There's a true morphing application for photos called
Norrkross MorphX. You add two photos taken at different times, index a couple of fixed pointed on each photo, like the eyes, and it will create a morph QT movie. Here's an example of my son titled
"From Cheerios to Corona". (Disclaimer: He didn't get his taste in beer from me)
This would be more effort that a slideshow with the dissolve transition which Terence mentioned. A log would depend on how uniform the photos were as far as the positioning of the subject, etc.
OT