Investigation of a Linear Systems Model for Human Visual Detection and Spatial Frequency Discrimination
Abstract
This research investigated the application of a linear systems model to two parameters of vision: the contrast threshold and the spatial frequency difference threshold. The contrast threshold is the contrast of a target when an observer is just able to detect its presence. The spatial frequency difference threshold is the smallest difference in spatial frequency that permits two grating targets to be distinguished. The model investigated was for observation with a fixed visual field size of one-dimensional, time-invariant sinusoidal grating targets. A mathematical development indicated that a linear model could be used to represent the human spatial frequency difference threshold function. The model was implemented using an electro-optical hardware system which consisted of a charge-coupled device video camera, a frame grabber, and a personal computer. Because of its similarities to the structure of the eye, linear response, and ability to acquire digital image data, a charge coupled device array video camera and frame grabber were used to simulate the eye. The action of the neural pathways and visual cortex was simulated by Fourier transform computations on the camera and frame grabber output. The experimental data from the electro-optical hardware system agreed with the theoretical models for both parameters.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1988
- Accession Number
- ADA209397
Entities
People
- Harold S. Merkel
Organizations
- Armstrong Laboratory