LECT02-4 (1).pdf - Elements of visual perception Computer...

This preview shows 1 out of 3 pages.

Dr. D. J. Jackson Lecture 2-1 Electrical & Computer Engineering Computer Vision & Digital Image Processing Dr. David Jeff Jackson Electrical & Computer Engineering The University of Alabama Dr. D. J. Jackson Lecture 2-2 Electrical & Computer Engineering Elements of visual perception Goal: help an observer interpret the content of an image Developing a basic understanding of the visual process is important Brief coverage of human visual perception follows Emphasis on concepts that relate to subsequent material Dr. D. J. Jackson Lecture 2-3 Electrical & Computer Engineering Cross section of the human eye Eye characteristics nearly spherical approximately 20 mm in diameter three membranes cornea (transparent) & sclera (opaque) outer cover choroid contains a network of blood vessels, heavily pigmented to reduce amount of extraneous light entering the eye. Also contains the iris diaphragm (2-8 mm to allow variable amount of light into the eye) retina is the inner most membrane, objects are imaged on the surface Dr. D. J. Jackson Lecture 2-4 Electrical & Computer Engineering Retinal surface Retinal surface is covered in discrete light receptors Two classes Cones 6-7 million located primarily near the center of the retina (the fovea ) highly sensitive to color can resolve fine details because each is attached to a single nerve ending Cone vision is called photopic or bright-light vision Rods 75-150 million distributed over the retinal surface multiple rods connected to a single nerve ending give a general overall picture of the field of illumination not color sensitive but are sensitive to low levels of illumination Rod vision is called scotopic or dim-light vision
Image of page 1

Subscribe to view the full document.