19 June 26
Out of Gamut
Today Ryan Moulton posted a good article about the colors your screen cannot show you and where to find them in the real world. Computer screens mix colors from red, green, and blue primaries but there are many colors the eye can discern on the color chromaticity diagram that fall outside the triangle defined by the three primaries. Mostly these are greens and cyans.
Moulton provides a guide to where to find these colors in the outdoors. Looking up at the leaves in a deciduous forest glowing in sunlight is one place. The light passing repeatedly through the leaves has the red and blue wavelengths filtered out leaving a pure spectral green at a wavelength of around 550 nm.
Another place is sunlight through depths of pure water. Water rapidly absorbs reds, and if sunlight passes through a few meters of water the color shifts outside of any screen gamut. These colors can be seen from shore when the light reflects off of light sand on the bottom, or from underwater.
Birds and butterflies famously can have intense iridescent colors thanks to the structure of their feathers and wing scales which can have elements that have the same length scale as wavelengths of visible light. Examples of these include peacock tail feathers and butterflies in the genus Morpho.
One needn’t visit nature to find colors that cannot be displayed on a screen. Green traffic lights have a color that falls mostly outside of displayable gamuts. This color has been chosen so as to provide the biggest discernment from red for viewers who are red-green colorblind. Traffic lights nowadays use LEDs which can have quite pure spectral colors.
(Thanks to MetaFilter for the link to the article.)
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