We use categories to organize different kind of images, http://aspimagegallery.com/demo/Explorer-Layout.asp, in this layout, it will display all categories, when you click one category, it will only display  images of this category.   In slide show layout, it will list all images of all categories, if you want to customize it, you can update file "aspgallery\resources\Layout\SlideShow\Code.js" which can be found in download package.

 

Regards,

Eric