If you use the latest versions of WordPress you will already have noticed that when you choose the editor button to upload an image the screen goes dark and shows you in the foreground the file loading window. Well, that's jQuery and Thickbox included in the installation of WordPress.
Soinstead of installing a plugin? type lightbox with which to show larger images without leaving the page?
The process is simpler than you imagine. The first thing is to configure the options of Objects in the admin panel, in this way you can define the size of the thumbnails of the images, you put it to your liking.