This plugin lets you create an in-line gallery, on a WordPress Page, that consists of a grid of thumbnails and a larger viewing window. When the mouse hovers over a thumbnail – or clicks – the viewing window is filled with the full image. You can also set this to be a slideshow with full image transitions. The plugin will import a zipfile of images and both re-size and creeate the thumbnails.
WordPress, Popup Image Gallery Version 4.2.3 Plugin