Website that uses iPhoto or Photos library as the database
Have you considered using iCloud Photo Sharing? 

This can be used to share specific photo albums, so you could create one for each of the four categories. You can also share these as a public website so that people who aren't part of Apple's ecosystem can also view them.

For more information refer to: iCloud Photo Sharing.

NOTE: One limitation you should be aware of is that currently iCloud Photo Sharing limits you to sharing no more than 5,000 photos/videos.