Lightness Brightness And Transparency
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Lightness, Brightness and Transparency
Author: Alan L. Gilchrist
language: en
Publisher: Psychology Press
Release Date: 2013-09-05
This volume deals with the visual perception of lightness, brightness, and transparency of surfaces, both under minimal laboratory conditions and in complex images typical of everyday life. Each chapter analyzes the challenging problem of how a pattern of light intensities on the retina is transformed into the visual experience of varying shades of grey, transparent surfaces, and light and shadow. One important theme which unifies the group of contributions is the recognition that the perception of surface lightness is rooted fundamentally in the encoding of relative intensities of light within the retinal image, not intensities per se. A second important unifying theme is an appreciation of the multiple dimensions of the visual experience of lightness, brightness, and transparency -- people do not perceive the lightness of surfaces by discarding information concerning the light illuminating those surfaces; rather, they perceive a pattern of illumination projected onto a pattern of surface greys. The long-fascinating problems of surface lightness and color perception have become very active topics recently as a resurging interest within the visual perception community has coincided with an increasing appreciation of the centrality of these problems by the emerging machine vision community. The best of recent psychophysical work on lightness perception, as presented in this volume, will be of great interest to both of these communities. This book also marks a synthesis of old and new. A traditional, strongly Gestalt, approach that had fallen into neglect is updated in the light of new quantitative systematic methods and important later discoveries, such as the disappearance of stabilized retinal images. The book draws on such diverse approaches as Gestalt and ecological psychology, threshold psychophysics, and computational vision, advancing our understanding of the interrelations among surface color, illumination, perceived depth, shading, and transparency.
Lightness, Brightness, and Transparency
First Published in 1994. Routledge is an imprint of Taylor & Francis, an informa company.
Lightness, Brightness, and Transparency in Optical See-through Augmented Reality
"Augmented reality (AR), as a key component of the future metaverse, has leaped from the research labs to the consumer and enterprise markets. AR optical see-through (OST) devices utilize transparent optical combiners to provide visibility of the real environment as well as superimpose virtual content on top of it. OST displays distinct from existing media because of their optical additivity, meaning the light reaching the eyes is composed of both virtual content and real background. The composition results in the intended virtual colors being distorted and perceived transparent. When the luminance of the virtual content decreases, the perceived lightness and brightness decrease, and the perceived transparency increases. Lightness, brightness, and transparency are modulated by one physical dimension (luminance), and all interact with the background and each other. In this research, we aim to identify and quantify the three perceptual dimensions, as well as build mathematical models to predict them. In the first part of the study, we focused on the perceived brightness and lightness with two experiments: a brightness partition scaling experiment to build brightness scales, and a diffuse white adjustment experiment to determine the absolute luminance level required for diffuse white appearances on 2D and 3D AR stimuli. The second part of the research targeted at the perceived transparency in the AR environment with three experiments. The transparency was modulated by the background Michelson contrast reduction in either average luminance or peak-to-peak luminance difference to investigate, and later illustrated, the fundamental mechanism evoking transparency perception. The first experiment measured the transparency detection thresholds and confirmed that contrast sensitivity functions with contrast adaptation could model the thresholds. Subsequently, the transparency perception was investigated through direct anchored scaling experiment by building perceived transparency scales from the virtual content contrast ratio to the background. A contrast-ratio-based model was proposed predicting the perceived transparency scales. Finally, the transparency equivalency experiment between the two types of contrast modulation confirmed the mechanism difference and validated the proposed model."--Abstract.