Lausanne museum unveils the secrets of the first color photographs

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An exhibition on Gabriel Lippmann, the inventor of one of the first methods for color photography, opens today at the Photo Elysée museum in Lausanne and will run until 21 May. The exhibition provides a unique glimpse into Lippmann’s multispectral imaging technique - for which he was awarded the Nobel Prize - by presenting his original color plates in an entirely novel way, thanks to a joint project with EPFL.

Gabriel Lippmann: Color Photography, opening today in Lausanne, is the culmination of years of collaborative work. It highlights images from the museum’s Gabriel Lippmann collection: 137 of the approximately 250 plates currently in existence worldwide. In designing the exhibition, Photo Elysée worked closely with researchers at LCAV, within EPFL’s School of Computer & Communication Sciences, to come up with an effective method for displaying the plates and the color reproduction technique that earned Lippmann the 1908 Nobel Prize in physics.

The collaboration - which took place in three phases over several years - involved exploring the mechanisms of multispectral imaging. "First, the researchers helped us better understand Lippmann’s imaging process," says Pauline Martin, the exhibition curator. "Then they gave us ideas for explaining the process in a way that’d be easy for the general public to understand. And finally, they worked with us to create display cases with an elaborate lighting system that lets visitors view the original images." Around 20 Lippmann plates are on display, in sizes ranging from 5 cm on a side to around 10 to 13 centimeters on a side. "We’re delighted to be able to share these impressive, captivating images with the public," says Martin.

Arnaud Latty, a member of the LCAV research group that’s studying Lippmann plates (see box), contributed his expertise to the project, for instance by helping to design the display cases. "Each plate has to be viewed from a specific angle in order to see its image in full without noise or distortion," he says. "We therefore created slanted stands for the plates to lie on, along with an innovative lighting system comprising a lamp, diffuser and lens." To give visitors an idea of how the image would appear without this kind of special display case, similar plates are set up in parallel, which visitors can move around and try to find the right viewing angle themselves.

The museum also worked with LCAV to build demonstrators for the exhibition, giving visitors an opportunity to delve into the science behind the plates. The demonstrators include a machine that breaks white light down into a rainbow of colors and compares them with reproductions obtained using different photographic methods. Another machine lets visitors run a mechanics experiment with a vibrating cord, where each sound the cord makes corresponds to a given color. Here too, visitors get insight into the nature of Lippmann’s technique.

Gabriel Lippmann: Color Photography will be on display from 3 March to 21 May at Photo Elysée, Cantonal Museum for Photography, Place de la Gare 17, Lausanne. // .

The science behind Lippmann plates

The LCAV researchers published their findings in Proceedings of the National Academy of Sciences (PNAS) in early 2021; a second article , appearing last year in IEEE Transactions on Signal Processing, takes a look at the underlying mathematical model. In these articles, the authors explain that most photographic methods take just three measurements - for red, green and blue. However, they discovered that Lippmann’s historical approach typically captured 26 to 64 spectral samples of information in the visible region. His technique, based on the same interference principles that recently enabled gravitational waves to be detected - and which is the foundation of holography and much of modern interferometric imaging - has been almost completely forgotten today.
The researchers wondered whether it would be possible to accurately recreate the original light of these historical scenes, but they also wanted to create digital copies of them and, ultimately, figure out how the technique worked. They ended up modeling each step of the process - from the multi-spectral image being reflected back from a Lippmann plate to its recording in a photograph. In addition, they were able to capture the reflected light and measure how it differed from the original. Learn more.