This gallery has a component, module and plug in to do everything I needed to display >100 paintings in a variety of formats. Images are organized in categories with tags and descriptions that are searchable, results can be displayed as a gallery. Display is controlled by profiles, assign a profile to a gallery to control how it is displayed. Can use a Module to make a slide show. Has watermark function.
I've been working with Joomla for >5 years, but I think it is pretty easy to use even with less experience.