References:

Rhythm: Screenshot from Portal - Video Game

Proportion: http://wallpapernet.eu/wp-content/gallery/2_galaxy_wallpaper_03/galaxy-wallpaper.jpg

Figure-Ground: http://www.johnsonpestcontrol.com/wp-content/uploads/2011/02/honey-bee-gs.jpg
http://www.australiangeographic.com.au/assets/images/article/journal/04_Bee_crEgoGuitto_gal.jpg

Datum: http://www.call-wild.com/photos/Dogsled3.jpg
http://changedesktop.com/wp-content/uploads/2011/01/snow_by_all_my_life_i_dream.jpg

Contrast: http://www.imgbase.info/images/safe-wallpapers/digital_art/3d_space_scene/6500_3d_space_scene_hd_wallpapers.jpg

Symmetry: http://images.buystarwarscostumes.com/authentic-stormtrooper-cost.jpg