Though a seemingly universal element of art, the way artists deploy color has changed dramatically over time. In the middle ages and the renaissance, pigment costs made color a luxury, and certain colors (like blue, made of rare lapus lazuli) were reserved for royalty. In the 20th century, the advent of commercially-available tubes of paint and cheap pre-mixed acrylics opened new possibilities for artists. Alongside the theoretical re-evaluation of what a work of art should be, this historical development was crucial to the post-war avant-garde, who began to explore color as the subject of art itself.

Exemplary of this approach are the theoretical color exercises practiced by the Bauhaus school founder Josef Albers. His iconic Homage to the Square series uses the simple premise of opaque concentric squares to demonstrate that our perception of color only exists within a relative context. Set against a color opposite it on the color wheel, a hue will appear more vibrant and foregrounded, while a warm or cool hue set next to another color of similar temperature will appear duller.

Helen Frankenthaler's Lilac Sweep, a lithograph in seven colors, shows the abstract expressionist artist also exploring color contrasts within a composition. Though the bottom-heavy gradient wash of lilac evokes a calming seascape, five thin lines in hyper-concentrated primary pigments thwart that illusionistic view, instead centering the artist's hand on a flat surface, and bringing the focus back to the serene color combinations.

Perhaps in reaction to the hyper-individuated textures of the abstract expressionists, color took on a different role in the "hard-edged abstraction" tendency within the minimalist movement of the late '60s and '70s (Albers’ Square series is considered within this framework too). Minimalism was marked by paint application with rulers or tape to achieve the depersonalized exactitude of commercial artists (though without the aim of compelling a buyer). In Donald Judd's Untitled (#194), a thin red line seems to "hold back" an orange rectangle that pulses underneath it, centering our focus on color and composition alone.

A later generation of abstract artists freed color from the compositional purism of their forbearers. In the red and citrus-toned Tanagra by James Siena, vibrant color estranges its source imagery, a topographical map (possibly of the Greek city for which it is named), while in Light Catcher James Rosenquist uses his signature maximalist approach to color to make a celebratory composition of fuchsia against spots of green that evokes the tangled blooms of tropical plants.

The limited dichromatic palette of Mary Heilmann's Lineup 2 is more restrained, but its play of color is just as evocative. Deft cloud-like strokes of marine blue pigments "float" in an opaque form over a lighter tint. The subtle contrast provides the illusion of depth to an otherwise abstract painting, an exercise in color theory that would have been welcome in Josef Albers' classes.