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Behavioral experiments were performed in which rhesus macaques were trained to interact with a computer using a touchscreen. Stimuli consisted of semitone images of Gabor elements with low spatial frequency with different contrast levels. The monkeys’ task was to touch the screen with the paw at the site at which the target stimulus appeared, which was followed by automatic delivery of a food or drink (juice) reward. Contrast was gradually decreased when correct responses were obtained. A two-way forced choice paradigm was used to measure the threshold contrast at which the monkeys could detect the appearance of low-frequency images. Decreases in the spatial frequency of stimuli were accompanied by decreases in contrast sensitivity, while reaction times increased. These data widen our understanding of primate activity in a virtual environment and make it possible to model and study a variety of human diseases.

An image-classification algorithm based on an alphabet of local binary patterns is described. The efficiency of the proposed algorithm is demonstrated using a test image set of handwritten digits (MNIST). A comparison of the algorithm’s properties with similar results to those of convolutional artificial neural networks is presented.

This paper proposes a principle for synthesizing a complex target environment and identifies the optical masking characteristics for unconscious perception of a signal. A signal hidden by masking is supplied on the periphery of the field of view for a short time interval, unconsciously activating wide-angle human “periscopic vision” that possesses low spatial and high temporal resolution. In these studies, the selective attention of the narrow-angle central-vision channel with high spatial resolution was charged with a pseudotarget. We assumed that peripheral vision is capable at that instant of unconsciously perceiving signals hidden by a mask and storing them in memory. It was established that the unconscious low-frequency descriptions of the signals stored in memory influence decision making and control the operator’s involuntary motions under conditions of indeterminacy. Opponent-style implementation of the interaction of central and peripheral vision can serve as a pattern for further refining artificial control systems.

A software–hardware complex for studying the neurophysiological mechanism that controls saccades is described and makes it possible to generate images using the motion of a window synchronized with eye movement. This complex makes it possible to demonstrate to the subject either the part of the image perceived only by the foveal region or the part perceived by the periphery of the retina.

This study investigates the markers of operation of the classification mechanism that is invariant to scale transformations of images of test objects. Observers were asked to classify images according to the criterion of animate/inanimate object. Two series of studies were conducted using the method of cognitive evoked potentials. The angular sizes of the image of the objects presented to the observer were 3° in one series and 0.4° in another. It was established that the classification of the images of the stimuli of various angular sizes according to semantic features (animate/inanimate) causes a difference in the amplitudes of the P200 components (in the leads F7 and F8 of the frontal area). The role of the P200 components of the evoked potentials in the frontal areas of the brain as a marker of the classification process was investigated. It is observed that neural networks of the prefrontal cortex use the invariant description of images implemented in the previous stages of their processing to perform the classification of objects.

This paper discusses the characteristics of eye movement in tasks of recognizing texts and comics with descriptions of dynamic genre scenes. The interconnection of the semantic space of the comics mentally constructed by the observer and the semantic space of test images constructed by the researcher is analyzed by measuring the characteristics of eye movements, which play the role of a distinctive marker that projects onto the test object a subjective algorithm for analyzing the content. The common features inherent to the distribution of saccades and fixations of the gaze in image space when comics and textual images are being experienced probably reflect the algorithm for detecting the semantic, conceptual structure of images common to the analysis of different methods of transferring information in multimedia. This algorithm breaks down under various diseases of the brain. It is assumed that, regardless of the difference of representing information in texts and comics, understanding is provided by common mechanisms for constructing the internal, imaginary, time-varying content.

The interaction between the mechanisms of local and global image analysis at the level of the magnocellular and parvocellular channels of the human visual system was studied. Using wavelet filtering, the spatial frequency composition of texts presented to observers was varied. It was shown that gradual blurring of texts via wavelet filtering interferes with the work of the parvocellular system but simultaneously increases the contribution of the magnocellular system during reading. With an increase in the wavelet element scale, the parvocellular system receives insufficient information for effective work, and in this situation the magnocellular system determines the strategy of eye movements. In addition, the necessary frequency range that ensures the functioning of the reading process is provided.

This paper describes an algorithm for distinguishing between images of two classes of objects: artificial and natural. An approximation to the image is generated using graphical elements similar to the receptor fields of neurons in the primary visual cortex (Zone VI). We show that the approximation-error distribution for natural-object images lies at higher values of the approximation error than that for artificial-object images. This difference makes it possible to detect artificial objects against natural backgrounds.

Electrophysiological studies were performed to measure the threshold (upper end of range) spatial frequency using visual evoked potentials and comparison with visual acuity neuron 26 healthy subjects. The aim of the present work was to create a method for objective measurement of visual acuity. This was addressed by initial measurements using a universally accepted method of visual stimulation and processing of electroencephalograms, which allows errors due to individual differences in visual system function to be minimized. These experiments yielded a strong correlation between the threshold spatial frequency of the test grid yielding an evoked potential on presentation and visual acuity, in degrees, expressed as the resolving ability of the visual system for this optotype. A logarithmic relationship was found between these values and an equation allowing automated calculation of visual acuity (resolving ability) from electrophysiological data was derived. The results were independent of the subject's responses and therefore provides a maximally objective assessment of visual acuity.

The aim of the present work was to assess the range of angular sizes of fragmented images of objects at which perception of the images was scale-independent. Measurements were made of human subjects' recognition thresholds for the shapes of the objects over a wide range of angular sizes (0.19-50 degrees). The experiments used the Gollin test--a method for studying the recognition of fragmented outline images of objects with which the observer is familiar. The results obtained demonstrated that there is a wide range of angular sizes, from 1.0 degrees to 50 degrees, over which the perception thresholds of incomplete outline images do not change with changes in size, along with a narrow range of stimulus sizes, 0.19-1.0 degrees, over which there is a significant size dependence. We suggest that the increase in thresholds and the failure to recognize images of small size occur as a result of an increased contribution of sampling noise at the level of the human retina.

This article gives an analysis of the interconnection of the optical properties of incomplete (fragmented) images and the psychophysical recognition thresholds of objects as necessary conditions for the appearance of visual insight. A well-known method of measuring the perception thresholds of fragmented images—the Gollin test—is proposed for the first time for solving the problem of evaluating the characteristics of insight in a person. The architecture of the neural networks that ensure the appearance of insight is considered.

The work of an operator in solving two classification problems when working with one image alphabet is studied. From ninety visual stimuli, half of the images contained animate objects, and the other half contained inanimate objects. The first task was to classify the images according to a semantic attribute—whether they contained an animate or inanimate object. This alphabet of stimuli was then subjected to wavelet filtering in a low- and high-spatial-frequency region, regardless of semantic significance. The second task was to classify the stimuli according to a physical attribute—a blurred or unblurred object in the image. Electrophysiological monitoring of the operator’s work—recording of the induced visual potentials from the entire surface of the head—made it possible to detect that, from the beginning of the stimulation until the organization of the motor response, parallel processing of the observed signal occurs according to the different semantic and physical attributes. The responses of the temporal and frontal sections of the brain associated with the semantics of the images are distinguished, even under those conditions in which the subject’s task was to classify the physical properties of an image of an object.

It is well known that an important function of binocular vision is to increase the SNR. When a signal simultaneously arrives along two channels, it is summed if the channels are statistically independent. The binocular visual acuity can then theoretically be increased by comparison with the monocular value by a factor of 2, or 1.4. This paper gives the results of experiments to measure the visual acuity by means of Landolt rings. It is established that binocular visual acuity is greater than monocular by a factor of 1.3 on the average. It is assumed that this can be associated with internal multiplicative discretization noise at the level of the retinal receptors. This result is important for understanding image processing in different channels of the visual system.

The methods of neuroiconics and functional magnetic-resonance tomography are used to investigate the factors that limit the possibilities of visual search. The influence of an image of a human face hidden in the background on the activity of the observer’s brain was recorded during the task of tracking a moving ring. It is established that images are unconsciously perceived under threshold-presentation conditions, and this is reflected in the activation of the fusiform gyrus—a region of the brain that participates in face recognition. Under above-threshold presentation conditions, the parietal and frontal regions of the brain were also activated, but activity in this case decreased in the auditory, motor, and certain other regions of the brain not occupied in signal processing. The resulting data reveal the significance of the background semantics under conditions of visual search and explain how the unconsciously perceived optical characteristics of a background image can affect the operator’s functional state.

This paper discusses the process of perceiving dynamic images subjected to processing with spatial-frequency filters that simulate the characteristics of the receptive fields of the neurons of the primary visual cortex. A technique was used that makes it possible to give a quantitative estimate of how subjects perceive the emotional state of people’s faces on images presented to the subjects. It was shown that, besides the vertical and horizontal components of the spatial-frequency spectrum, a substantial role is played by the diagonal components in the process of perceiving the images of faces. Even though the visual system is less sensitive to the diagonal components than to the vertical and horizontal ones, the information contained in them makes it possible to distinguish the individual features and emotional state of a person’s face.

The development of methods of digitally synthesizing and processing images has made it possible to use the methods of iconics to deliberately create test images that selectively activate various structures of the visual system. The methods of processing neurophysiological data, including not only images of the activity of the entire brain but also so-called neuroimaging methods, have made it possible to discriminate the brain structures activated as a result of this selective action. The goal of this study is the spatiotemporal localization (mapping) of the regions of the brain that participate in making decisions concerning the shape of textures. It is established that a subject’s reaction time correlates with the degree of ordering of the textures and with the latency of the late components of the induced potentials in the frontal cortex. The time for a person to make decisions in the task of recognizing a specified class of textures is thereby determined. Mapping of the brain by the method of functional magnetic-resonance tomography showed that the activity of the brain in the process of making decisions involving recognition occurs in the frontal cortex of the human brain.

Various images of the Muller–Lyer figures have been obtained by digital filtering. The filtered images contained a definite spatial-frequency spectrum, predominantly low, medium, or high frequencies. The filtering was carried out by convolution of the images with wavelets that are the difference of two Gaussoids with half-width differing by a factor of 2. The equalization threshold of the Muller–Lyer figures was measured by presenting images subjected to digital processing and without processing, thereby measuring the threshold for bringing about the illusion. The Muller–Lyer illusion was caused by all the stimuli, but it was reliably larger in response to the presentation of the image with a predominantly low-frequency component. The modelling of the Muller–Lyer illusion must take into account the spatial-frequency spectrum of the test image and the characteristics of the pass-band filtering in the spatial-frequency channels of not only the primary but also the higher divisions of the visual system, which construct the envelope based on the primary filtering of the image.