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A Vibrant Violet Revelation: Van Gogh’s Irises through the lens of Color Science

Recent scientific examination of Van Gogh’s Irises revealed that the painting’s iris flowers, which today appear blue, were once purple. A key finding of the study was the identification and mapping of the light-sensitive red pigment geranium lake, which was mixed with three blue pigments—cobalt blue, ultramarine, and Prussian blue—to create the various shades found in the irises. When initially applied, the mixture of red geranium lake with the blue pigments would have created shades of purple. But, how purple?

A team of conservators, scientists, and imaging specialists collaborated to create a 1:1, 3D physical reconstruction of how the painting may have originally appeared. Optical microscopy of a cross-section sample revealed a glimpse of the unfaded purple paint mixture shielded beneath the surface. However, reimagining the full range of purples could not be simply extracted from this single visual point of reference.

To address this, we turned to color science. By modeling the optical properties of the unfaded pigment mixtures (as determined from chemical analysis), we created a series of tone palettes with known relative pigment concentrations—similar to paint swatches from a hardware store. These palettes bracketed the gamut of purples Van Gogh could have reasonably mixed up. Starting with the relative amounts of geranium lake and blue pigments observed in each paint stroke, we selected ranges of purple tones from the palettes and recolored the brush strokes accordingly. The result: vibrant purple irises with intricately gradated tones, rendered through scientific modeling and applied with artistic sensibility.

This lecture will discuss how the interdisciplinary team linked the scientific and aesthetic understanding of the faded flowers, enabling effective communication and consensus on “how purple” the irises originally were.

Speaker bio:

Olivia is the Lead Technical Imaging Specialist in the Getty’s Digital Imaging Department (GDID), where she guides Getty-wide advanced imaging initiatives to improve the capture, management, and dissemination of scientific imaging data. Her focus on optimizing technical imaging workflows across GDID’s photography studios is enhancing how Getty supports imaging for Open Science, Open Content, and computational cultural heritage efforts, and emphasizes the new avenues that spectral imaging techniques and technologies provide toward these efforts.

Prior to this role, Olivia was an Assistant Scientist at the Getty Conservation Institute, where she conducted technical studies on works of art to address questions of composition, artistic practice, and material degradation. Her projects there also focused on imaging, in particular, on expanding the Institute's capabilities in hyperspectral imaging and incorporating it with other scientific imaging modalities, such as macro X-Ray fluorescence scanning.

Olivia earned a PhD in color science from Rochester Institute of Technology, as well as MS and BS degrees in chemistry from RIT and Penn State, respectively.