Imagine being able to see all the colors of the spectrum one moment, and only black and white the next. You'd think that you were missing something -- that the gray was just a stripped-down vision of reality.

But for centuries, painters have intentionally purged color from their art as a way of making it more nuanced and complex. From Jan Van Eyck, Rembrandt and Ingres, to Degas, Picasso and Gerhard Richter, artists have created -- and recreated -- images in monochrome to enhance their work.

"People think of 20th-century abstract artists as the ones who turned to black or white, but painters over the centuries who were great colorists elected to (drastically) restrict their palettes," said Lelia Packer, co-curator of the first major exhibition to explore the subject.

Featuring around 70 paintings, many of which are on loan from institutions and private collections from around the world, "Monochrome: Painting in Black and White" at London's National Gallery proves how much can be gained from the absence of color.