Getty Reverse-Engineers a van Gogh

Not Van Gogh's Irises: a digital impression of how its colors might have looked originally. Factum Foundation, 2024

The colors of paintings shift over time. It is therefore possible to use our new digital toys to reconstruct the original appearance of paintings. Until recently, museums have often distanced themselves from such efforts because (a) nobody wants to advertise that beloved artworks are not exactly what the artist intended; and (b) the digital reconstructions just weren't that convincing. If the guesstimated colors are even a little off, it undermines the premise. 

The Getty Center Museum is showing one of its star paintings alongside a digital reconstruction in "Ultra-Violet: New Light on Van Gogh's Irises" (through Jan. 19, 2025). 

The original: Vincent Van Gogh, Irises, 1889. Getty Museum

The chemical industry of Van Gogh's time promoted new synthetic pigments, inexpensive and available as oil colors in handy roll-up tubes. Van Gogh, who never had much money to spend for materials, favored these mass-market paints, including the problematic red known as geranium lake. He used it from 1888 until his death in 1890, the apex of his short career. It's now known that this pigment fades rather quickly when exposed to light and oxygen. This can affect not only reds but anything made from red, such as purples made by mixing red and blue. 

Getty conservators used X-ray fluorescence scanning to map the use of geranium lake in Irises. This allowed an algorithm to output a plausible original color map. The Madrid-based Factum Foundation for Digital Technology in Preservation then converted the latter to a inkjet print on a textured surface mimicking Van Gogh's impasto. 

The first thing to say is that, despite the build-up, the colors in Van Gogh's painting and its digital simulacrum are not all that different. I'm reproducing images taken with the same phone camera under gallery lighting. Yes, today's blue irises were once a bluish purple (says the algorithm), and the reddish soil is a few shades more vibrant in the reconstruction. Looking at the images side-by-side, I prefer the color balance of the simulation to the real thing. It seems like Van Gogh's color sense turned up to 11. 

But my main takeaway is that the Getty painting's colors are in relatively good shape. Were you to imagine swapping Irises for its digital fake, in its usual gallery, I'd guess that few Getty visitors would notice . 

Vincent Van Gogh, Irises, 1890. Metropolitan Museum

Other Van Gogh paintings have more serious issues with fading red pigment. The Metropolitan Museum has an indoor still life of irises in a vase, done about 7 months after the Getty painting. In a letter the artist described the wall behind the New York bouquet as pink. That would have been a mix of white and red. You can detect a ghost of pink in the wall by comparing it to the white vase. The fresh painting surely had a different emotional register than it does now.

One of the more dramatic color-shifts is at the Norton Simon Museum. Van Gogh's painting of his mother was based on a photograph sent by his sister Wilhelmina (a feminist nurse who spent her last 38 years in a psychiatric asylum). "I am working on a portrait of Mother for myself, because the black-and-white photograph annoys me so," Vincent wrote. The resulting painting is almost a Wicked Witch green. Mom Van Gogh owned both the Simon picture and the Met Irises. 

The present appearance of the Simon portrait has led some to conclude that Van Gogh intended a cadaverous (or proto-Fauvist) effect. The green palette is now understood to be a consequence of defective chemicals, transforming a ruddy-complected portrait with cool shadows into a Frankensteinian wraith. 

"Paintings fade like flowers," Van Gogh complained in an April 1889 letter to brother Theo, the month before he painted Irises. 

Chemistry, Walter White said, is the study of change.

Vincent Van Gogh, Portrait of the Artist's Mother, 1888. Norton Simon Museum