Target Contrast Research Articles

Effects of increased cognitive load on field of view in multi-task operations involving surveillance

Many multi-task operations require human operators to simultaneously perform visual surveillance and a secondary task. As the trend in the technological advancement of surveillance systems indicates high likelihood of heavy interdependence between human and technology in the foreseeable future, it is paramount to venture beyond the context of driving, an area where similar research is saturated in, and investigate the functional field of view (FFoV) of multi-tasking human operators in other operations involving surveillance. In the present study, we investigated the effects of multi-tasking and stimulus parameters (size and contrast) on the response accuracy and response time for identifying visual targets appearing within one’s visual field. Mixed analyses of variance revealed that only response time was negatively affected by multi-tasking, while both response accuracy and response time deteriorated as either the size or contrast of the visual targets decreased. In addition, a significant interaction effect between the investigated parameters of the visual target on response accuracy implies the need for multi-task operations involving surveillance to consider such and future findings critically as they evolve their technology and systems to aid the human operators. The current findings provide insights for surveillance and air traffic control (ATC) operations in future studies.

Refocusing and locating effect of fluorescence scattering field* *Project supported by the National Key Research and Development Program of China (Grant No. 2019YFC0119800), the Youth Talent Support Program of Universities of Hebei Province, China (Grant No. BJ2021038), the National Natural Science Foundation of China (Grant No. 12004265), the Natural Science Foundation of Hebei Province, China (Grant No. A2020210001), and the

Optical imaging deep inside scattering medium has always been one of the challenges in the field of bioimaging, which significantly drawbacks the employment of con-focal microscopy system. Although a variety of feedback techniques, such as acoustic or nonlinear fluorescence-based schemes have realized the refocusing of the coherent light, the problems of non-invasively refocusing and locating of linearly-excited fluorescent beads inside the scattering medium have not been thoroughly explored. In this paper, we linearly excited the fluorescent beads inside a scattering medium by using our homemade optical con-focal system, collected the fluorescence scattering light as the optimized target, and established a theoretical model of target contrast enhancement, which is consistent with the experimental data. By improving both the cost function and variation rate within the genetic algorithm, we could refocus the fluorescence scattering field while improving the contrast enhancement factor to 12.8 dB. Then, the positions of the fluorescent beads are reconstructed by subpixel accuracy centroid localization algorithm, and the corresponding error is no more than 4.2 μm with several fluorescent beads within the field of view. Finally, the main factors such as the number of fluorescent beads, the thickness of the scattering medium, the modulating parameter, the experimental noise and the system long-term stability are analyzed and discussed in detail. This study proves the feasibility of reconstructing fluorescent labeled cells inside biological tissues, which provides certain reference value for deep imaging of biological tissues.

Preparation of Novel Bi-Modal Nano Contrast Agent and Its Application in Diagnosis of Breast Cancer

In the study, a new ultrasound contrast agent was used in the above diagnosis. Specifically, PLGA nanoparticles (PNA) loaded with Au nanorods and perfluorohexane (PFH) were prepared by the double emulsification method, and then the aptamer (APT) and PNA were connected by the carbodiimide method to obtain dualmodal ultrasound/photoacoustic targeting contrast agent (APT-PNA). Subsequently, physical characterization was performed on the prepared material, and then a fluorescence microscope was used to detect in vitro binding to breast cancer MCF-7 cells, with the normal nanoparticle group, HELA cell group, and APT interference group as controls. On this basis, it was used for the SLNB of breast cancer patients. The results showed that, the average particle size of APT-PNA was (468.5±23.6) nm, and the connection rate between the APT and the PNA reached 95.68%. After laser irradiation, the photo-induced phase changes of the APT-PNA were obvious. The APT-PNA aggregated around and bound firmly to breast cancer MCF-7 cells, while other control groups did not show obvious specific binding. After using APT-PNA, the ultrasound signal and photoacoustic signal were obviously enhanced than before irradiation. Of the 40 patients who participated in the trial, 37 developed lymphatic imaging, with an imaging rate of 92.5%, and 32 of the 37 patients with lymphatic imaging developed lymph node imaging, with a success rate of 86.5%.

The Impact of LED Colour Rendering on Reaction Time of Human Eyes in Tunnel Interior Zone

The long reaction time of human eyes will increase the probability of traffic accidents in tunnels which can be reduced by improving lighting conditions. In recent years, light-emitting diodes (LEDs) have replaced the traditional lighting source in a tunnel. Colour rendering index 2012 (CRI2012, a colour rendering evaluation index) is the most suitable evaluation method for colour rendering of LEDs. In order to study the impact of colour rendering of LEDs on the reaction time of human eyes, a driving simulation environment was designed. First, three CCTs (correlated colour temperatures), four CRI2012s, and eight colours of targets were assessed using mesopic photometry model MES-2. The calculation results indicated that the contrast of targets had a positive correlation with CRI2012 and had a negative correlation with CCT. Then, reaction time experiment was conducted in simulated tunnel environments. There are 30 observers who participated. The results show that the LEDs with higher CRI2012 and lower CCT in tunnel is conducive to reducing the reaction time of human eyes. High CRI2012 enables drivers to accurately and quickly identify colours. This paper provides a reference for the design of light source parameters, roads, walls, and warning signs in the tunnel.

Targeting Contrast Agents With Peak Near-Infrared-II (NIR-II) Fluorescence Emission for Non-invasive Real-Time Direct Visualization of Thrombosis.

Thrombosis within the vasculature arises when pathological factors compromise normal hemostasis. On doing so, arterial thrombosis (AT) and venous thrombosis (VT) can lead to life-threatening cardio-cerebrovascular complications. Unfortunately, the therapeutic window following the onset of AT and VT is insufficient for effective treatment. As such, acute AT is the leading cause of heart attacks and constitutes ∼80% of stroke incidences, while acute VT can lead to fatal therapy complications. Early lesion detection, their accurate identification, and the subsequent appropriate treatment of thrombi can reduce the risk of thrombosis as well as its sequelae. As the success rate of therapy of fresh thrombi is higher than that of old thrombi, detection of the former and accurate identification of lesions as thrombi are of paramount importance. Magnetic resonance imaging, x-ray computed tomography (CT), and ultrasound (US) are the conventional non-invasive imaging modalities used for the detection and identification of AT and VT, but these modalities have the drawback of providing only image-delayed indirect visualization of only late stages of thrombi development. To overcome such limitations, near-infrared (NIR, ca. 700–1,700 nm) fluorescence (NIRF) imaging has been implemented due to its capability of providing non-invasive real-time direct visualization of biological structures and processes. Contrast agents designed for providing real-time direct or indirect visualization of thrombi using NIRF imaging primarily provide peak NIR-I fluorescence emission (ca. 700–1,000 nm), which affords limited tissue penetration depth and suboptimal spatiotemporal resolution. To facilitate the enhancement of the visualization of thrombosis via providing detection of smaller, fresh, and/or deep-seated thrombi in real time, the development of contrast agents with peak NIR-II fluorescence emission (ca. 1000–1,700 nm) has been recently underway. Currently, however, most contrast agents that provide peak NIR-II fluorescence emissions that are purportedly capable of providing direct visualization of thrombi or their resultant occlusions actually afford only the indirect visualization of such because they only provide for the (i) measuring of the surrounding vascular blood flow and/or (ii) simple tracing of the vasculature. These contrast agents do not target thrombi or occlusions. As such, this mini review summarizes the extremely limited number of targeting contrast agents with peak NIR-II fluorescence emission developed for non-invasive real-time direct visualization of thrombosis that have been recently reported.

Aberrant Hemispheric Asymmetry to a Contrast Illusion is Associated With Schizophrenia: A Principal Component Analysis of Event Related Potentials

The contrast of a visual target can appear suppressed in the presence of surrounding stimuli—an illusion that is sensitive to similarity between center and surround (e.g. their relative orientation; aka orientation dependent surround suppression [ODSS]). Evidence suggests that patients with schizophrenia have reduced ODSS relative to healthy controls (HC). The present study examined differences in neurophysiological response between SZ and HC during an ODSS task.

Overnight Consolidation of Speech Sounds Predicts Decoding Ability in Skilled Adult Readers

ABSTRACT Phonological representations are important for reading. In the current work, we examine the relationship between speech-perceptual memory encoding and consolidation to reading ability in skilled adult readers. Seventy-three young adults (age 18–24) were first tested in their word and nonword reading ability, and then trained in the late evening to identify an unfamiliar speech sound contrast (Hindi retroflex-dental). Participants were assessed in their ability to perceive the target contrast immediately before training, after training, and 12 hours later. While perceptual performance on the target at any time point was unassociated with reading ability, overnight changes to the post-training perceptual ability over the 12-hour delay were significantly associated with nonword reading (i.e. decoding) ability, but not real-word reading. These results provide preliminary support for the hypothesis that individual differences in memory processes that update phonological representations following acoustic-phonetic exposure relate to decoding performance, including in adulthood.

Ultra-high-frequency radio-frequency acoustic molecular imaging with saline nanodroplets in living subjects.

Molecular imaging is a crucial technique in clinical diagnostics, but it relies on radioactive tracers or high magnetic fields that are unfavorable for many patients, particularly infants and pregnant women. Ultra-high-frequency-radiofrequency-acoustic (UHF-RF-acoustic) imaging using non-ionizing RF pulses allows deep-tissue imaging with sub-millimeter spatial resolution. However, lack of biocompatible and targetable contrast agents has prevented the successful in vivo application of UHF-RF-acoustic imaging. Here, we report our development of targetable nanodroplets for UHF-RF-acoustic molecular imaging of cancers. We synthesize all-liquid nanodroplets containing hypertonic saline that are stable for at least 2 weeks and can produce high intensity UHF-RF-acoustic signals. Compared with concentration-matched iron-oxide nanoparticles, our nanodroplets produce at least 1600 times higher UHF-RF-acoustic signals at the same imaging depth. We demonstrate in vivo imaging using the targeted nanodroplets in a prostate cancer xenograft mouse model expressing gastrin release protein receptor (GRPR), showing targeting specificity by more than two-fold, compared to untargeted nanodroplets or prostate cancer cells not expressing GRPR.

MRzero - Automated discovery of MRI sequences using supervised learning.

A supervised learning framework is proposed to automatically generate MR sequences and corresponding reconstruction based on the target contrast of interest. Combined with a flexible, task-driven cost function this allows for an efficient exploration of novel MR sequence strategies. The scanning and reconstruction process is simulated end-to-end in terms of RF events, gradient moment events in x and y, and delay times, acting on the input model spin system given in terms of proton density, and , and . As a proof of concept, we use both conventional MR images and maps as targets and optimize from scratch using the loss defined by data fidelity, SAR penalty, and scan time. In a first attempt, MRzero learns gradient and RF events from zero, and is able to generate a target image produced by a conventional gradient echo sequence. Using a neural network within the reconstruction module allows arbitrary targets to be learned successfully. Experiments could be translated to image acquisition at the real system (3T Siemens, PRISMA) and could be verified in the measurements of phantoms and a human brain in vivo. Automated MR sequence generation is possible based on differentiable Bloch equation simulations and a supervised learning approach.

Detecting Small Size and Minimal Thermal Signature Targets in Infrared Imagery Using Biologically Inspired Vision.

Thermal infrared imaging provides an effective sensing modality for detecting small moving objects at long range. Typical challenges that limit the efficiency and robustness of the detection performance include sensor noise, minimal target contrast and cluttered backgrounds. These issues become more challenging when the targets are of small physical size and present minimal thermal signatures. In this paper, we experimentally show that a four-stage biologically inspired vision (BIV) model of the flying insect visual system have an excellent ability to overcome these challenges simultaneously. The early two stages of the model suppress spatio-temporal clutter and enhance spatial target contrast while compressing the signal in a computationally manageable bandwidth. The later two stages provide target motion enhancement and sub-pixel motion detection capabilities. To show the superiority of the BIV target detector over existing traditional detection methods, we perform extensive experiments and performance comparisons using high bit-depth, real-world infrared image sequences of small size and minimal thermal signature targets at long ranges. Our results show that the BIV target detector significantly outperformed 10 conventional spatial-only and spatiotemporal methods for infrared small target detection. The BIV target detector resulted in over 25 dB improvement in the median signal-to-clutter-ratio over the raw input and achieved 43% better detection rate than the best performing existing method.

MustGAN: multi-stream Generative Adversarial Networks for MR Image Synthesis.

Multi-contrast MRI protocols increase the level of morphological information available for diagnosis. Yet, the number and quality of contrasts are limited in practice by various factors including scan time and patient motion. Synthesis of missing or corrupted contrasts from other high-quality ones can alleviate this limitation. When a single target contrast is of interest, common approaches for multi-contrast MRI involve either one-to-one or many-to-one synthesis methods depending on their input. One-to-one methods take as input a single source contrast, and they learn a latent representation sensitive to unique features of the source. Meanwhile, many-to-one methods receive multiple distinct sources, and they learn a shared latent representation more sensitive to common features across sources. For enhanced image synthesis, we propose a multi-stream approach that aggregates information across multiple source images via a mixture of multiple one-to-one streams and a joint many-to-one stream. The complementary feature maps generated in the one-to-one streams and the shared feature maps generated in the many-to-one stream are combined with a fusion block. The location of the fusion block is adaptively modified to maximize task-specific performance. Quantitative and radiological assessments on T1,- T2-, PD-weighted, and FLAIR images clearly demonstrate the superior performance of the proposed method compared to previous state-of-the-art one-to-one and many-to-one methods.

An In-Flight Radiometric Calibration Method Considering Adjacency Effects for High-Resolution Optical Sensors Over Artificial Targets

When using a field calibration site to perform in-orbit radiometric calibration of a space-borne remote sensor, the measured signal by the sensor may contain radiation from adjacent pixels, due to scattering in the Earth’s atmosphere and the sensor viewing characteristics. If this is not accounted for in the modeling, the accuracy of the radiometric calibration will be reduced. Nonuniformities of the ground target are more significant for the calibration of high-resolution sensors. In addition, if the brightness contrast of neighboring targets is not small, the impact of the adjacency effects will be more significant. It is important to quantitatively analyze and estimate the influence of this kind of adjacency effects, to reduce the uncertainty of in-orbit radiometric calibration. To evaluate the adjacency effects caused by atmospheric multiple scattering, this article constructed a local atmospheric point spread function model using long time-series satellite-ground synchronous observation data and developed an adjacency effects simulation method, which considers background reflectance spectral information. Tests on Sentinel-2A and Worldview-3 imagery overpassing the Baotou calibration and validation site (Baotou C&V site) (China) indicate that the proposed modeling method can effectively account for the influence of the adjacency effects in vicarious calibration. Uncertainties of relevant parameters and their contributions to the calibration result were also analyzed, and uncertainty assessment results show that the vicarious radiometric calibration scheme considering adjacency effects correction can bring about a total uncertainty less than 7%.

T2-Weighted and Ultra-short TE Molecular Magnetic Resonance Imaging for Gastric Cancer Diagnosis using Polymer-based Magnetic Nanoparticles

Several recently developed technologies for molecular imaging have been applied to magnetic resonance (MR) imaging for cancer. In particular, various MR sequences with biocompatible polymer-based magnetic nanoparticles (pMNPs) have been applied for the MR imaging of cancer. However, there are several limitations to this approach, and passive contrast agents are not yet sufficiently targeted. This is a particular challenge for gastric cancer owing to the interference from stomach contents. Therefore, in this study we developed targeting contrast agent and assessed its feasibility for early gastric cancer diagnosis using a mouse model. Specifically, we synthesized pMNPs, which enable both T2-weighted (T2) and ultra-short TE (UTE) MR imaging using hyaluronic acid as the polymer, which binds to the receptor CD44, a recently identified biomarker of gastric cancer. Both MR sequences (T2, UTE) were analyzed with respect to imaging effects and targeting to the pMNPs. In vitro assessments showed no significant cytotoxicity of the pMNPs to MKN-45 and MKN-28 cells and confirmed the cellular uptake of the pMNPs. MR signal enhancement was identified after pMNPs injection to the mice, and the pMNPs gradually accumulated in the tumors. Based on the results, we suggest that pMNPs serve as useful probes for imaging stem-like cancer cells, and can further provide new possibilities by simultaneously confirming T1 and T2 MR imaging effects.

Effect of Aniseikonia Induced by a Size Lens on Contrast Visual Acuity and Stereo Acuity and Eye-hand Coordination

Purpose : The purpose of this study is to find out the effect of unequal vision induced by a size lens on contrast visual acuity, and distance and near stereo acuity.Methods : Thirty people in their 20s and 30s were involved to measure for high and low contrast visual acuity, distance stereo acuity and near stereo acuity according to the magnification of 2, 4, and 6% of the size lens. Contrast visual acuity composed of a Randolt ring was measured using LogMAR visual acuity, and it was divided into high contrast (100%) and low contrast (25, 10%) visual acuity according to the contrast of the target. The distance stereo acuity was measured using a three-rod test, and the near stereo acuity was measured using a random dot test. For eyehand coordination, a device made with a t-wall as a motif was used.Results : Contrast visual acuity did not show any significant difference after 2% aniseikonia induction, but showed a significant difference and a decrease at 4 and 6% aniseikonia induction (p<0.050). Contrast visual-acuity decreased significantly as the degree of aniseikonia increased, and as the degree of contrast decreased. The distance and near stereo-acuity showed a significant difference and decreased when the aniseikonia of 4 and 6% was induced, except for the aniseikonia of 2% (p<0.050). Eye-hand coordination decreased significantly with increasing aniseikonia (p<0.050).Conclusion : It was identified that as the aniseikonia increased, contrast visual-acuity, stereo-acuity and the capability of eye-hand coordination were decreased. In clinical practice, aniseikonia should be considered when an optician prescribes aniseikonia. However, if the prescription is avoided in consideration of aesthetics, the difference in magnification must be induced to within 2%. Therefore, it is expected that it will contribute to improving the health and quality of life by preventing the factors deteriorating daily life that can be caused by aniseikonia.

Manganese-Based Targeted Nanoparticles for Postoperative Gastric Cancer Monitoring via Magnetic Resonance Imaging.

Postoperative recurrence is a common and severe problem in the treatment of gastric cancer; consequently, a prolonged course of chemotherapy treatment is inevitable. Monitoring by imaging could provide an accurate evaluation of the therapeutic effects, which would be beneficial to guide a treatment strategy adjustment over time. However, current imaging technologies remain insufficient for the continuous postoperative monitoring of gastric cancer. In this case, molecular imaging offers an efficient strategy. Targetable contrast agents are an essential part of molecular imaging, which could greatly enhance the accuracy and quality of monitoring. Herein, we synthesized a Mn-based contrast agent for magnetic resonance imaging (MRI) of gastric cancer monitoring. Initially, small-sized Mn3O4 nanoparticles (NPs) were synthesized. Then, a functionalized polyethylene glycol (PEG) lipid was attached to the surface of the Mn3O4 NPs, to improve biocompatibility. The targetable MRI contrast agent (Mn3O4@PEG-RGD NPs) was further prepared by the conjugation of the arginine-glycine-aspartic acid (RGD) peptides. The completed Mn3O4@PEG-RGD NPs had the small size of 7.3 ± 2.7 nm and exhibited superior colloidal stability in different solution environments. In addition, Mn3O4@PEG-RGD NPs exhibited reliable biotolerance and low toxicity both in vitro and in vivo. Imaging experiments amply demonstrated that Mn3O4@PEG-RGD NPs could efficiently accumulate in gastric cancer tissues and cells via RGD mediation, and immediately significantly increased the MRI effects. Through this study, we can conclude that Mn3O4@PEG-RGD NPs have the potential to be a novel MRI contrast agent for the postoperative monitoring of gastric cancer.

Ensemble coding of color and luminance contrast.

Ensemble coding has been demonstrated for many attributes including color, but the metrics on which this coding is based remain uncertain. We examined ensemble percepts for stimulus sets that varied in chromatic contrast between complementary hues, or that varied in luminance contrast between increments and decrements, in both cases focusing on the ensemble percepts for the neutral gray stimulus defining the category boundary. Each ensemble was composed of 16 circles with four contrast levels. Observers saw the display for 0.5 s and then judged whether a target contrast was a member of the set. False alarms were high for intermediate contrasts (within the range of the ensemble) and fell for higher or lower values. However, for ensembles with complementary hues, gray was less likely to be reported as a member, even when it represented the mean chromaticity of the set. When the settings were repeated for luminance contrast, false alarms for gray were higher and fell off more gradually for out-of-range contrasts. This difference implies that opposite luminance polarities represent a more continuous perceptual dimension than opponent-color variations, and that "gray" is a stronger category boundary for chromatic than luminance contrasts. For color, our results suggest that ensemble percepts reflect pooling within rather than between large hue differences, perhaps because the visual system represents hue differences more like qualitatively different categories than like quantitative differences within an underlying color "space." The differences for luminance and color suggest more generally that ensemble coding for different visual attributes might depend on different processes that in turn depend on the format of the visual representation.

A bio-inspired spatiotemporal contrast operator for small and low-heat-signature target detection in infrared imagery

Thermal infrared imaging is a promising modality for long-range small target detection. However, low target contrast, high background clutter and sensor noise are some of the key challenges that need to be resolved efficiently for robust detection performance. The spatiotemporal processing in the early stages of the visual pathway of small flying insects has a remarkable ability to simultaneously address such challenges. The first stage of the early visual system corresponds to the adaptive temporal filtering mechanisms of photoreceptor cells. This stage improves the signal-to-noise ratio, enhances target background discrimination and compresses the signal bandwidth. The second stage pertains to the adaptive spatiotemporal filtering in the lamina monopolar cells. This stage removes spatiotemporal redundancy and enhances target contrast. In this paper, we explore such two-stage bio-processing to simultaneously suppress clutter and enhance the contrast of small low-heat-signature targets in real-world infrared imagery. We also propose a simple and efficient spatial contrast operator called center–surround total differential index for target region segmentation. Small moving target detection experiments on real-world high-bit-depth infrared video sequences show that the proposed method significantly outperforms the state-of-the-art spatial and spatiotemporal infrared small target detection methods. Specifically, our method resulted in 59% better detection rate (at 10 $$^{-5}$$ false alarm rate) than the best competing method. Our results show that the bio-inspired spatiotemporal preprocessing is an excellent tool for significantly improving the performance of existing long-range infrared target detection techniques.

Distorted optical input affects human perception

Collinear facilitation, the mechanism for grouping contour elements, is a process involving lateral interactions that improve the detectability of a target by the presence of collinear flankers. It was shown that the development of collinear facilitation is experience dependent and that it may be impaired when the visual input is distorted in one meridian (meridional amblyopia). In oblique astigmatism, the blurring is on the opposite oblique meridian in both eyes, resulting in two conflicting images, which may affect the development of binocular vision. We hypothesized that the collinear facilitation of adults with oblique astigmatism is reminiscent of the abnormal development of the lateral facilitation of meridional amblyopia. We explored the perception of binocular vision and collinear facilitation in cases of both distorted and non-distorted vision. Fully corrected participants that tested for the target contrast detection of Gabor patches and two collinear flankers, presented for 80 ms, were positioned at different orientations (0° (180°), 45°, 90°, and 135°) and for different eyes (monocular, binocular). The results show a significant anisotropy for monocular collinear facilitation between the blured and the clear meridians, being lower in the blurriest meridian than in the clearest meridian, resembling the meridional amblyopia results. Collinear facilitation results in poor binocular summation between the monocular channels. Our results indicate that the perceptual behavior was similar to that of meridional amblyopic subjects having an anisotropy of collinear facilitation between cardinal meridians in oblique astigmatic subjects.

Spatial uncertainty improves the distribution of visual attention and the availability of sensory information for conscious report.

Picking-up and exploiting spatial and temporal regularities in the occurrence of sensory events is important for goal-directed behaviour. According to the "Predictive Coding Hypothesis" (Friston Philosophical Trans R Soc B 360(1456):815-836, 2005), these regularities are used to generate top-down predictions that are constantly compared with actual sensory events. In a previous study with the Attentional Blink (AB) paradigm, we showed that the temporal and probabilistic uncertainty of T2s that are presented outside the Attentional Blink period, i.e. at least 400ms after T1, improves the conscious report of T2 that are presented inside the AB. The study of ERP correlated showed that this improvement was associated with a prolonged storage of pre-conscious T2 traces in extra-striate areas (Lasaponara et al. Cortex 71:15-33, 2015). Here, we tested whether variations in the probabilistic cueing of the position of a primary T1 visual target in a 4 × 4 letter array, modulate the retention of memory traces evoked by secondary letter targets (T2) that were presented in other positions of the array. Most important, in each trial, the identity of T2 was specified to participants upon disappearance of the array. We show that high probabilistic cueing facilitates T1 detection and improves the corresponding sensitivity index (d'). In contrast, retention and conscious report of secondary targets (T2) improves when the probabilistic cueing of T1 position is poor. These results suggest that uncertainty in the upcoming position of primary targets boosts the strength of memory traces evoked by secondary targets and improves the possibility that traces of secondary targets gain full access to conscious processing.

Multi-target visual recognition and positioning methods for sorting robots

Aiming at the problems of complex shape and random placement of sorting robots, this paper proposes a multi-objective visual recognition and positioning methods for sorting robots. A sorting robot system with visual perception was constructed,which based on the four-degree-of-freedom DOBOT robot. What’s more, the visual system acquires images of multiple targets on the conveyor belt, the image preprocessing algorithm improves the contrast of the sorting targets, thus circular and linear structural elements are constructed in order to fill and smooth the multi-target regions segmented by the largest inter-class variance method. Besides, Establishing centroid coordinates based on image information to identify and locate connected domains of multi-target regions. The experimental results show that the method can achieve statistics on the number of multi-targets. On the basis of the hand-eye calibration of the sorting robot, the multi-objects with complex shapes and random positions are identified and positioned, and the positional information provides the autonomous grasping and sorting for the sorting robot.