A new camera system and associated software package allows scientists to produce videos that accurately replicate the colors that different animals see in natural settings.
Different animals perceive the world differently because of the capabilities of the photoreceptors in their eyes.
For example, animals like honeybees and some birds can see UV light, which are outside the range of human perception.
Reconstructing the colors that animals actually see can help scientists better understand how they communicate and navigate the world around them.
False color images give us a glimpse into this dynamic world, but traditional methods such as spectrophotometry are often time consuming, require specific lighting conditions, and cannot capture moving images.
“How do animals see the world?” said senior author Dr. Daniel Hanley from George Mason University and colleagues.
“This simple question has captured our imaginations and spurred discovery since the advent of modern science.”
“Each animal possesses a unique set of photoreceptors, with sensitivities ranging from ultraviolet through infrared, adapted to their ecological needs.”
“In addition, many animals can detect polarized light,” they said.
“As a result, each animal perceives color differently. As neither our eyes nor commercial cameras capture such variation in light, wide swaths of visual domains remain unexplored.”
“This makes false color imagery of animal vision powerful and compelling.”
Vasas et al. show 3 male orange sulphurs (Colias eurytheme). These butterflies display strong angle-dependent UV iridescence on the dorsal side of their wings. The UV-iridescent portions appear more orange to the human observer than the otherwise yellow wings (see human-visible inset). The avian false color depiction (main image) is based on the coordinates of the receptor noise-limited (RNL) opponent space. Coordinates in this space represent differences in an animal’s photoreceptor responses, and the distances between the coordinates approximate the perceptual distances between the colors. The inset color key illustrates human-visible colors around the perimeter of a circle colored according to RNL coordinates, where UV colors start at the epicenter and mix with other colors. In this depiction, the UV-iridescent portions appear purple, because they most strongly reflect in the ultraviolet and the red part of the spectrum. The ventral part of the wings, visible when the animals are in their resting position, are depicted as gray-brown, just like the leaves, as they are close to the achromatic point. Image credit: Vasas et al., doi: 10.1371/journal.pbio.3002444.
To address these limitations, the researchers developed a novel camera and software system that captures animal-view videos of moving objects under natural lighting conditions.
The camera simultaneously records video in four color channels: blue, green, red and UV.
These data can be processed into ‘perceptual units’ to produce an accurate video of how those colors are perceived by animals, based on existing knowledge of the photoreceptors in their eyes
The scientists tested the system against a traditional method that uses spectrophotometry and found that the new system predicted perceived colors with an accuracy of over 92%.
This novel camera system will open new avenues of research for scientists, and allow filmmakers to produce dynamic, accurate depictions of how animals see the world around them.
The system is built from commercially available cameras, housed in a modular, 3D-printed casing, and the software is available open-source, allowing other researchers to use and build on the technology in the future.
“We’ve long been fascinated by how animals see the world,” Dr. Hanley said.
“Modern techniques in sensory ecology allow us to infer how static scenes might appear to an animal; however, animals often make crucial decisions on moving targets (e.g., detecting food items, evaluating a potential mate’s display, etc.).”
“We introduce hardware and software tools for ecologists and filmmakers that can capture and display animal-perceived colors in motion.”
The team’s work was published in the journal PLoS Biology.
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V. Vasas et al. 2024. Recording animal-view videos of the natural world using a novel camera system and software package. PLoS Biol 22 (1): e3002444; doi: 10.1371/journal.pbio.3002444