nils-herrmann/clean_scirepeval huggingface dataset:
On the duality of rate allocation and quality indices

In a recent work , the author proposed to study the performance of still image quality indices such as the SSIM by using them as objective function of rate allocation algorithms. The outcome of that work was not only a multi-scale SSIM optimal JPEG 2000 implementation, but also a first-order approximation of the MS-SSIM that is surprisingly similar to more traditional contrast-sensitivity and visual masking based approaches. It will be seen in this work that the only difference between the latter works and the MS-SSIM index is the choice of the exponent of the masking term, and furthermore, that a slight modification of the SSIM definition reproducing the traditional exponent is able to improve the performance of the index at or below the visual threshold. It is hence demonstrated that the duality of quality indices and rate allocation helps to improve both the visual performance of the compression codec and the performance of the index.
On the standardization of the JPEG XT image compression

The ISO recently started a standardization initiative on a forwards-compatible extension of its popular JPEG (ISO/IEC 10918-1) standard. This new standard aims at carefully extending the feature set of the existing technology while preserving the established tool chain built around its 20 years old predecessor. In this work, an overview on JPEG XT, its goals and the underlying technology will be given, and two of the proposed coding technologies for JPEG XT are compared side by side.
A General Model of Mobile Environments: Simulation Support for Strategic Management Decisions

Since the ability of workforce management systems to handle mobility induced challenges of mobile environments like data-communication cut-offs, reduced network bandwidth, and security concerns improved recently, the optimization efforts of mobile enterprises increasingly focus on the organizational setup of their mobile environment. This includes issues like, e.g., the dimension and staffing of regional subdivisions, qualification balance of the workforce, and resource allocation strategies. While this multitude of possible adjustment parameters for optimization prevents from the analytical prediction of organizational change efforts, simulation is a promising approach to analyze mobile environments and their change. In this work we present a formal model representing a generalization of mobile environments. This model can be utilized to examine the cost situation and performance of both real mobile enterprises and projected future development scenarios of such enterprises. The model is developed using colored petri nets (CPN) and the software suite CPN Tools. We show that our model is capable of predicting the outcomes of organizational change projects by the utilization of simulation and present a validation of our model based on real-world data of a German gas and power supply.
VideoEasel — A flexible programmable simulation environment for discrete many body systems

In this work, we present a Virtual Laboratory providing a simulation framework for discrete many-body systems. Programs defining the dynamics of the system and instruments measuring on the simulation can be easily implemented within its own programming language, and can be linked and edited at run time. The system class that can be covered within this framework reaches from discrete difference equations over classical many-body problems is physics to research problems in image processing, allowing us to apply this laboratory in education and research.
Error Bounds for HDR Image Coding with JPEG XT

ISO recently published a new image compression standard, JPEG XT, which extends the popular JPEG standard towards higher dynamic range, compression of alpha channels and lossless coding. In part 7 ofJPEG XT, a two-layer lossy image compression for HDR images isintroduced that reconstructs HDR signals by the combination of a baselayer following the legacy JPEG standard, and an extension layer thatenlarges the dynamic range to that of the original image. While bothbase and extension layer are entropy coded by the mechanisms specifiedin the legacy JPEG standard, only the base layer is visible to legacyJPEG decoders. The original JPEG standard now enforces in its part 2error bounds conforming implementations shall satisfy. The questionanswered in this article is in how far these error bounds carry overto error bounds of JPEG~XT for coding of HDR image signals.
A Comparison of Three Image Fidelity Metrics of Different Computational Principles for JPEG2000 Compressed Abdomen CT Images

This study aimed to evaluate three image fidelity metrics of different computational principles-peak signal-to-noise ratio (PSNR), high-dynamic range visual difference predictor (HDR-VDP), and multiscale structural similarity (MS-SSIM)-in measuring the fidelity of JPEG2000 compressed abdomen computed tomography images from a viewpoint of visually lossless compression. Three hundred images with 0.67- or 5-mm section thickness were compressed to one of five compression ratios ranging from reversible compression to 15:1. The fidelity of each compressed image was measured by five radiologists' visual analyses (distinguishable or indistinguishable from the original) and the three metrics. The Spearman rank correlation coefficients of the PSNR, HDR-VDP, and MS-SSIM values with the number of readers responding as indistinguishable were 0.86, 0.94, and 0.86, respectively. Using the pooled readers' responses as the reference standard, the area under the receiver-operating-characteristic curve for the HDR-VDP (0.99) was significantly greater than that for the PSNR (0.95) (p <; 0.001) and for the MS-SSIM (0.96) (p = 0.003), and there was no significant difference between the PSNR and MS-SSIM (p = 0.70). In measuring the image fidelity, the HDR-VDP outperforms the PSNR and MS-SSIM, and the MS-SSIM and PSNR are comparable.
Reducing randomness of non-regular sampling masks for image reconstruction

Increasing spatial image resolution is an often required, yet challenging task in image acquisition. Recently, it has been shown that it is possible to obtain a high resolution image by covering a low resolution sensor with a non-regular sampling mask. Due to the masking, however, some pixel information in the resulting high resolution image is not available and has to be reconstructed by an efficient image reconstruction algorithm in order to get a fully reconstructed high resolution image. In this paper, the influence of different sampling masks with a reduced randomness of the non-regularity on the image reconstruction process is evaluated. Simulation results show that it is sufficient to use sampling masks that are non-regular only on a smaller scale. These sampling masks lead to a visually noticeable gain in PSNR compared to arbitrary chosen sampling masks which are non-regular over the whole image sensor size. At the same time, they simplify the manufacturing process and allow for efficient storage.
Spatially distributed aggregation of a polarization-division multiplexed superchannel by frequency conversion in fiber

We extend our concept for distributed ultra-dense frequency-division multiplex of single-polarization subcarriers to multiplex of polarization-division multiplexed (PDM) subcarriers. Precise frequency allocation of PDM subcarriers within a 400-Gb/s superchannel is experimentally validated with Nyquist-shaped PDM-QPSK subcarriers.
A Standardized Metadata Set for Annotation of Virtual and Remote Laboratories

Online Laboratories and Virtual Experiments start to play an increasingly important role in the education of Engineering and Science Education. While several repositories for online and virtual experiments are available, a common method for annotating experiments to simplify their discovery is not yet available and accepted. In 2010, an international group of online lab providers formed the Global Online Lab Consortium (GOLC) to address the issues of interoperability between online laboratories and laboratory compilations, one of its activities is the establishment of an ontology and a common metadata set that addresses not only the needs of typical lab providers and lab users, but also of storage and archival institutions such as libraries. This article describes the current status of the GOLC activities in the metadata subcommittee, lists the requirements of various user groups of the metadata set and provides insight into both the underlying ontology and the metadata specifications themselves.
Sequential polarization imaging using multi-view fusion

Multi-channel imaging like RGB is common today, however, a custom configuration of other modalities, such as wavelengths or polarization, is expensive and often unavailable. We propose a novel configurable multi-modal imaging system that solves this problem by using off-the-shelf components and proper fusion algorithms. The paper shows the application of polarization imaging for machine vision inspection. Sequential images acquired with different cameras and polarization angles are first registered and then fused together. With standard components, we demonstrate a superior image quality to existing specialized cameras while being significantly cheaper, available, and easily configurable.
Visual quality improvement techniques of HDPhoto/JPEG-XR

Microsoft's recently proposed new image compression codec HDPhoto is currently undergoing ISO standardization as JPEG-XR. Even though performance measurements carried out by the JPEG committee indicated that the PSNR performance of HDPhoto is competitive, the visual performance of HDPhoto showed notable deficits, both in subjective and objective tests. This paper introduces various techniques that improve the visual performance of HDPhoto without leaving the current codestream definition. Objective measurements performed by the author indicate that the modified encoder, while staying backwards compatible to the current standard proposition, improves visual performance significantly, and the performance of the modified encoder is similar to JPEG.
Towards electronic exams in undergraduate engineering

In this work, we describe the first step towards electronic exams at the University of Stuttgart. The motivation, both driven by students and lecturers, is to offer assessments that are closer to real-life programming by allowing interactive programming and debugging not possible with pen and paper exams. This is in so far important as skills in computer algebra systems as for example MATLAB or programming languages like Java are an elementary ingredient of any engineering study nowadays. In this paper, we describe the technological basis tor computer based exams based on a system already successfully deployed for homework assignments, and describe its transition to an electronic assessment system. We discuss not only the technological requirements on software, its architecture and our choices for hardware, but also provide a brief introduction into the organizational and legal challenges that we are going to overcome.
Precise remote optical carrier addition into 200-Gb/s CO-OFDM channel using fiber frequency conversion

We propose a locally defined precise subcarrier addition into an orthogonal frequency-division multiplexed signal using fiber-frequency conversion. A 12.5-GBd QPSK-signal is added into an exact frequency grid to generate 200-Gb/s CO-OFDM at a free-running remote node without additional OSNR penalty.
Reconstruction of videos taken by a non-regular sampling sensor

Recently, it has been shown that a high resolution image can be obtained without the usage of a high resolution sensor. The main idea has been that a low resolution sensor is covered with a non-regular sampling mask followed by a reconstruction of the incomplete high resolution image captured this way. In this paper, a multi-frame reconstruction approach is proposed where a video is taken by a non-regular sampling sensor and fully reconstructed afterwards. By utilizing the temporal correlation between neighboring frames, the reconstruction quality can be further enhanced. Compared to a state-of-the-art single-frame reconstruction approach, this leads to a visually noticeable gain in PSNR of up to 1.19 dB on average.
Fine-tuning JPEG-XT compression performance using large-scale objective quality testing

The upcoming JPEG XT standard for High Dynamic Range (HDR) images defines a common framework for the lossy and lossless representation of high-dynamic range images. It describes the decoding process as the combination of various processing tools that can be combined freely. In this paper we analyze the coding efficiency of different decoding tools through a large scale objective quality testing using the HDR-VDP 2.2 objective metric. This evaluation is performed on a large database of 337 images, testing the effect of global and local tone mapping operators for various configurations, and for multiple combinations of quality parameters. The main findings are that using an inverse tone mapping operator for creating an HDR precursor image works well for global, but not for local operators, and that including refinement scans to increase the bit-depth of the extension layer provides substantial improvements for one of the encoding profiles and higher bit-rates.
Robust super-resolution in a multiview setup based on refined high-frequency synthesis

Increasing image sharpness and thus improving the visual quality is an important task in multiview image and video processing. We propose a novel super-resolution approach for multiview images in a mixed-resolution setup that is robust to various depth map distortions. The considered distortion scenarios may be caused by an inaccurate calibration of the depth camera or a limitation of depth range. Our method is based on a refined high-frequency synthesis that relies on a blockwise and depth-dependant low-frequency registration. The refinement step efficiently adapts the high-frequency content from a neighboring high-resolution camera to a low-resolution view and thereby compensates the displacement caused by depth inaccuracies. In case of undistorted depth maps, the results show that our algorithm leads to a PSNR gain of up to 1.33 dB with respect to a comparable unrefined super-resolution approach for a mixed-resolution multiview video plus depth format. Compared to the initial low-resolution view, a PSNR gain of up to 2.61 dB is obtained. In case of distorted depth maps, a PSNR gain of even 4.78 dB is achieved with respect to the reference superresolution algorithm. The PSNR gains get confirmed by the corresponding SSIM values which manifest a similar behaviour. The improvement of visual quality is also convincingly for all considered scenarios.
Efficient lossless coding of highpass bands from block-based motion compensated wavelet lifting using JPEG 2000

Lossless image coding is a crucial task especially in the medical area, e.g., for volumes from Computed Tomography or Magnetic Resonance Tomography. Besides lossless coding, compensated wavelet lifting offers a scalable representation of such huge volumes. While compensation methods increase the details in the lowpass band, they also vary the characteristics of the wavelet coefficients, so an adaption of the coefficient coder should be considered. We propose a simple invertible extension for JPEG 2000 that can reduce the filesize for lossless coding of the highpass band by 0.8% on average with peak rate saving of 1.1%.
Phase-Incoherent DQPSK Wavelength Conversion Using a Photonic Integrated Circuit

We investigate the performance of a large-scale, silica-on-silicon photonic integrated circuit for multiformat signal processing, and we experimentally demonstrate wavelength-conversion of (differential) quadrature phase-shift keying [(D)QPSK] signals. The circuit exploits phase-incoherent techniques to decode the input signal and to phase remodulate two phase-shift-keying components before combining them in a common QPSK output stream. Error-free wavelength conversion with 4-dB power penalty is reported at 44 Gb/s.
Super-resolution for differently exposed mixed-resolution multi-view images adapted by a histogram matching method

Super-resolution is an important task in the image and video processing domain. In mixed-resolution multi-view scenarios, neighboring high-resolution reference perspectives can be used to increase the image quality of a given low-resolution target view. By using corresponding depth information, the required high-frequency part can be projected from a reference view onto the image plane of the target perspective. However, the contrast and thus the amount of high-frequency information in a reference view varies with the cameras exposure settings. As a consequence, the resulting super-resolution quality drops in case of exposure time variations between the different views. By incorporating a histogram matching method, the required high-frequency part can be efficiently adapted to the exposure settings of the target view. The simulation results show that the proposed adaption leads to an average PSNR gain of 0.63 dB for differently exposed mixed-resolution multi-view setups.
SSIM as global quality metric: A differential geometry view

While traditional image quality metrics like MSE are mathematically well understood and tractable, they are known to correlate weakly to image distortion as observed by human observers. To address this situation, many full reference quality indices have been suggested over the years that correlate better to human perception, one of them being the well-known Structural Similarity Index by Wang and Bovik. However, while these expressions show higher correlations, they are often not very tractable mathematically, and — in specific — are rarely metrics in the strict mathematical sense. Specifically, the triangle inequality is often not satisfied, which could either be seen as an effect of the human visual system being unable to compare images that are visually too different, or as a defect of the index capturing the global situation correctly. In this article, the latter position is taken, and it is shown how the SSIM can be understood as a local approximation of a global metric, namely the geodesic distance on a manifold. While the metric cannot be computed explicitly in most cases, it is nevertheless shown that in specific cases its expression is identical to Weber's Law of luminance sensitivity of the human eye.
Evaluation of floating point image compression

Recently, compression of High Dynamic Range (HDR) photography gained attention in the standardization of the Microsoft HDPhoto compression scheme as JPEG-XR. While integer data of 16 bits/pixel (bpp) in scRGB color-space can represent images up to a dynamic range of about 3.5 magnitudes in luminance - a noteworthy improvement over the 1.6 magnitudes possible in sRGB - even higher ranges are more efficiently represented by floating-point number formats. However, traditional means to evaluate image quality are rarely suitable for such data: They are often only calibrated to lowdynamic ranges (LDR) of 8bpp, and are not designed to take the peculiarities of floating-point data into account. In this work, we present two approaches to deal with this problem by introducing a (mathematical) quality index more suitable to floating point data related to SSIM , , and by presenting an independent image quality evaluation framework that is able to apply LDR metrics to HDR data. The presented ideas are then tested on the HDPhoto floating point compression, on a proprietary backwards compatible extension of JPEG [10] and on a proposed floating point compression scheme based on JPEG 2000  that is also proven to be optimal in the proposed quality index. It is then shown that both approaches, the proposed metric and PSNR in the LDR domain, deliver comparable results.
Robotics as demonstrator discipline for networked virtual and remote laboratories

Based on the BW-eLabs platform, the goal of the NETLABS is the development of a ubiquitous software portal, allowing researchers to move backward and forward between interlinked experimental superstructures and simulations in a 3D knowledge space. Robotics - as one of the most important key technologies of the 21st century - is in a special need of “virtual infrastructure support” because of its cost-intenseness. The environments where these systems can be examined in both a simulative as well as a realistic manner are manifold. Due to the accessibility of the different robotics applications, new trials can be tested faster and at a reasonable price. In NetLabs, a role- and rights-based model is developed, allowing access to experiments or measured data. The necessary components are integrated in the 3D Wonderland engine.
A Mathematical Model for the Characterization of Superconducting Level Sensors

An automated level control in cryogenic systems requires a precise and continuous level measurement. If properly characterized, superconducting level sensors are a viable option for the same. The operation of a superconducting level sensor is based on the difference in the heat transfer from the sensor wire to the liquid and the gaseous phases of the cryogen. The higher heat transfer in the liquid phase results in a superconductive status, whereas the lower heat transfer in the gaseous phase results in a normal conductive status with a voltage drop corresponding to the length of the wire in the gaseous phase. Hence, it demands a judicious selection of the sensor and the operational parameters such as the current input, for an accurate level measurement as well as the reduction of the liquid boil off. In this paper, to simulate the operation of a superconducting level sensor, a model has been developed by taking the steady-state heat balance along the sensor wire. It is then used for the investigation of the sensor current, voltage output at various liquid levels, and temperature profile of the sensor wires of NbTi and MgB2 /SS level sensors in LHe. Furthermore, design guidelines have been proposed for an MgB2/SS superconducting level sensor for LH2 level measurement. The parameters considered for the analysis are the sensor wire diameter and the active length. In addition, the effect of an external resistor on the sensor operation is also studied.
Distributed Ultradense Optical Frequency-Division Multiplexing Using Fiber Nonlinearity

We extend our investigations on a recently proposed concept for distributed coherent optical orthogonal frequency- division multiplexing (CO-OFDM) by fiber-frequency conversion for locally defined exact channel mapping based on free-running lasers. Experiments with quadrature phase-shift keying and 16-quadrature amplitude modulation subchannels show error-free performance and are compared to experiments with locally generated CO-OFDM.
Multi-generation-robust Coding with JPEG XS

The JPEG committee (formally, ISO SC29 WG1) is currently standardizing a lightweight mezzanine codec for video over IP transport under the name JPEG XS. A particular challenging design constraint of this codec is multi-generation robustness, that is the necessity to minimize the error built-up under multiple re-compression cycles. In this paper, we discuss the sources of such errors, how they are avoided in the JPEG XS design and compare the multi-generation robustness of JPEG XS with that of other codecs.