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The Meaning(s) of Shape
Published in F. Brent Neal, John C. Russ, Measuring Shape, 2017
Human vision is a complex process and a rich subject for study. The visual system involves processing in the eyes, the visual cortex, and other parts of the brain. The literature, which includes physiology, psychology, and many other fields, is vast. The subject is introduced here because some computer image-processing tasks attempt to emulate either the low- or high-level processes that are believed to take place. More comprehensive reviews of the processes involved in vision can be found in books such as Frisby (1980), Marr (1982), Rock (1984), Hubel (1988), Posner and Raichle (1994), Parks (2001), Ings (2008), Gregory (2009), and Frisby and Stone (2010). Culture adds another dimension to a complicated topic: westerners and Asians do not “see” the same things or at least do not extract the same information from images of scenes (Nisbett, 2004; Nisbett & Masuda, 2003).
Visual psychophysics and color appearance
Published in Sharma Gaurav, Digital Color Imaging Handbook, 2017
Garrett M. Johnson, Mark D. Fairchild
To gain an understanding of color, one of the foremost requirements is to have a basic understanding of the human visual system. Traditionally, the study of the human visual system generally falls into two categories: physiology and psychophysics. The study of the physiology of the human visual system involves examining the functionality of the receptors and neurons of the eye and the brain. This study is beyond the scope of this chapter, though there are several excellent texts on the subject.7–9 Visual psychophysics is a technique for examining the relationship between physical measurements of a stimulus with the perception of that stimulus. More details of the experimental methods described in this chapter can be found in various texts, notably by Fairchild,1 Bartleson and Grum,11 Gescheider,12 Torgeson,13 Thurstone,14 and Engeldrum.15
Luminous Environment Design Strategies
Published in Chitrarekha Kabre, Synergistic Design of Sustainable Built Environments, 2020
The visual system involves the eye and the brain working together to process the image and interpret the visual environment. The optical elements of the eye form an image of the world on the retina. At the retina, photons of light are absorbed by the photoreceptors and converted to electrical signals. These signals are transmitted by the optic nerve to the lateral geniculate nucleus (LGN) and then to the visual cortex for visual processing. In addition to the neural pathways from the eye to the visual cortex, there are many other pathways leaving the optic nerve shortly after it exits the eye that control pupil size, eye movements, and circadian rhythms.
A new model for face detection in cluttered backgrounds using saliency map and C2 texture features
Published in International Journal of Computers and Applications, 2018
Somayeh Saraf Esmaili, Keivan Maghooli, Ali Motie Nasrabadi
The human visual system can simply detect and recognize faces in varied situations with high accuracy and speed. Based on need, scientists have done different computer vision experiments to understand how visual system works and recognizes objects over the decades [3,4]. The visual system is organized in two functionally specialized processing pathways in the visual cortex. One pathway (from the primary visual cortex to the parietal cortex for controlling eye movements and visual attention) is named dorsal stream and other pathway (from the primary visual cortex towards the inferior temporal lobe, including V1, V2, V4, posterior infer temporal (PIT), and anterior infer temporal (AIT) is named ventral stream, which processes detail of objects and faces in different [5,6]. Both the dorsal and the ventral streams are not completely independent and in higher areas, there are interactions. As, some areas in AIT send top-down information such as target object’s color and texture features to the low-level visual attention areas such as LGN (lateral geniculate nucleus) to find salient object regions [7–10].
Emerging photoelectric devices for neuromorphic vision applications: principles, developments, and outlooks
Published in Science and Technology of Advanced Materials, 2023
Yi Zhang, Zhuohui Huang, Jie Jiang
Adaptation of the human eye is the process by which the visual system adjusts its threshold for the perception of light according to the brightness of external stimuli [17,142]. This function allows the human eye to avoid the damaging effects of light in a changing environment. Jin et al. [135] observed negative photoconductivity for the first time in the photoelectric ion-gel-gated In2O3 transistor. They designed a transistor array for the artificial visual perception system that can be adaptive to environmental light. As shown in Figure 8(g), the electrical stimulation signals were applied to the array in the dark and light conditions, respectively. The difference in currents before and after stimulation is defined as ΔIn. Figure 8(h) shows the ΔIn values triggered by the electrical signals for different stimulus times in the dark and light conditions, respectively. The upper one of Figure 8(h) is used to demonstrate the visual dark adaptation process. As the stimulus number increases, the ΔIn values of the pixels gradually fall all the way to the red threshold region. This indicates that the device completes the self-adaptation process in the dark. The visual light adaptation process of the device is shown in the lower one of Figure 8(h). The ΔIn values are at a higher level in the blue threshold region. The experimental results show that the transistor array can adjust the threshold range to achieve adaptive behavior to dark and light, similar to the human eye. This study provides a new way to build an artificial visual perception system with environmental adaption.
VNG technique for a convenient vestibular neuritis rating
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2020
Hanene Sahli, Amine Ben Slama, Sami Bouzaiane, Jihene Marrakchi, Seif Boukriba, Mounir Sayadi
Vestibular disease caused by balance disorders still persists in spite of the existence of many motivated investigations (Halmagyi et al. 2010; Kim et al. 2012). The vestibular disorder (VD) can produce disequilibrium or vertigo produced by an unilateral reflectivity of the vestibule. The vertigo is nearly a reason of clinical observations in order to obtain a satisfactory analysis via the Videonystagmograph test. This leads to appreciate the vestibular input mechanisms caused by the visual system, central nervous system extraocular muscles and vestibular nerve. These systems integrate pathologies of inner ear structures like the eighth cranial nerve that decreases the information related to the eye movements and head position (Fishman et al. 2011).