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Perception of Images. Modern Trends

Iftikhar B. Abbasov

Southern Federal University, Academy of Engineering and Technology, Department of Engineering Graphics and Computer Design, Taganrog, Russia

Abstract

This chapter outlines the survey of some current lines of research in the field of visual information perception. The peculiarities of the eye anatomy of vertebrates, the structural elements of the visual system, the process of the senses and the perceptual organization of visual information by the brain are analyzed. The modes of eye movements, the structure of the eye bulb, current methods and means of eye movement recording are described. The questions concerning the perception of contour, light contrast and types of color sensing disorders are represented. The concepts of figure and ground are defined, and the factors of gestalt grouping, subjective contours and images recognition in space are analyzed. The peculiarities of monocular and binocular vision are pointed out. The process of perceptual organization, constancy factors, types of visual illusions and causes of their occurrence are described.

Keywords: Visual system, sense, perception, types of eye movements, color sensing disorder, factors of gestalt grouping, monocular and binocular vision, visual illusions

1.1 Visual System

1.1.1 Some Modern Research

Let's specify some works with a focus on the questions relating to visual perception. The work of [Pepperell, 2019] deals with the conceptual problems of visual perception with respect to the field of art. The author is a painter, and some of his pictures in the context of which the phenomenon of perception of works of pictorial art (Figure 1.1.1) is envisaged are represented in the work. In the opinion of the author the science is based on rational descriptions, and the art uses artful, aesthetic and philosophical concepts. The statement of German von Helmholtz about the perception of the external environment is mentioned. The qualities of our senses are projected on the objects in the external environment. They seem to be colorful, red or green, cold or warm, with smell or taste. Even understanding that these concepts are subjective and belong to the properties of our nervous system, the art can help us understand the complicated perception problems.

In the opinion of the author the perception of the real world and perception of images of the real world represent the extremely knotty problem associated with the rationality notion. The study of these problems may help us achieve progress in understanding perception in the context of art and current scientific and intellectual breakthroughs.

The results of a study of neuroelectrical brain activity in the course of perception of a particular set of images are presented in the work of [Maglione et al., 2017]. The original (Original set) and stylized pictures by Titian and a contemporary painter were shown to the selected group of people who passed the art studies. The stylized pictures were got from the original ones by means of leaving the color patches (Color set) and contour forms (Style set) (Figure 1.1.2). The picture and its processed images of L.D. Kampan, the modern painter, are represented in the first row, and the picture by Tiziano Vecellio and the relevant processed analogs in the second row. The research subjects were randomly affected by the offered irritators.

In the course of experimentation it has been found that the Original set induced more emotions than other sets of pictures during the first 10 seconds. The emotions brought out by Color and Style sets were intensified in 30 seconds. However, the emotions held steady for the first Original set. The evidences of cortical activity stream from the parietal and central regions to prefrontal and frontal regions in the course of viewing of images of all data sets were detected throughout the whole experiment. This result is congruent with the idea that active perception of images with the sustained cognitive attention in the parietal and central regions leads to the forming of judgments about their aesthetic valuation in the frontal region of head.

Figure 1.1.1 "Grey on orange", "Flower", "Drawing drawing" [Pepperell, 2019].

Figure 1.1.2 Example of three groups of stimuli tested in study (Original, column (a); Style, column (b); Color, column (c) [Maglione et al., 2017]).

It has been found that different regions of the brain including not only the frontal but also the motional and parietal cortical layers take part in the valuation of perceivable stimuli. It is necessary to admit that the prefrontal dorsolateral brain cortex is selectively activated by the only stimuli considered to be attractive. At the same time, the prefrontal activity is generally activated during the valuation of both pleasant and unpleasant stimuli. The value of research is that the neuroelectric visualization may be used for receiving useful information relating to the evolution of the aesthetic view of people who perceive the images from simple stimuli to the works of art.

The work of [Tikhomirov et al., 2018] is dedicated to the study of agnosia of visual objects to determine the pathologies of the brain. The visual agnosia has arisen in the case of damage of brain cortex structure responsible for the analysis and synthesis of information thus leading to the violation of the perceptual process and recognition of visual stimuli. The contemporary views about the neuroanatomical and neurophysiological basis of the visual process are described. The medical cases of visual objects agnosia and peculiarities of neuropsycological diagnostics and post-hospital rehabilitation of patients are presented.

The visual objects of different origin such as object images, geometric figures, letters, words and faces with various emotional expressions were used for testing. The basic test models were based on the modified methods of Wundt (Figure 1.1.3(a)), Stroop's method (Figure 1.1.3(b)) and Gottschaldt figures (Figure 1.1.3(c)). The error types, response duration and detection time were evaluated; the recommendations on the diagnostics of visual agnosia in the clinical practice were worked out.

Furthermore, we'll analyze some main concepts relating to the biological evolution of organs of visual sensing, the structural features of the human eye as well as the process of processing and perception of visual information by the brain.

Figure 1.1.3 Examples of interactive realization of basic test models: (a) Wundt's method; (b) interference test by Stroop's method; (c) test by Gottschaldt figures [Tikhomirov et al., 2018].

1.1.2 Light Perception

Photosensitive tissue is present in the simplest organisms. The reaction to light is fundamentally different from the formation of a visual image. The visual structures of the simplest organisms only accumulate light using a photosensitive pigment [Shiffman, 2008]. An eye capable of forming an image appeared in the later stages of evolution. The complex eye of arthropods consists of a bundle of conical elements (ommatidium, Greek - small eye, Figure 1.1.4) containing a lens and a photosensitive pigment [Website istockphoto, 2020]. Each ommatidium registers the incident light from the opposite side, resulting in an image consisting of individual signals. The resulting image is therefore grainy. Such a complex eye is effective in detecting minor changes in the visual field. According to this principle, a complex eye of a fly acts, which is not so easy to catch.

A compound eye is effective for detecting closely spaced objects. The eyes of vertebrates, in contrast to the complex eyes, are perfectly visible at a great distance. The eye of each biological species is maximally adapted to the conditions of its natural habitat and way of life activity.

1.1.3 Vertebrate Eye Anatomy

Anatomically, the eyes of all vertebrates have a similar structure. From fish to mammals, the eyes of all vertebrates have a photosensitive layer, called the retina, and a lens to focus the image on the retina. Figure 1.1.5 presents a vertical section of the human eye.

Figure 1.1.4 Structure of the compound eye of a fly.

The eyeball is located in the deepening of the skull, and has a spherical shape with a diameter of about 20 mm. Outside the eyeball is covered with sclera, a white opaque sheath about 1 mm thick. On the front surface of the eye, the sclera enters the transparent membrane - the cornea. The curved surface of the cornea provides the necessary refractive index (refraction) in the optical system of the eye. It has no blood vessels, it receives nutrients from the capillaries and liquids surrounding it. Light rays are refracted on the cornea and focused by a lens on the retina, located on the back of the eyeball. The vascular membrane of the eye is associated with the sclera, has a thickness of 0.2 mm, and consists of blood vessels that feed the eyes.

The anterior part of the choroid is a colored concentric disc called the iris. From a biological point of view, the iris contains a landscape filled with rings, dashes, specks; each person has more than 200 individual distinguishing features. The iris is a disc-shaped, colored membrane consisting of two smooth muscles, located between the cornea and the lens...