Digital Video Analysis Research Articles

Digital video analysis reveals gait parameters that predict performance in the jumping test phase of three-day eventing

In international equestrian sport, visual inspections assess gait and lameness to protect the welfare of performance horses during competition. Horses competing internationally in three-day eventing must pass two mandatory inspections (pre-competition and post-cross country) before attempting the final phase: the jumping test (JT). We hypothesized that digitally quantifying objective gait parameters captured during the two mandatory inspections will identify locomotor characteristics that predict success during the jumping test. Utilizing the DeepLabCut (DLC) software package for labeling of anatomical landmarks and a custom analysis pipeline we calculated gait parameters for 194 competition horses at the trot. During the pre-competition inspection, relative trot speed was significantly associated (P = 0.0060, GLMM), and the forelimb travel trended towards significance (P =0.0800, GLMM), with achieving a clear round in the later jumping test. Post-cross country, the forelimb travel significantly predicted JT results (P = 0.0188, GLMM). As our parameters are scaled for body size, these parameters may indicate conformational characteristics for superior jumping ability and overall athletic fitness. Within each competitive effort, comparisons of the post-cross country and pre-competition observations revealed that the change in speed and duty factor were significantly different in the group that accrued jumping faults (P = 0.00376 and P = 0.02430, GLMM), perhaps capturing locomotor signs of exercise fatigue. Further work employing these approaches to better understand competition performance will encourage the use of objective measures to protect sport horse welfare, as well as provide an advantageous tool for gait evaluation in the horse.

Forensic integrity verification of video recordings based on MTS files.

Digital video is used in criminal trials as evidence with legal responsibility because video content vividly depicts events occurring at a crime scene. However, using sophisticated video editing software, assailants can easily manipulate visible clues for their own benefit. Therefore, the integrity of digital video files acquired or submitted as evidence must be ensured. Forensic analysis of digital video is key to ensuring the integrity of links with individual cameras. In this study, we analyzed whether it is possible to ensure the integrity of MTS video files. Herein, we propose a method to verify the integrity of MTS files encoded by advanced video coding high definition (AVCHD), which is frequently used for video recording. To verify MTS file integrity, we propose five features. Codec information, picture timing, and camera manufacture/model are modified AVI and MP4-like format video verification features. Group of pictures and Universally Unique Identifier patterns were specifically developed for MTS streams. We analyzed the features of 44 standard files recorded using all recording options of seven cameras. We checked whether integrity can be validated on unmanipulated videos recorded in various environments. In addition, we considered whether manipulated MTS files edited in video editing software could be validated. Experimental results show that all unmanipulated and manipulated MTS files with known recording devices were discriminated only when all five features were checked. These results show that the proposed method verifies the integrity of MTS files, strengthening the validity of MTS file-based evidence in trials.

Using Digital Video Analysis to Develop Elementary Education Majors’ Noticing Skills in Elementary Physical Education

Preparing future teachers is a complex endeavor, yet there are tools that help prepare preservice teachers (PST). One tool is digital video (DV). DV provides opportunities for PST to see and hear themselves teach and make the needed corrections in their lessons and activities. This study examined the accounts of elementary education majors’ experiences with DV self-analysis and how these related to noticing skills in their teaching elementary physical education lessons. The PST benefited from noticing themselves teach and that DV is an appropriate tool in the preparation of PST.

Politics through machine eyes: What computer vision allows us to see

Computer vision techniques have recently burst onto the scene in visual political communication research, dramatically extending the scope of digital image and video analysis. Over the last five years, in particular, papers featuring computational methods have grown in frequency and breadth, appearing in a variety of journals across different disciplines, ranging from the digital humanities and social semiotics to political communication and data science. Topics have been equally expansive and include large scale examinations of political protest, candidate self-presentation style and partisan symbolism, affective polarization, gender stereotypes, debate performances and voter impression formation, public policy, electoral fraud, and topics outside of conventional politics such as extremist propaganda. In this article, each of these areas of investigation are briefly reviewed for the insights they are revealing about political visuals as well as the tools and techniques employed. Ethical considerations are also explored to highlight some of the tradeoffs inherent in research involving computational analysis of political visuals.

A Pilot Trial of Dopamine Replacement for Dynamic Facial Expressions in Parkinson's Disease.

Current conflict exists regarding the potential beneficial effects of dopamine medications on facial expressivity in Parkinson's disease. Via digital video analysis software, we previously found reduced facial movement (entropy) and slower time to reach peak entropy in individuals with Parkinson's disease compared to controls. We aimed to determine whether levodopa medications improved parameters of dynamic facial expressions (amplitude, speed). A total of 34 individuals with idiopathic Parkinson's disease were videotaped making voluntary facial expressions (happy, fear, anger, disgust) when "on" and "off" levodopa. Participants were 52 to 80 years old, early to mid-stage disease, non-demented, and included more men (65%). Expressions were digitized and analyzed using software that extracted three variables: two indices of movement change (total entropy, percent entropy change) and time to reach peak expression. Indices of facial movement (total entropy, peak entropy) and timing were significantly improved when patients were "on" vs "off" medication (all F's ≥ 3.00, P < 0.05). For total movement and time to reach peak entropy, levodopa-related improvements were emotion nonspecific. Levodopa-related improvement for peak entropy was driven primarily by happy expressions. There was no relationship between quantitative indices and clinical measures of mood (depression, anxiety) and motor disease severity. The effects of levodopa on Parkinson's disease voluntary facial movement and on timing were robust and consistent with those of levodopa on other intentional movements in Parkinson's disease. This improvement possibly occurred because of levodopa enhanced activation of face representation areas in fronto-cortical regions or because of less movement-based suppression.

Behavioral disturbances induced by cyanobacterial oligopeptides microginin-FR1, anabaenopeptin-A and microcystin-LR are associated with neuromotoric and cytotoxic changes in Brachionus calyciflorus

Aquatic animals are exposed to various cyanobacterial products released concomitantly to the environment by decaying blooms. Although there exist results on the toxicity of cyanobacterial extracts little is known on the influence of pure oligopeptides or their mixtures and elucidated mechanisms of behavioral toxicity in zooplanktonic organisms. Therefore, the aim of the present study was to assess the effects of single and mixed pure cyanobacterial oligopeptides: microginin FR-1 (MG-FR1), anabaenopeptin-A (ANA-A) and microcystin-LR (MC-LR) at various concentrations on the swimming behavior and catecholamine neurotransmitter activity, muscular F-actin structure, DNA nuclear content and cell viability of a model rotifer Brachionus calyciflorus. Swimming behavior was analyzed with the use of video digital analysis. Fluorescent microscopy imaging was used to analyze neuromotoric biomarkers in the whole organisms: neuromediator release (by staining with EC517 probe), muscle F-actin filaments (by staining with blue phalloidin dye). DNA content and cytotoxicity was also determined by Hoechst 34580 and propidium iodide double staining, respectively. The results showed that single oligopeptides inhibited all the tested endpoints. The binary mixtures induced synergistic interaction on swimming speed except for MG-FR1 +MC-LR which was nearly additive. Both binary and ternary mixtures also synergistically degraded F-actin and triggered cytotoxic effects visible in the whole organisms. Antagonistic inhibitory effects of all the binary mixtures were found on catecholamine neurotransmitter activity, however the ternary mixture induced additive toxicity. Antagonistic effects of both binary and ternary mixtures were also noted on nuclear DNA content. The results of the study suggest that both depression of neurotransmission and impairment of muscle F-actin structure in muscles may contribute to mechanisms of Brachionus swimming speed inhibition by the tested single cyanobacterial oligopeptides and their mixtures. The study also showed that natural exposure of rotifers to mixtures of these cyanobacterial metabolites may result in different level of interactive toxicity with antagonistic, additive synergistic effects depending on the variants and concentrations present in the environment.

Kinematics comparison of squat (2D vs 3D analysis) for remote learning – pilot study

Bodyweight squats are a common exercise in athletic training and rehabilitation due to their biomechanical and neuromuscular similarities to fundamental movements in a variety of sports and their requirements of coordination of major joints and numerous muscle groups (Schoenfeld, 2010). They are essential for kinesiology students, whose future careers often include athletic training and rehabilitation, to learn how to analyze the kinematics of a squat. While 3D movement analysis is considered the gold standard for motion capture (Chung &amp; Ng, 2012), 2D digital video analysis is more commonly chosen in education environments to provide hands-on experience. However, few studies have investigated the differences between 2D and 3D analysis of squats (Escamilla et al., 2001; Krause et al., 2015; Schmitz et al., 2015). Therefore, the current study aims to compare 2D and 3D measurements of narrow-stance squats while enhancing learning by engaging students with hands-on experience using free, open-source software. Fifteen healthy adults (nine females, six males, 26.93 ± 9.04 years old) participated in this study. Following proper COVID safety guidelines, 2D analyses were performed by undergraduate students at home while 3D analyses were performed using a motion capture system in the laboratory. Lower extremity joint angles and displacements were calculated using 2D and 3D methods. Statistical significances were found when comparing the differences between both measurements except for hip flexion. Nonetheless, the resulting angular and linear measurements from both 2D and 3D analyses aligned with previous research, suggesting that 2D digital video analysis is a viable option for educational purposes despite the significant differences.

Synergistic toxicity of some cyanobacterial oligopeptides to physiological activities of Daphnia magna (Crustacea)

Anabaenopeptins and microcystins are oligopeptides produced by bloom-forming cyanobacteria. We determined in vivo effects of anabaenopeptin-B (AN-B) and two variants of microcystins of different hydrophobicity (MC-LR and MC-LF) on the physiology of Daphnia magna. Heart rate, thoracic limb activity and post-abdominal claw activity were determined by digital video analysis and oxygen consumption by Oxygraph + system. EC50 calculation and isobole methodology for interactive effects of AN-B and MC-LR mixture were used.Daphnids' responses to all three oligopeptides were concentration- and time-dependent. MC-LF was the most potent inhibitor of heart rate, thoracic limb activity, post-abdominal claw activity and oxygen consumption. AN-B was more toxic than MC-LR toward oxygen consumption; it inhibited the movements of limbs and post-abdominal claw similarly to MC-LR, but did not inhibit heart rate. The strongest toxic effects were induced by the binary mixture of AN-B with MC-LR at the sum concentration equal to the concentration of the single compounds. First time direct synergistic toxic effects of the cyanopeptides on all the physiological parameters were found. The obtained results explain stronger disturbances in aquatic organisms caused by cyanobacterial cell contents than the individual cyanopeptides present even at higher concentrations. Other metabolites and their interactions need further studies.

39 Using artificial intelligence to analyze horse gait parameters for genomics research in musculoskeletal traits

Arguably the most important factors considered when assessing elite performance horses, traits of “lameness susceptibility” and “gait quality” lack objective and quantitative measures. Popular qualitative approaches to determine lameness or gait quality do not provide accurate measures amenable to genetic study, nor can producers easily apply them. However, digital video analysis of gait utilizing recently developed artificial intelligence based approaches holds significant promise to meet these industry needs. It also provides quantitative endophenotypes, the comparison of behavior to phenotypes through genetic correlation, with sufficient precision for genome-wide association studies. Here we describe pilot work using consumer level digital video cameras to capture high-resolution and high speed videos of horses at the trot during mandatory veterinary inspection for Fédération Équestre Internationale (FEI) level competitions. Twenty-three key skeletal landmarks, selected based on gait mobility, on each horse in 20 different frames of the video are labeled with DeepLabCut, a software package applying a deep neural network approach for object recognition in the frame image. Raw quantitative gait parameters such as stride length, stance time, and angular range of the fetlock joint were derived from the landmark tracking data by a robust data processing pipeline. The pipeline comprises many operations, including outlier removal due to occlusion, trajectory smoothing, model-fitting-based phase identification, and gait parameters calculation. The ease of video capture allowed for 1,597 samples of 945 horse and rider combinations from 5 FEI competitive levels within the same discipline of eventing to be captured from just 6 competitions around the southeast US, before closing of travel due to the pandemic. The current training run was applied to 1,280 frames from 64 videos with 23 landmark points plotted per frame. This training will be applied to our database of 1,533 additional videos allowing gait parameter analysis for horses exhibiting 3–5 trot strides in a single direction. Future work will incorporate additional trot strides, both directions of travel, and enlarging our sampling of horses. This database will be used in future applications in animal selection and lameness diagnosis, as well as in construction of quantitative performance traits suitable for genomics research.

141 Locomotion pattern analysis using digital video labeling by machine learning

The assessment of lameness has long relied on the expertise of a human observer. Innovations in technology have provided new options to objectively detect lameness, but most systems involve equipment attached to the horse, potentially causing changes in their normal locomotion patterns. One such tool, the Lameness Locator, analyzes motion data recorded by accelerometers mounted to the horse with bandages, stickers or hats. Tactile sensors in horse skin across the body can detect pressures as small as 0.008g, which is comparable to the sensitivity of a human fingertip. Thus, the weight and instability of even very small accelerometers may cause variation in the way horses move when being tested for lameness. In this study, we used a software package to digitally label videos of individual horses with and without the Lameness Locator applied. Unlike current methods of detection, this software can be used in the natural environment without attaching equipment to the animal. Thus, we hypothesize that the digital video analysis approach will objectively identify shifts in locomotion patterns due to the pressure from the Lameness Locator device. All horses were video recorded at 120fps and a resolution of 1280 × 720p on a standard path while handled in halter at the walk, trot and canter for both the left and right-side views. The DeepLabCut software package was used to extract coordinates for 23 skeletal landmarks as they proceed across the frame. Quantitative gait parameters such as stride length, stance time, and vertical travel of the withers were derived from the landmark tracking data by a robust data processing pipeline. The pipeline comprises a series of operations, including outlier removal due to occlusion, trajectory smoothing, model-fitting-based phase identification, and gait parameters calculation. In this preliminary analysis we considered the stride length, stance time, and the range of travel for the poll, withers and croup at the trot; key metrics traditionally used to assess lameness. Comparing these gait variables within each horse, we found that the right-to-left normalized stride length, stance time, and normalized withers range were all significantly different for each horse between the unencumbered and Lameness Locator equipped trot passes ( P < 0.01, ANOVA JMPv15, SAS Institute). On-going work is expanding this study in a larger sampling of horses, but these preliminary findings suggest that asymmetrically applied equipment does alter gait parameters. We also demonstrate the utility and feasibility of the digital video analysis approach and enable applications in many different scenarios within the horse world.

The Development of Novel 2-in-1 Patient-Specific, 3D-Printed Laminectomy Guides with Integrated Pedicle Screw Drill Guides

To determine if 2-in-1 patient-specific laminectomy and drill guides can be safely used to perform laminectomy and pedicle screw insertion. This was a cadaveric study designed to test novel 2-in-1 patient-specific laminectomy guides, with modular removable pedicle screw drill guides. Three-dimensional (3D) printing has not been applied to laminectomy. This cadaveric study tests novel 2-in-1 patient-specific laminectomy guides, with modular removable pedicle screw drill guides. Computed tomography (CT) scans of 3 lumbar spines were imported into 3D Slicer. Spinal models and patient-specific guides were created and 3D printed. The bones were cleaned to visualize and record the under surface of the lamina during laminectomy. Pedicle screws and laminectomies were performed with the aid of patient-specific guides. CT scans were performed to compare planned and actual screw and laminectomy positions. Thirty screws were inserted in 15 lumbar vertebrae by using the integrated 2-in-1 patient-specific drill guides. There were no cortical breaches on direct examination, or on postoperative CT. Digital video analysis revealed the burr tip did not pass deep to the inner table margin of the lamina in any of the 30 laminectomy cuts. Average surgical time was 4 minutes and 46 seconds (standard deviation, 1 min 38 sec). This study has explored the development of novel 2-in-1 patient-specific, 3D-printed laminectomy guides with integrated pedicle screw drill guides, which are accurate and safe in the laboratory setting. These instruments have the potential to simplify complex surgical steps, and improve accuracy, time, and cost.

Analyzing the Dynamics of a Yo-Yo Using a Smartphone Gyroscope Sensor

In this article, the dynamics of a traditional toy, the yo-yo, are investigated theoretically and experimentally using smartphone sensors. In particular, using the gyroscope the angular velocity is measured. The experimental results are complemented thanks to a digital video analysis. The concordance between theoretical and experimental results is discussed. As the yo-yo is a ubiquitous, simple, and traditional toy, this simple proposal could encourage students to experiment with everyday objects and modern technologies.

Video analysis of one-dimensional multi-body collisions: linear momentum, impulse and energy

Collisions are a key topic in physics and engineering education. An experiment with multiple body one-dimensional collisions is presented, aiming to measure relevant physical quantities by tracking the motion of the system of particles during the collision. Relations between different physical quantities can be explored in the experiment, such as linear momentum, impulse, and energy. Equations are presented for modeling velocity changes during the collisions under the elastic and inelastic conditions and extensions to many body colliders can be easily implemented. Predictions for the velocities and other collision quantities were verified for a set of mass parameters by photogrammetry and digital video analysis.

COMPUTER-AIDED PHASE IDENTIFICATION AND FRAME-TO-FRAME ANALYSIS OF ENDODONTIC ASYMMETRIC RECIPROCATION ROTATION: A PRELIMINARY STUDY

To perform a detailed evaluation of reciprocating motion using a computer-aided phase identification and frame-to-frame analysis, continuous rotation at 300 rpm, RECIPROC ALL mode and WAVEONE ALL-mode were recorded with a high-speed camera. Movie files were automatically analyzed with digital video analysis and modeling tool. RECIPROC ALL mode parameters were 186.34°±1.02 at 428.32 rpm ±7.61 and 65.07°±0.93 at 261.06 rpm ± 7.72; WAVEONE ALL-mode parameters were 191.39°±1.32 at 523.83 rpm ±14.36 and 70.13°±1.26 at 316.06 rpm ± 8.75. The variability of rotational speed during the cycle and distinct acceleration –deceleration patterns, was similar for both reciprocating modes. The computer-aided frame-to-frame analysis revealed that asymmetrical reciprocating motion has more complex kinematics demonstrating high peak rotational speed values and different patterns of acceleration and deceleration. While there was a difference in reciprocating cycle duration and rotational speed, both cycles demonstrated a similar dynamic of rotational speed during the cycle.

Flow Enhancement of Mineral Pastes to Increase Water Recovery in Tailings: A Matlab-Based Imaging Processing Tool

The rate of growth of mining copper industry in Chile requires higher consumption of water, which is a resource limited in quality and quantity and a major point of concern in present times. In addition, the efficient use of water is restricted due to high levels of evaporation (10 to 15 (l/m2) per day), in particular at the north highland mining sites (Chile). On the contrary, the final disposal of tailings is mainly on pond, which loses water by evaporation and in some cases by percolation. An alternative are the paste thickeners, which generate stable paste (70% solids), reducing evaporation and percolation and therefore reducing water make up. Water is a resource with more demand as the industries are expanding, making the water recovery processes more of a necessity than a simple upgrade in efficiency. This technology was developed in Canada (early 80s) and it has widely been used in Australia (arid zones with similar weather conditions to Chile), although few plants are using this technology. The tendency in the near future is to move from open ponds to paste thickeners. One of the examples of this is Minera El Tesoro. This scenario requires developing technical capacity in both paste flow characterization and rheology modifiers (fluidity enhancer) in order to make possible the final disposal of this paste. In this context, a new technique is introduced and experimental results of fluidity modifiers are discussed. This study describes how water content affects the flow behavior and depositional geometry of tailings and silica flour pastes. The depositional angle determined from the flume tests, and the yield stresses is determined from slump test and a rheological model. Both techniques incorporate digital video and image analysis. The results indicate that the new technique can be incorporated in order to determine the proper solid content and modifiers to a given fluidity requirement. In addition, the experimental results showed that the pH controls strongly the fluid paste behavior.

Cisplatin affects locomotor activity and physiological endpoints of Daphnia magna

Cisplatin (CPL) is a common antineoplastic drug used in human medicine for treatment of various cancer types. Since the knowledge about its effects on crustacean behavioral and physiological parameters is very scarce, the aim of our study was to determine the influence of CPL at concentrations of 125 μg/L, 200 μg/L, 500 μg/L and 1000 μg/L on swimming behavior (swimming speed, distance travelled, hopping frequency, propelling efficiency index - a novel parameter) and physiological parameters (heart rate, thoracic limb activity) of Daphnia magna with the use of video digital analysis. The results showed that distance travelled, swimming speed, hopping frequency and propelling efficiency were inhibited as early as after 24 h in concentration- and time-dependent manner. On the other hand, heart rate was stimulated in the animals treated with 125 μg/L of CPL after 48 h, 72 h and 120 h of the exposure, however it was decreased at the higher concentrations. Although thoracic limb activity was considerably increased in daphnids exposed to 125 μg/L and 200 μg/L after 72 h, it was inhibited at the higher concentrations of the drug. The study suggests that since CPL affected daphnid parameters at the environmental concentration, it should be considered as hazardous to zooplankton.

The development of scientific reasoning of preschool children: Micro-analysis of mind–material–body integration

Background: This article argues that the emergence of scientific reasoning in the preschoolyears could be augmented by caregivers and preschool teachers through nurturing ‘Habits ofMind’ (HOM) and ‘Habits of Body’ (HOB) of young children. This type of mind–material–body integration is proposed from an epistemological position that comprises a Hybrid(morphinuum) of theories about early learning and human development.Aim: The aim of this article is to present an exemplar of the capacity of one preschooler toshow emergence and integration of two HOM, namely conjecturing and reasoning withinvariance, in tandem with the Habit of Body (HOB), namely hand-eye coordination that canlay the foundation for scientific reasoning in the early years.Setting: The study referred to in this article is an exemplar (case study) taken from a larger,18-month educational design research intervention, the ‘Little African Scientists Project’. Thatstudy investigated the emergent scientific HOM and HOB through a multimodal materialapproach to pedagogy at preschool level (Grade RR to R).Methods: A three-layered digital video analysis was utilised to interpret the data pertaining toa specific interaction of one child, who was manipulating magnets during one of the manyfree-play activities that formed part of the larger project.Results: Several specific HOM and HOB were evident in the one child who was engaged in anactivity in which he was moving magnets. Two HOM that emerged were those of making andtesting conjectures and reasoning with invariance, while the HOB that emerged was a closealignment of hand movement and eye coordination.Conclusion: This type of close observation and micro-analysis could be utilised for studies ofmore children in similar settings.

New applications of gaze tracking in speech science

We present an overview of speech research applications of gaze tracking technology, where gaze behaviours are exploited as a tool for analysis rather than as a primary object of study. The methods presented are all in their infancy, but can greatly assist the analysis of digital audio and video as well as unlock the relationship between writing and other encodings on the one hand, and natural language, such as speech, on the other. We discuss three directions in this type of gaze tracking application: modelling of text that is read aloud, evaluation and annotation with naïve informants, and evaluation and annotation with expert annotators. In each of these areas, we use gaze tracking information to gauge the behaviour of people when working with speech and conversation, rather than when reading text aloud or partaking in conversations, in order to learn something about how the speech may be analysed from a human perspective.

Validation of the objective assessment of facial movement with a new software-based system

Background: Most used subjective Unilateral Peripheral Facial Palsy (UPFP) grading systems are characterized by high variability and low reproducibility and doesn’t allow a separate evaluation of single facial regions.Objective: To assess the reliability of a new objective method for classification of UPFP, comparing it with House-Brackmann (HB) and Sunnybrook facial grading (SFGS) systems.Method: Forty-seven patients affected by UPFP of different HB grade were included. Each patient underwent a blinded examination by three different operators, via the two subjective methods (HBGS and SFGS) and a newly proposed objective one, that was obtained from a digital video-analysis, named SMART FACIAL system. Results were converted by validated conversion scales into HBGS grades and statistically compared.Results: In 87,23% (n° 41 pts) consistency was found between the grades obtained with all the three evaluation methods; in 10,41% (n°5 pts), between HBGS and SFGS grade and in 2,08% (n°1 pt) between HBGS grades and SMART-FACIAL system. Statistical analysis showed significant correlation among the three systems (p < .000).Conclusions: The SMART FACIAL system presents high reliability also in comparison with the most frequently used subjective methods.Significance: This method represents a fast, simple and thorough way to analyze UPFP, especially during physical rehabilitation.

Sodium Fluorescein–Guided Surgery in Peripheral Nerve Sheath Tumors: First Experience in 10 Cases of Schwannoma

The intravenous application of sodium fluorescein (SF) for brain tumor surgery goes back to the late 1940s. The development of specific fluorophore filters significantly reduced the required dosage of SF and therefore diminished possible side effects. This study investigates the application of SF in benign peripheral nerve sheath tumors (PNSTs), concentrating on its feasibility during microsurgical removal. The single-center study includes 10 consecutive schwannoma cases operated on between September 2016 and March 2017. Inclusion criteria were defined as age ≥18 years, preoperative magnetic resonance imaging with suspicion of schwannoma, and final histopathologic confirmation of schwannoma. Exclusion criteria were a history of intolerance to SF and renal insufficiency. The microsurgical part of each surgery was video recorded, and the collected material was retrospectively analyzed. Red, green, and blue values of various regions of interest set on tumor and normal nerve of each patient were evaluated using ImageJ, an open platform for scientific image analysis. Digital video analysis confirmed the intraoperative impression of increased fluorescence of the tumor in contrast with normal nerve tissue. Because the color yellow is predominantly a mixture of red and green, values of these colors were significantly increased in schwannomas compared with normal nerve tissue (P= 0.0003 and P= 0.0023, respectively). SF reveals increased fluorescence in schwannomas compared with normal nerve tissue. Intraoperative differentiation of tumor and normal nerve tissue becomes possible using a low dose of SF (0.5-1 mg/kg). No side effects occurred. Secure microsurgical preparation is feasible during application of the YELLOW 560 nm filter.