Receptive Field Neural Network Analysis Of Color Constancy And Color Contrast

Receptive Field Neural Network Analysis of Color Constancy and Color Contrast

Color constancy, or the ability of the visual system to perceive color independently of the ambient illumination, was investigated in the context of a biologically-based neural network. In particular, the role of retinal adaptation and higher level visual operations in mediating color constancy was investigated. The study incorporated properties of individual cells and how they combine to make complex color and spatial operations. The neural network simulations indicate how early visual stages complement each other to compensate and maintain relatively constant color perception under conditions of varying illumination and spatial context -in the image. The network takes advantage of several mechanisms in the human visual system, including retinal adaptation, spectral opponency, and spectrally-specific long-range inhibition. This last stage is a novel mechanism based on cells which have been described in cortical area V4. All stages include non-linear response functions. The model emulates human performance in several psychophysical paradigms designed to test color constancy and color induction. We measured the amount of constancy achieved with both natural and artificial simulated illuminants, using homogeneous gray back-grounds and more complex backgrounds, such as Mondrians. On average, the model performs well or better than the average human color constancy performance index.

Human Color Vision

Our understanding of human color vision has advanced tremendously in recent years, helped along by many new discoveries, ideas, and achievements. It is therefore timely that these new developments are brought together in a book, assembled specifically to include new research and insight from the leaders in the field. Although intentionally not exhaustive, many aspects of color vision are discussed in this Springer Series in Vision Research book including: the genetics of the photopigments; the anatomy and physiology of photoreceptors, retinal and cortical pathways; color perception; the effects of disorders; theories on neuronal processes and the evolution of human color vision. Several of the chapters describe new, state-of-the-art methods within genetics, morphology, imaging techniques, electrophysiology, psychophysics, and computational neuroscience. The book gives a comprehensive overview of the different disciplines in human color vision in a way that makes it accessible to specialists and non-specialist scientists alike. About the Series: The Springer Series in Vision Research is a comprehensive update and overview of cutting edge vision research, exploring, in depth, current breakthroughs at a conceptual level. It details the whole visual system, from molecular processes to anatomy, physiology and behavior and covers both invertebrate and vertebrate organisms from terrestrial and aquatic habitats. Each book in the Series is aimed at all individuals with interests in vision including advanced graduate students, post-doctoral researchers, established vision scientists and clinical investigators. The series editors are N. Justin Marshall, Queensland Brain Institute, The University of Queensland, Australia and Shaun P. Collin, Neuroecology Group within the School of Animal Biology and the Oceans Institute at the University of Western Australia.

Government Reports Announcements & Index