Color is in the eye of the beholder

Jul 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.

Citation: Kreft S & Kreft M (2007). Physicochemical and physiological basis of dichromatic colour. Naturwissenschaften (DOI 10.1007/s00114-007-0272-9)

Source: Springer

Explore further: Freedom and responsibility of science

add to favorites email to friend print save as pdf

Related Stories

Hitchhiking robot reaches journey's end in Canada

3 hours ago

A chatty robot with an LED-lit smiley face sent hitchhiking across Canada this summer as part of a social experiment reached its final destination Thursday after several thousand kilometers on the road.

Microsoft to unveil new Windows software

4 hours ago

A news report out Thursday indicated that Microsoft is poised to give the world a glimpse at a new-generation computer operating system that will succeed Windows 8.

Recommended for you

Freedom and responsibility of science

5 hours ago

Yesterday, the German Research Foundation (DFG) and the Leopoldina National Academy of Sciences presented their recommendations for "The Freedom and Responsibility of Science" in Berlin. Both research organizations appeal ...

What I learned from debating science with trolls

Aug 20, 2014

I often like to discuss science online and I'm also rather partial to topics that promote lively discussion, such as climate change, crime statistics and (perhaps surprisingly) the big bang. This inevitably ...

Activists urge EU to scrap science advisor job

Aug 19, 2014

Nine major charities urged the European Commission on Tuesday to scrap a science advisor position it says puts too much power over sensitive policy into the hands of one person.

More to a skilled ear in music

Aug 15, 2014

The first pilot study in Australia to give musicians the skills and training to critically assess music by what they hear rather than what they see begins this month at the Sydney Conservatorium of Music.The study aims to ...

User comments : 0