Emphasis

In Launching the imagination, Mary Stewart discusses the use of "color as emphasis."  She notes that graphic designers often use certain color combinations (like dark and bright, etc.) to emphasise important parts of a design.  One example she uses is the Annual Report for the Eaton Corporation:

She noted that "a large block of yellow combined with the word not attracts our attention to the message in the lower-left corner."  Using heavy color blocks or minimal color schemes is a very effective design technique, and has been used a lot lately.  With the new trend of flat, minimalistic designs, this kind of extreme color emphasis is more and more common.  Another example of color emphasis is the vector-style star wars posters for each episode.  

Each poster uses a specific color to draw emphasis to the storyline/setting depicted in the picture.  The minimal amounts of color also draws the eye to the white of the movie title.  Minimal color is a great way to emphasise the most importatnt part of the work, something I think all designers should explore at some point.