contrast assignment

Contrast-the difference in luminance or color that makes an object (or its representation in an image or display) distinguishable.
      
      ~size contrast- difference in the 
       

http://girottifamily.typepad.com/.a/6a00d83451c80d69e20120a527272f970c-500wi

       ~shape contrast- difference in the texure and/or color

http://www.neilblevins.com/cg_education/composition_contrasts/figure21.jpg

      ~texture/color contrast- difference in the shapes

http://s.hswstatic.com/gif/photo-contrast2.jpg

Emphasis-special importance, value, or prominence given to something.

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQQDbHVK2dpapnBEGYvYsAh26zY9SlxkVygwhXTwZUl3Q-Ar_3lDQ

Balance- an even distribution of weight enabling someone or something to remain upright and steady.

             

            ~informal balance- 

        objects have nearly the same "visual weight" on either side of the vertical center of the photograph composition, but are different in size, shape, texture, or value.

http://jaireaton.com/Digtial_Photography_svhs/Photography/Pages/Formal_%26_Informal_Balance_files/shapeimage_1.png

              ~formal balance- Each side of the vertical center of a photograph has equal weight and have similar or exactly the same shape, texture, and value 

https://nikkismith04.files.wordpress.com/2012/05/formal-balance-edited.jpg