Graduation Year

2013

Location

Atrium, Center for Natural Sciences, Illinois Wesleyan University

Start Date

14-4-2012 2:35 PM

End Date

14-4-2012 3:35 PM

Description

The phenomenon of visual perception is a fundamental process that many take for granted. Perception of color is important because it allows for the identification of food, avoidance of possible threats from the environment and communication.

Color perception begins when light from the environment is absorbed by the color detecting photoreceptors in the retina. These photoreceptors converge onto color-coded horizontal cells, ganglion cells, lateral geniculate cells of the parvocellular division and cells of the visual cortex. Understanding this relationship, Edwin H. Land coined the term “Retinex” to demonstrate that color perception involves all levels of visual processing, from retina to cortex. The goal of this project is to develop a simplified classroom demonstration of the Retinex theory of color vision. We used Kodak® black and white film to produce two images. The first image was taken using a red filter and projected with a longer wavelength of yellow light. The second image was taken using a green filter and projected using a shorter wavelength of yellow light. When each image was projected individually all that is perceived is a yellow and black image. However, when both images are projected simultaneously and superimposed, perception of color of the full visual spectrum is possible. This demonstrates that color perception is not dependant on the wavelength of light that is reflected from an object but that it occurs by comparing the ratio of longer and shorter wavelengths of light that is reflected.

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Apr 14th, 2:35 PM Apr 14th, 3:35 PM

On Edwin H. Land's Retinex Theory: Developing a Classroom Demonstration for Color Vision

Atrium, Center for Natural Sciences, Illinois Wesleyan University

The phenomenon of visual perception is a fundamental process that many take for granted. Perception of color is important because it allows for the identification of food, avoidance of possible threats from the environment and communication.

Color perception begins when light from the environment is absorbed by the color detecting photoreceptors in the retina. These photoreceptors converge onto color-coded horizontal cells, ganglion cells, lateral geniculate cells of the parvocellular division and cells of the visual cortex. Understanding this relationship, Edwin H. Land coined the term “Retinex” to demonstrate that color perception involves all levels of visual processing, from retina to cortex. The goal of this project is to develop a simplified classroom demonstration of the Retinex theory of color vision. We used Kodak® black and white film to produce two images. The first image was taken using a red filter and projected with a longer wavelength of yellow light. The second image was taken using a green filter and projected using a shorter wavelength of yellow light. When each image was projected individually all that is perceived is a yellow and black image. However, when both images are projected simultaneously and superimposed, perception of color of the full visual spectrum is possible. This demonstrates that color perception is not dependant on the wavelength of light that is reflected from an object but that it occurs by comparing the ratio of longer and shorter wavelengths of light that is reflected.