Martin Bellander scraped the color data from 120,013 paintings — most of them produced between 1800 and 2000 — then wrote statistical software to extract color data from them.

Bellander:

There seems to be a reliable trend of increasingly blue paintings throughout the 20th century! Actually almost all colors seem to increase at the expense of orange. But let’s focus on the increase of blue.

and:

Of course the changes in color might be a results of a combination of factors. One of these could of course be trends in the use of color. If we assume a smooth linear deterioration of certain colors in oil paintings, it would be possible to subtract that change and study the short term fluctuation in color use. For example the marked increase of blue at the time of the First World War, might actually reflect a true trend in color use.

Regardless of the reason(s) why blue has become more prominent, it’s fascinating to see this trend emerge from the analysis itself.