The JoomGallery (component) already has a built-in search function. You can find the associated settings in the configuration manager in the 'Search' tab.
 

The 'JoomSearchPlugin' plugin

This plugin is used to make more precise settings to search and to integrate in Joomla!. This will also search for the JoomGallery, for example if you use the 'Search' module of Joomla! on your website. After the installation you will find it under the name 'Search - JoomGallery' in the plugin manager of Joomla!

This plugin offers you three tabs for the configuration.

- Plugin
- Additional options for search mode 'Images'
- Additional options for search mode 'Categories'

If you move the mouse over the field name, more detailed explanations of the respective option appears.
 
The 'JoomSearchModule' module

This module offers the user numerous possibilities to influence the search. In this way you can set exactly which search options should be displayed to the user.
Important: In order to use the module, the 'JoomSearchPlugin' must also be installed and activated.

Note: Currently the search only works with the 'Search' component of Joomla!
Support for the 'Smart Search' (com_finder) is currently in progress.