Multidimensional Signal Coding in the Visual System.
Abstract
Natural images contain spatiotemporal information comprised of motion and other time varying details such as flicker. Motion in the retinal image includes object motion in the visual scene, observer motion, and eye motion. Image motion presents a significant problem for efficient coding and representation of images in the visual system. The visual system must code and interpret the visual scene while accounting for objects moving at velocities which may exceed the temporal limitations of visual system processing. The visual system confronts this complex time varying signal with two spatiotemporal mechanisms: eye movements and the spatiotemporal filter arrays known as the NI and P pathways. In this paper, we examine how eye movements and the NI and P pathways conjoin to make an efficient coder of the time varying image. Eye movements limit the temporal bandwidth of images by reducing the range of velocities reaching the fovea. NI and P pathways efficiently carry image components modified by eye movements for analysis at cortical levels. The spatiotemporal properties of ganglion and lateral geniculate cells which form the M and P pathways have been extensively investigated in recent years (Kaplan & Shapley 1982: Hicks et al. 1982; Derrington & Lennie 1984; Blakemore & Vital-Durand 1986; Crook et al. 1988; Lee et al. 1989a; Purpura et al. 1990), especially the role of these pathways in coding spatiotemporal image components (Shapley & Perry 1986: Merigan 1986; Merigan 1989; Merigan & Maunsell 1990; Merigan et al. 1991; and Schiller et al. 1990). Generally the NI pathway is associated with fast temporal changes and the P pathway with high spatial acuity and colour, although there is considerable overlap across spatial and temporal frequencies. Pg12. JMD
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 17, 1995
- Accession Number
- ADA293449
Entities
People
- Gershon Buchsbaum
Organizations
- University of Pennsylvania