Blue period: Analyzing the color of paintings with R

While movies have been getting more orange with time, painting have been going the other direction. Paintings today are generally more blue than they were a few hundred years ago.

The image above shows the color spectrum of almost 100,000 paintings created since 1800. Martin Bellander used R to create the image, by scraping images from the BBC YourPaintings site with the help of the rvest package. He then extracted the spectrum from each of the images using the readbitmap and colorspace packages, before combining the data into the time-ordered heatmap above using the plotrix package. (You can find all of the R code in page linked at the end of this post.)

In an article for Significance magazine, Martin suggests a few possible reasons why paintings are getting bluer with time:

• The colour blue is a relatively new colour word.
• An increase in dark colours or black might drive the effect if these contain more blue or if the camera register them as blue to a larger extent.
• The colours in paintings tend to change over time, e.g. due to the aging of resins.
• Blue has historically been a very expensive colour, and the decreasing price and increased supply might explain the increased use.

He explores these hypotheses by (for example) looking at just the oil paintings over time, but the result is inconclusive. One possibility that occurs to me is the rising popularity of landscape paintings over time, which might have led to more blue skies being represented in painting. (Any art historians want to chime in?) Check out all the details of Martin's analysis at the link below.

I cannot make bricks without clay: The colors of paintings: blue is the new orange