Well yes and no
PhotoPost PHP Photo Sharing Photo Gallery Installation Guide
Our install directions need to be followed to the tee for proper operation so yes the data and uploads directories need to be 777 at every level as noted.
Only very few servers could do 755 and work properly but that requires some work by the host which most hosts dont do so for 99.9% of peoples servers 777 is what it has to be. I am sure you probally say upload issues as well with improper permissions set as well.