ewteam/EWSEL-Lightbox-For-Galleries — pull request #1 by smehrbrodt (2013-12-23 10:24:50+00:00)
Title: Use the user-defined "large" size for images

"large" is the size the user sets in the Wordpress options.
So this might be the preferred size of a user for the full screen image.

See: http://codex.wordpress.org/Function_Reference/wp_get_attachment_image_src