This article originally appeared on Creators.
Paintings by the masters da Vinci, Rembrandt, Goya, and Caravaggio are often accepted as absolute works. Today, we use mobile devices to capture these images, compressing them onto tiny screens, and remixing them into snapchats, selfies or light simulated paintings. But technology can also reveal the secrets that lie just beneath a work's surface. Using a variety of scientific techniques and advanced digital imaging, today's scientists and art historians can non-invasively probe artworks for the secrets to artists' lives and processes.
From underpaintings that reveal new insights about an artist's true feelings, to hidden details and even in-jokes, technology is rapidly changing the way we see art. Here we've collected seven fascinating and ground-breaking discoveries that were once shrouded from both art history and the visible world.
1. The Lady with an Ermine
Leonardo da Vinci's painting, The Lady with an Ermine, was reworked twice before its final composition. According to BBC News, French engineer Pascal Cotte discovered that da Vinci changed the position of the lady's forearm and only added her symbolic ermine to the third version of his work. Using the Layer Amplification Method (LAM), a technique he and his team invented, Cotte projected intense light onto the painting and measured its reflections with a multi-lens camera. "The LAM technique gives us the capability to peel the painting like an onion, removing the surface to see what's happening inside and behind the different layers of paint," explained Cotte to the BBC. The result? Turns out, da Vinci occasionally required a do-over. Or two.
2. Old Man in Military Costume
Through macro x-ray fluorescence analysis, a painting of a portrait of a woman was discovered underneath the 380-year-old Rembrandt, Old Man in Military Costume. Previously used infrared methods weren't strong enough to reveal the underlying image. Scientists reported this was due to Rembrandt using the same pigments for the "hidden" painting as he did in his final piece.
3. The Sacrifice to Vesta
Goya's signature on The Sacrifice to Vesta was uncovered by scientists using terahertz radiation. Though the 240-year-old work did not include a true documentation of authorship, the painting marked a turning point in Goya's painting career. In May 2013, scientists at the University of Barcelona bounced terahertz waves off of the work and found a centuries-hidden signature beneath layers of paint on the bottom right hand corner.
5. The micro-positioning easel
This revolutionary new easel, developed by the Engineering and Physical Sciences Research Council, captures high resolution images of works, allowing scientists the ability to examine the techniques of the artists and date works with precision. While it isn't a discovery in and of itself, the micro-positioning easel has opened up the opportunity for hyperspectral imaging and other types of research.
6. The Blue Room
Researchers used infrared image processing to discover a painting of a bearded man in a bow-tie underneath Pablo Picasso's 1901 painting, The Blue Room. An X-ray in the 1990s first picked up a blurry image lurking beneath the murky surface. Since 2008, Patricia Favero, a conservator at The Phillips Collection has been experimenting with infrared imaging processes to analyze the painting. Earlier this year, she shared the most crisp image of its underpainting to date. Now, using fluorescence spectroscopy, the team is working on detailing the pigments to digitally recreate the piece in full color.
7. Patch of Grass
In 2008, the research team at Delft University of Technology found a mysterious portrait of a woman hiding in Van Gogh's Patch of Grass. According to NPR, the team's discovery confirmed the suspicions of many art historians—that there was something beneath the Patch of Grass. By using an X-ray process that measured the chemical makeup of the pigments, researchers were able to pinpoint the portrait lurking underneath.
Familiar with more discoveries? Working on finding some of your own? Send your discoveries here.