faces to discover!!!
Global: nice picture of nature; detail: 7 times heart visible...
Classic: what do you see? Young or old lady (both are in the picture!)
Also classic: duck or rabbit?
Global: old man pictured as a general; details: 9 persons to be discovered!
Global: anatomic face; details: 25 different animals!
A classic example. Global: skull; detail: two men around a table.
Variation of the previous picture. Global: skull; detail: man and wife.
Global: face of Jezus; detail: his crusifying.
Also notice other details: the wounds are also crusifyings etc.
One or more deer?
Global: a beautiful tiger. But where is the hidden tiger?
Detail: have a close watch at the stripes on the tiger. It reads "the hidden tiger".
Waterfall of monks.
Houses or audience?
Bridge or ships?
How many horses do you see?