Camera Operation Research Articles

Integration and calibration of a multi slit spectropolarimeter

Multi-slit spectropolarimeter is a next-generation spectropolarimeter to obtain vector magnetic field information at high spatial, spectral, and temporal resolution for studying the magnetic structures on the Sun. Once developed, it can be used as ground based instrument at solar observatories, also as a space payload for various solar missions. A high spectral resolution is invariably an important parameter for accurate vector magnetic field measurements and faster cadence is required for the study of dynamical evolution of structures (e.g., solar flares, sunspots etc.) on the Sun and hence better understanding on the physics behind their evolution.The multi-slit spectropolarimeter mainly consists of a spectrograph, polarimeter package and an area-array detector (CCD camera). The spectrograph consists of multi-slit (5-slits), diffraction grating, collimator and camera lens system. Integration of the polarimeter and detector is achieved by using a LabVIEW GUI platform. User controllable options for camera and LCVR settings were developed in LabVIEW. The CCD camera operation for capturing images is synchronized with the clock used to switch the voltage supplied to the LCVR. This is achieved by providing an external trigger signal from LCVR to camera. Acquisition of data is carried out through CCD into a widely used FITS format along with the experimental settings and other required information. This is achieved using the LabVIEW GUI developed. A calibration curve for voltage versus retardance for LCVR was obtained using an experimental setup. Multi-slit spectrograph was calibrated by filling all the slits using a laser source. Preliminary study of the instrument’s polarization response was carried for linearly polarized input.

The System of Visual Assessment of Technical State of Underwater Objects

This material presents the results of works implemented so far at the Department of Underwater Work Technology of the Polish Naval Academy in Gdynia, Poland, within the project No. O N502 274039, focused on an attempt to prepare theoretical assumptions for the visual diagnostics system for underwater objects. The main accomplishments until now have been the preparation of a mathematical model allowing specification of dimensions of photographed underwater objects and construction of a prototype underwater photogrammetric camera. The said device is used for collecting data required in the mathematical model. Moreover, the project involved carrying out experiments which provided the basis for determining optical parameters of the constructed camera. In prospect, the works on the application for the operation of the photogrammetric camera will be accompanied by construction works on a visual assessment system allowing for quantitative and qualitative verification of the state of examined underwater objects.

Cinematic innervation: the intuitive form of perception in the distracted perceptual field

In “The Work of Art in the Age of Its Technological Reproducibility,” Walter Benjamin alluded that the human perceptual field in his time would become more distracted by the intervention of technologies, and so masses’ tactility activated by distraction would be more important in the mechanized perception. Regarding this historical situation, Benjamin anticipated that the new mode of mass perception would be organized through people's collective “innervation” to technologies. This article aims to contextualize this physiological term's cultural, technical, and political implications within various discourses about perception from the late 19th century physiologies to early 20th century film theories. Benjamin considers the tactility of people's potential to reconstruct the optical scheme of perception from the “flatness of screen” in which distances between viewers and perceived objects collapse. In a similar vein, the late 19th century's physiology reconceptualized perception in its relation not so much to the transcendental division of subject/object as to the sensual condition of a retina as “a single immanent plane.” From this perspective, perception is phenomena entailed by a body's contact to a sensual environment, so how sense inputs circulate in a neural network is a determinant for explaining perceptual processes. With regard to this paradigm change, the invention of cinema in the late 19th century was significant because it radically changed the composition of the perceptual field in two directions. Cinema introduced the virtualized perceptual fields on which sense circulations were completely controlled by the operation of camera. At the same time, the mediation of projectors in theaters reorganized viewers’ neural paths for perceptual innervation. As Hugo Münsterberg and Sergei Eisenstein's theories reflect, cinematic media's intervention in the perceptual field made it possible for masses’ collective consciousness to be redrawn as a social nervous system on a neurophysiological level, so this media functioned as a social apparatus for the mechanization/modernization of humanity.

A study on carrier phase distortion in phase measuring deflectometry with non-telecentric imaging

In phase measuring deflectometry (PMD), the fringe pattern deformed according to slope deviation of a specular surface is digitized employing a phase-shift technique. Without height-angle ambiguity, carrier-removal process is adopted to evaluate the variation of surface slope from phase distribution when a quasi-plane is measured. However, the difficulty lies in the fact that the nonlinearity is generally contained in the carrier frequency due to the restrictions of system geometries. This paper investigates nonlinear carrier components introduced by the generalized imaging process in PMD. Furthermore, the analytical expression of carrier components in PMD is presented for the first time. The presented analytical form of carrier components can be extended to analyze and describe various effects of system parameters on carrier distortion. Assuming a pinhole perspective model, carrier phase distribution of arbitrary geometric arrangement is modeled as a function of spatial variables by exploring ray tracing method. As shown by simulation and experimental results, the carrier distortion is greatly affected by non-telecentric camera operation. Experimental results on the basis of reference subtraction technique further demonstrate that restrictions on reflection system geometry can be eliminated when the carrier phase is removed elaborately.

Fourier domain optical coherence tomography system with balance detection

A Fourier domain optical coherence tomography system with two spectrometers in balance detection is assembled using each an InGaAs linear camera. Conditions and adjustments of spectrometer parameters are presented to ensure anti-phase channeled spectrum modulation across the two cameras for a majority of wavelengths within the optical source spectrum. By blocking the signal to one of the spectrometers, the setup was used to compare the conditions of operation of a single camera with that of a balanced configuration. Using multiple layer samples, balanced detection technique is compared with techniques applied to conventional single camera setups, based on sequential deduction of averaged spectra collected with different on/off settings for the sample or reference beams. In terms of reducing the autocorrelation terms and fixed pattern noise, it is concluded that balance detection performs better than single camera techniques, is more tolerant to movement, exhibits longer term stability and can operate dynamically in real time. The cameras used exhibit larger saturation power than the power threshold where excess photon noise exceeds shot noise. Therefore, conditions to adjust the two cameras to reduce the noise when used in a balanced configuration are presented. It is shown that balance detection can reduce the noise in real time operation, in comparison with single camera configurations. However, simple deduction of an average spectrum in single camera configurations delivers less noise than the balance detection.

Emocap

Authoring quality video content is difficult since proper camerawork is required for delivering content which appropriately reflects user’s expressive intentions. Based on an experimental result on non-expert users, the incremental interaction model was formerly proposed. The authors propose a system based on the model which compensates for user’s lack of cinematographic knowledge or skills by relating affective information such as atmosphere or mood to shooting techniques. After selecting a specific type of atmosphere to express non-verbal information, the system analyzes the shooting image and the camera operation including the camera angle and the zooming speed to assist the user. The appropriate parameters for shot sizes, camera angles and zoom speed are based on the analysis of extracted features from ten highly-evaluated films. The system evaluation has indicated that the system assists the user in reflecting user intention of the shot appropriately; therefore it enables the user to capture shots more appropriately and effectively without cinematographic knowledge or skills.

Numerical Analysis of Sampling Streak Camera for Higher Temporal Resolution Operation

The streak camera is one of the highest temporal resolution measurement devices for luminous phenomena, and the sampling streak camera is its advanced device for image measurements in time domain. In general, the temporal resolution of the sampling streak camera is less than that of the conventional streak camera due to complicated electron motion in the device. For improvement of the sampling streak camera for higher temporal resolution of order of pico-second, understanding of physical phenomena in this device is essential and then numerical analysis play an important role. This paper presents a numerical analysis method of the sampling streak camera based on self-consistent simulation of electrostatic field and relativistic electron beam motion by using particle-in-cell (PIC) method. It is predicted from the numerical simulation that higher temporal resolution operation of the sampling streak camera will cause serious inaccuracy in phase information due to the space charge effects.

Single-Port Thymectomy Through an Infrasternal Approach

We report a surgical procedure in which a port and devices designed for single-incision endoscopic surgery are employed for thymectomy through an infrasternal approach. As this single-port thymectomy procedure can be performed through a single 3.5-cm incision in the abdominal region usually concealed under clothes, it is esthetically excellent and is among the least invasive thymectomy procedures because no sternal incision is applied and no intercostal nerve is injured. Investigation of the safety of this procedure and long-term therapeutic outcomes for myasthenia gravis and anterior mediastinal tumors is necessary.

Temperature Dependent Operation of PSAPD-Based Compact Gamma Camera for SPECT Imaging

We investigated the dependence of image quality on the temperature of a position sensitive avalanche photodiode (PSAPD)-based small animal single photon emission computed tomography (SPECT) gamma camera with a CsI:Tl scintillator. Currently, nitrogen gas cooling is preferred to operate PSAPDs in order to minimize the dark current shot noise. Being able to operate a PSAPD at a relatively high temperature (e.g., 5 °C) would allow a more compact and simple cooling system for the PSAPD. In our investigation, the temperature of the PSAPD was controlled by varying the flow of cold nitrogen gas through the PSAPD module and varied from -40 °C to 20 °C. Three experiments were performed to demonstrate the performance variation over this temperature range. The point spread function (PSF) of the gamma camera was measured at various temperatures, showing variation of full-width-half-maximum (FWHM) of the PSF. In addition, a 99mTc-pertechnetate (140 keV) flood source was imaged and the visibility of the scintillator segmentation (16×16 array, 8 mm × 8 mm area, 400 μm pixel size) at different temperatures was evaluated. Comparison of image quality was made at -25 °C and 5 °C using a mouse heart phantom filled with an aqueous solution of 99mTc-pertechnetate and imaged using a 0.5 mm pinhole collimator made of tungsten. The reconstructed image quality of the mouse heart phantom at 5 °C degraded in comparision to the reconstructed image quality at -25 °C. However, the defect and structure of the mouse heart phantom were clearly observed, showing the feasibility of operating PSAPDs for SPECT imaging at 5 °C, a temperature that would not need the nitrogen cooling. All PSAPD evaluations were conducted with an applied bias voltage that allowed the highest gain at a given temperature.

Towards Unrestrained Depth Inference with Coherent Occlusion Filling

Traditional depth estimation methods typically exploit the effect of either the variations in internal parameters such as aperture and focus (as in depth from defocus), or variations in extrinsic parameters such as position and orientation of the camera (as in stereo). When operating off-the-shelf (OTS) cameras in a general setting, these parameters influence the depth of field (DOF) and field of view (FOV). While DOF mandates one to deal with defocus blur, a larger FOV necessitates camera motion during image acquisition. As a result, for unfettered operation of an OTS camera, it becomes inevitable to account for pixel motion as well as optical defocus blur in the captured images. We propose a depth estimation framework using calibrated images captured under general camera motion and lens parameter variations. Our formulation seeks to generalize the constrained areas of stereo and shape from defocus (SFD)/focus (SFF) by handling, in tandem, various effects such as focus variation, zoom, parallax and stereo occlusions, all under one roof. One of the associated challenges in such an unrestrained scenario is the problem of removing user-defined foreground occluders in the reference depth map and image (termed inpainting of depth and image). Inpainting is achieved by exploiting the cue from motion parallax to discover (in other images) the correspondence/color information missing in the reference image. Moreover, considering the fact that the observations could be differently blurred, it is important to ensure that the degree of defocus in the missing regions (in the reference image) is coherent with the local neighbours (defocus inpainting).

SU-E-T-71: Modified Machine Uptime Calculation for a Modern LINAC

Purpose: to calculate uptime for a modern linear accelerator(LINAC). Method and Materials Current Method: LINAC uptime is not only a major factor that influences the cost of running the facility but also influences associated service contracts. LINAC uptime according to LINAC manufacturer e.g. Elekta is: Uptime = (BaseTime — Down Time)/BaseTime This is an age old formula. Maturity of latest LINACs and redundancy of available components significantly reduced downtime. Interesting point to consider is the actual improvements in quality and speed of treatment caused by many new add‐on features. Proposed Method: Delays that are generally not considered as machine downtime but influence the treatment time and costs are: • Improperly tuned dose rate causing control system resets • Artifacts in KV or MV images • Patient Positioning System movements • MLC movements that cause system resets during treatment. Corrections are proposed to the above formula as follows: Uptime = (BaseTime — DownTime — OverAllDelayTime)/BaseTime Where OverallDelaytime = Sigma Di . ‘Di’ is delay due to ith “inconvenience”, such as the one listed above. Cost of such inconveniences in one year: Yearly Operating Loss = Sigma DiL ‘L’ is the cost per minute of therapists operating the accelerator. Other issues not controlled by LINAC vendors and to be factored into the service contracts of appropriate entities: • Chillers that maintain tap water temperature • Humidity levels in the facility • Distilled water levels • Treatment room door and camera operations • Linac sequencer problems, e.g. • communication errors • software issues • hardware issues Results: The proposed method accurately represents LINAC Uptime. Conclusions: Uptime is significantly less than current calculations.

Early Multi-institution Experience With Single-Incision Laparoscopic Colectomy

Single-incision laparoscopic colectomy represents a potential advance in minimally invasive surgical approaches to colorectal disease. Although widely promoted, outcome data are virtually absent. A group of highly experienced laparoscopic attending colorectal surgeons convened to standardize technique and prospectively record operative details and outcomes. Single-incision laparoscopic colectomy was performed by 10 experienced attending colorectal surgeons with minimal or no prior single-incision laparoscopic colectomy experience. Surgeon rating of ergonomics and 15 components of operation conduct was compared with conventional multiple-port laparoscopic colectomy. Patient demographics, operative details, and outcome data were prospectively collected. Thirty-nine single-incision laparoscopic colectomies were performed (25 right colectomies, 5 ileocolic resections, 8 sigmoidectomies, and 1 low anterior resection). Underlying pathology included polyps (12), cancer (15), Crohn's disease (5), and diverticulitis (7). Patients were highly selected with a mean body mass index of 25.6 (range, 16-40). Two conversions to open resection occurred, 1 because of fistula and 1 because of adhesions, in patients with a mean body mass index of 34. An additional port was required in 3 patients. Mean incision length was 4.2 cm (range, 2.5-8) and operative time was 120 minutes (range, 68-210). Complications included 1 wound infection and 2 anastomotic bleeds requiring transfusion. Average length of stay was 4.4 days (range, 2-8). Mean lymph node harvest was 19 (range, 12-39). Exposure, instrument conflict, ergonomics, ease of instrumentation, and camera operation were rated significantly more difficult with single-incision laparoscopic colectomy than with multiple-port laparoscopic colectomy. Preliminary data demonstrate that single-incision laparoscopic colectomy can be performed safely in selected patients by experienced surgeons. The benefits of single-incision compared with multiple-port laparoscopic colectomy are not immediately evident. Despite the advanced skills of the faculty, a learning curve of undetermined length still exists in which specific components of single-incision laparoscopic colectomy are more difficult than multiple-port laparoscopic colectomy, and areas of focus remain that require advances to make single-incision laparoscopic colectomy equivalent to multiple-port laparoscopic colectomy. The multi-institutional registry will enable further analysis of single-incision laparoscopic colectomy.

Robust Spatiotemporal Matching of Electronic Slides to Presentation Videos

We describe a robust and efficient method for automatically matching and time-aligning electronic slides to videos of corresponding presentations. Matching electronic slides to videos provides new methods for indexing, searching, and browsing videos in distance-learning applications. However, robust automatic matching is challenging due to varied frame composition, slide distortion, camera movement, low-quality video capture, and arbitrary slides sequence. Our fully automatic approach combines image-based matching of slide to video frames with a temporal model for slide changes and camera events. To address these challenges, we begin by extracting scale-invariant feature-transformation (SIFT) keypoints from both slides and video frames, and matching them subject to a consistent projective transformation (homography) by using random sample consensus (RANSAC). We use the initial set of matches to construct a background model and a binary classifier for separating video frames showing slides from those without. We then introduce a new matching scheme for exploiting less distinctive SIFT keypoints that enables us to tackle more difficult images. Finally, we improve upon the matching based on visual information by using estimated matching probabilities as part of a hidden Markov model (HMM) that integrates temporal information and detected camera operations. Detailed quantitative experiments characterize each part of our approach and demonstrate an average accuracy of over 95% in 13 presentation videos.

The Use of Security Cameras with Privacy Protecting Ability

A novel method of security camera operation is proposed. In the method, security cameras, which encrypt the taken images and store them into the memory card inside, are used. Only when crimes occur, the memory cards are taken out from the cameras and the images are decrypted with the key and viewed by the city government and/or the police. When no crimes occur, images are overwritten by the new ones after a week automatically without being viewed by anyone. By using the stand-alone cameras without wiring to the control center, the installation cost and the operation cost are much lower than CCTV cameras. By using image encryption, the privacy of the tourists is protected. Using this system, high density installation of the security cameras with very low cost can be realized in encryption with image encryption privacy protection function.

The Visible Intensified Cameras for Plasma Imaging in the TJ‐II Stellarator

AbstractVisible cameras are widely used in fusion experiments for diagnosis and for machine safety issues. They are generally used to monitor the plasma emission, but are also sensible to surface Blackbody radiation and Bremsstrahlung. Fast or high speed cameras capable of operating in the 105 frames per second speed range are today commercially available and offer the opportunity to plasma fusion researchers of two‐dimensional (2D) imaging of fast phenomena such as turbulence, ELMs, disruptions, dust, etc. The tracking of these fast phenomena requires short exposure times down to the μ s range and the light intensity can be often near the signal to noise ratio limit especially in low plasma emission regions such as the far SOL Additionally, when using interference filters to monitor, e.g. impurity line emission, the photon flux is strongly reduced and the emission cannot be imaged at high speed. Therefore, the use of image intensifiers that amplify the light intensity onto the camera sensor can be of great help. The present work describes the use of intensifiers in the visible fast cameras of TJ‐II stellarator. We have achieved spectroscopic plasma imaging of filtered impurity atomic line emission at short exposure times down to the 10 μ s range depending on atomic line and concentration. Additionally, plasma movies at velocities of 2x105 frames per second near the camera operation limit can be recorded with exposure times well below 1 μ s with sufficient signal to noise ratio. Although an increasing degradation of the image quality appears when raising the light amplification, an effective gain of up to two orders of magnitude of the light intensity is feasible for many applications (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Lunar occultations of sources in the near-infrared towards the Galactic Centre

The rare passages of the moon’s disc in the high stellar density region in the vicinity of the Galactic Centre provides an opportunity of using lunar occultation (LO) technique in the near-infrared (near-IR) region to study occulted sources at high angular resolutions of a few milliarcseconds. During one such passage we have observed a dozen events successfully in the K band using the fast subarray mode of operation of the NICMOS IR camera attached to the 1.2-m telescope at Mt Abu, India. The minimum approach to Galactic Centre during the observations was 1. ◦ 0. A detailed analysis of the occultation light curves and limiting angular resolution of this method shows that majority of the sources are unresolved (φUD < 3 mas). In three cases the sources are found to have angular sizes larger than the resolution limits of the technique used.

Sustainable Tourism Using Security Cameras with Privacy Protecting Ability

For sustainable tourism, a novel method of security camera operation is proposed. In the method, security cameras, which encrypt the taken images and store them into the memory card inside, are used. Only when crimes occur, the memory cards are taken out from the cameras and the images are decrypted with the key and viewed by the city government and/or the police. When no crimes occur, images are overwritten by the new ones after a week automatically without being viewed by anyone. By using the stand-alone cameras without wiring to the control center, the installation cost and the operation cost are much lower than CCTV cameras. By using image encryption, the privacy of the tourists is protected. Using this system, high density installation of the security cameras with very low cost can be realized in encryption with image encryption privacy protection function

Demosaicing algorithms for area- and line-scan cameras in print inspection

Most color image sensors use color filter arrays (CFA). With this sensor design the captured information at each sensor pixel position is restricted to a specific spectral portion (typically red, green and blue bands). To obtain the missing color responses at each pixel position, so-called CFA demosaicing algorithms are commonly used. We propose two new CFA demosaicing algorithms, which are well suited for industrial print inspection with respect to the requirements in accuracy and speed. As a main contribution, we introduce novel demosaicing algorithms for specific high-speed color digital time delay and integration (DTDI) CFA line-scan cameras. We compare the suggested CFA demosaicing algorithms to state-of-the art algorithms for area and line-scan camera operation modes. We show that the two new algorithms perform superior to conventional algorithms as indicated by reconstruction error.

Two-dimensional entropy model for video shot partitioning

A shot presents a contiguous action recorded by an uninterrupted camera operation and frames within a shot keep spatio-temporal coherence. Segmenting a serial video stream file into meaningful shots is the first pass for the task of video analysis, content-based video understanding. In this paper, a novel scheme based on improved two-dimensional entropy is proposed to complete the partition of video shots. Firstly, shot transition candidates are detected using a two-pass algorithm: a coarse searching pass and a fine searching pass. Secondly, with the character of two-dimensional entropy of the image, correctly detected transition candidates are further classified into different transition types whereas those falsely detected shot breaks are distinguished and removed. Finally, the boundary of gradual transition can be precisely located by merging the characters of two-dimensional entropy of the image into the gradual transition. A large number of video sequences are used to test our system performance and promising results are obtained.

An Accurate Scene Segmentation Method Based on Graph Analysis Using Object Matching and Audio Feature

A method for accurate scene segmentation using two kinds of directed graph obtained by object matching and audio features is proposed. Generally, in audiovisual materials, such as broadcast programs and movies, there are repeated appearances of similar shots that include frames of the same background, object or place, and such shots are included in a single scene. Many scene segmentation methods based on this idea have been proposed; however, since they use color information as visual features, they cannot provide accurate scene segmentation results if the color features change in different shots for which frames include the same object due to camera operations such as zooming and panning. In order to solve this problem, scene segmentation by the proposed method is realized by using two novel approaches. In the first approach, object matching is performed between two frames that are each included in different shots. By using these matching results, repeated appearances of shots for which frames include the same object can be successfully found and represented as a directed graph. The proposed method also generates another directed graph that represents the repeated appearances of shots with similar audio features in the second approach. By combined use of these two directed graphs, degradation of scene segmentation accuracy, which results from using only one kind of graph, can be avoided in the proposed method and thereby accurate scene segmentation can be realized. Experimental results performed by applying the proposed method to actual broadcast programs are shown to verify the effectiveness of the proposed method.