ie has the rasterring selction of images

# = blue marked
_ = transperent

_#_#_#
#_#_#_#
_#_#_#_
#_#_#_#

so you start with to images aplling a pattern (you need to diffrend)

patern one: (the one that will be for the image that dissapears):

for # use a color for “_” use nothing (transparent)

_#
#_

patern to for the image that will apear is the same reverse:
#_
_#