KAIST

A research team, consisting of Professor Hawoong Jeong of the Department of Physics at KAIST and Assistant Professor Seung-Woo Son of the Department of Applied Physics at Hanyang University, conducted a research project to understand visual representations through the eyes of science, i.e., quantitative analyses. Researchers took a sample of reproductions of European paintings from the 11^th to the early 19^th centuries and analyzed them based on three elements: the usage of color, the variety of painted colors, and the brightness of the images.

For the large-scale quantitative analysis, the research team utilized digital images of the paintings obtained from the Web Gallery of Art, a virtual museum and searchable database of European fine arts that includes over 29,000 pieces, ranging from the years 1000 to 1850. The Web Gallery classifies paintings into ten art historical periods such as Medieval, Renaissance, Mannerist, Baroque, Rococo, Romantic, and Realist.

For each period, researchers investigated the frequency of certain colors which appear in paintings and examined the variety of painted colors, paying particular attention to paintings created by two iconoclastic artists from different eras: Pieter Bruegel the Elder and Jackson Pollock. In their works, the researchers discovered that specific pigments were preferred in each period, the result of reflecting historical facts into fine arts. For example, certain rare colors were used in the medieval age for political and religious reasons, and artists in that era employed a technique to layer one color over another dry color in order to express mixed colors, resulting in thickly textured brushstrokes because they considered mixing colors impure. Moreover, oil colors and color mixing techniques were not fully developed until the Renaissance age. 

According to the research team, fewer numbers of colors were used before the 20^th century, and the introduction of new expressionist tools, like the use of pastels and fingers directly on canvas, and painting techniques, such as “chiaroscuro” and “sfumato,” made much more colorful and natural expressions possible after the Renaissance period. The team said that the color arrangement of Jackson Pollock’s drip paintings differed substantially from other paintings, showing randomness, especially in the spatial arrangement of colors.

Researchers also examined one of the artistic effects applied to paintings, contrast, an important element to express shape and space in two dimensional fine arts. Among various types of contrasts, they said, brightness contrast is the most important in art history due to the cultural background of Europe which usually adopts the contrast of light and darkness as a metaphorical expression. Taking the color information of pixels and their spatial arrangement, the researchers studied the prevalence of brightness contrast in European paintings over ten artistic periods by developing a correlation function to measure the contrast. These mathematical measurements quantitatively describe the birth of new painting techniques including chiaroscuro and sfumato and their increasing use. For instance, in the medieval age, the contour of objects or images in paintings was vague, but it became much clearer later in the Romantic period.    

Professor Jeong said, “The complexity of the material world has been a long-lasting topic of interest in natural science, but research in the structural complexity of art and humanities has only begun since the development of the Internet, with the availability of big data in these fields. Our research is a meaningful attempt to understand the underling intricacy of art and humanities based on a scientific approach, expressed quantitatively.”

The research results were published online on December 11, 2014 in Scientific Reports, entitled “Large-Scale Quantitative Analysis of Painting Arts.” The paper was also selected as one of the weekly research highlights by Nature and is noted on its online journal’s website.   

YouTube link on “the brightness contrast”: http://youtu.be/SFo0h1EU2aw

Figure 1: Constructing brightness surfaces and measuring roughness exponents

Figure 2: Visual representations of Mona Lisa painted by Leonardo da Vinci, which was reproduced in accordance with the art historical periods

Figure 3: The screenshot of Nature online webpage