How Does Colour Vision Works
Colour vision is the ability of any organism to distinguish different light based on their wavelength of light they reflect .The visual system derives colour by comparing the responses to light from several types of cone receptor in the eyes. Colour enable use to separate object form each other and from their background as different objects tend to have different colour. On the other hand, object of the same colour are grouped together.
One of the most important functions of the human eye is to pick up and detect light. Light is a form of electromagnetic energy. Electromagnetic energy also includes cosmic rays, X rays, ultra violet rays, infrared rays, and radio. The distance from one crest of waves to the next varies greatly from the shortest, which are cosmic rays to the longest, which are radio waves. The visual system is only sensitive to a tiny portion of electromagnetic energy wavelengths of approximately 380 to 760 nanometres. Colour vision is only present in daylight (photopic vision) or under high intensity light from other sources and is absent at night (scotopic vision) or under low intensity lighting.(optic lec no) Cones function in bright conditions and rods function in dim lighting conditions. There are approximately 7 million cones and 120 million rods in the human retina; hence, the two types of receptors are not distributed evenly. The fovea, located at the back of the retina contains most of the cones and none of the rods (it allows for high acuity colour vision). The rods however, reach their maximum density slightly peripheral to the fovea and both cones and rods start to diminish towards the retinal periphery. (Physic Lab., 2002)
To understand how colour vision works we need first to understand what is colour and where does it exist? Does it exist within an object or within the light? Colour is a sensory perception, which is caused by the interaction of light with our visual perception equipment (eyes and brain). We need to understand the
One of the most important functions of the human eye is to pick up and detect light. Light is a form of electromagnetic energy. Electromagnetic energy also includes cosmic rays, X rays, ultra violet rays, infrared rays, and radio. The distance from one crest of waves to the next varies greatly from the shortest, which are cosmic rays to the longest, which are radio waves. The visual system is only sensitive to a tiny portion of electromagnetic energy wavelengths of approximately 380 to 760 nanometres. Colour vision is only present in daylight (photopic vision) or under high intensity light from other sources and is absent at night (scotopic vision) or under low intensity lighting.(optic lec no) Cones function in bright conditions and rods function in dim lighting conditions. There are approximately 7 million cones and 120 million rods in the human retina; hence, the two types of receptors are not distributed evenly. The fovea, located at the back of the retina contains most of the cones and none of the rods (it allows for high acuity colour vision). The rods however, reach their maximum density slightly peripheral to the fovea and both cones and rods start to diminish towards the retinal periphery. (Physic Lab., 2002)
To understand how colour vision works we need first to understand what is colour and where does it exist? Does it exist within an object or within the light? Colour is a sensory perception, which is caused by the interaction of light with our visual perception equipment (eyes and brain). We need to understand the
Bibliography: 1. Snowden, Thompson & Troscianko (2006) Basic Vision, Chap. 5 2. Sekuler & Blake (2002) Perception (4th ed.) Chapter 7. 4. The Physical Stimulus for Vision. (2002) [online] (http://psychlab1.hanover.edu/Classes/HumanFactors/Animations/Day4/Day4_files/v3_document.htm). [Accessed 9th of march 2007] 5. Boynton, R.M., (1971) 6. Hering, E. Outlines of a theory of the light sense. Cambridge, Mass.: Harvard University Press, 1964. (Translated from the original 1920 publication by L.M. Hurvich & D. Jameson.) 7. Nathans, J