Color is in the eye of the beholder

July 03, 2007

In some regions of Central Europe, salad dressing is made preferably with pumpkin seed oil, which has a strong characteristic nutty flavor and striking color properties. Indeed, in a bottle it appears red, but it looks green in a salad dressing or mixed with yoghurt.

Samo and Marko Kreft¡¦s paper examines the remarkable two-tone (or dichromatic) color of pumpkin seed oil, by the use of a combination of imaging and CIE (International Commission on Illumination) chromaticity coordinates. The paper also explains why human vision perceives substances like pumpkin seed oil as dichromatic or polychromatic (exhibiting a variety of colors).

Two phenomena explain the perceived shift in color of pumpkin seed oil from red to green:

Firstly, the distinctive change in color shade of the oil is due to a change in oil layer thickness. As the oil layer thickens, the oil changes its appearance from bright green to bright red. The observed color is neither dependent on the angle of observation nor on the direction or type of light.

Secondly, the shift in color is due to the unique characteristics of the cells in the human retina. Our eyes have two types of photoreceptor cells: rods and cones. Rod photoreceptor cells are very sensitive and operate in dim illumination conditions. Cone photoreceptor cells function well in bright light conditions. They are also the basis of color perception in our visual image. It is the presence of multiple classes of cone cells, each with a different spectral sensitivity, that gives us the ability to discriminate colors.
-end-
In: Kreft S & Kreft M (2007). Physicochemical and physiological basis of dichromatic colour. Naturwissenschaften (DOI 10.1007/s00114-007-0272-9)

Springer

Related Color Articles from Brightsurf:

Envision color: Activity patterns in the brain are specific to the color you see
Researchers at the National Eye Institute (NEI) have decoded brain maps of human color perception.

OPD optical sensors that reproduce any color
POSTECH Professor Dae Sung Chung's team uses chemical doping to freely control the colors of organic photodiodes.

What laser color do you like?
Researchers at the National Institute of Standards and Technology (NIST) and the University of Maryland have developed a microchip technology that can convert invisible near-infrared laser light into any one of a panoply of visible laser colors, including red, orange, yellow and green.

Increasing graduation rates of students of color with more faculty of color
A new analysis published in Public Administration found that student graduation rates improve as more faculty employed by a college or university share sex and race/ethnic identities with students.

How much color do we really see?
Color awareness has long been a puzzle for researchers in neuroscience and psychology, who debate over how much color observers really perceive.

Stretchable variable color sheet that changes color with expansion and contraction
Toyohashi University of Technology research team have succeeded in developing a variable color sheet with a film thickness of 400 nanometers that changes color when stretched and shrunk.

High color purity 3D printing
ICFO researchers report on a new method to obtain high color purity 3D objects with the use of a new class of nanoparticles.

Building a better color vision test for animals
University of Cincinnati biologists modified simple electronics to create a color vision test for fiddler crabs and other animals.

The color of your clothing can impact wildlife
Your choice of clothing could affect the behavioral habits of wildlife around you, according to a study conducted by a team of researchers, including faculty at Binghamton University, State University of New York.

Recovering color images from scattered light
Engineers at Duke University have developed a method for extracting a color image from a single exposure of light scattered through a mostly opaque material.

Read More: Color News and Color Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.