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Water can exhibit many different colors due to a variety of physical properties. Here, we focus on some observable colors within very pure freshwater. We only treat the absorption of light due to electronic and ro-vibrational excitations and scattering due to refractive index fluctuations of the water and the respective consequences for the appearance of colors.
Freezing of lakes is described using a simplified one-dimensional model, which gives ice thickness, ice growth rates, and ice surface temperature as a function of time. Model data for a specific lake with known meteorological conditions are compared to estimated ice thickness using a simple optical method. Finally, more advanced potential students projects are briefly discussed and results of a numerical solution are compared to the simplified model.
Since the face morphing attack was introduced by Ferrara et al. in 2014, the detection of face morphings has become a wide spread topic in image forensics. By now, the community is very active and has reported diverse detection approaches. So far, the evaluations are mostly performed on images without post-processing. Face images stored within electronic machine readable documents (eMRTD) are ICAO-passport-scaled to a resolution of 413x531 and a JPG or JP2 lesize of 15 kilobytes. This paper introduces a face morphing detection concept with 3 modules (ICAO-aligned pre- processing module, feature extraction module and classi cation module), tailored for such images on eMRTD. In this work we exemplary design and evaluate two feature spaces for the feature extraction module, a frequency domain and a spatial domain feature space. Our evaluation will compare both feature spaces and is carried out with 66,229 passport-scaled images (64,363 morphed face images and 1,866 authentic face images) which are completly independent from training and include all images provided for the IHMMSEC'19 special session: "Media Forensics - Fake or Real?". Furthermore, we investigate the in uence of di erent morph gen- eration pipelines to the detection accuracies of the concept and we analyse the impact of neutral and smiling genuine faces to the morph detector performance. The evaluation determines a detection rate of 86.0% for passport-scaled morphed images with a false alarm rate of 4.4% for genuine images for the spatial domain feature space.
Die Anzahl von mit Hilfe der Internettechnologie im Web zur Verfügung gestellten offenen API (Open APIs) zeigt ein exponentielles Wachstum. Auf der Grundlage kompositorisch zusammengesetzter APIs entstehen innovative Lösungen, die sich zunehmend als Treiber der Digitalisierung positionieren. Vor diesem Hintergrund gilt es, Open APIs aus der Perspektive der fachlichen Nutzung zu gestalten, so dass diese in möglichst vielfältigen Anwendungsszenarien stabil und nachhaltig verwendet werden können. In diesem Zusammenhang wird auch von einer „API first“-Strategie gesprochen. Die erste Session des Workshops widmet sich dieser Themenstellung, wobei u.a. auf Fragen der API-Gestaltung mit Hilfe einer OpenAPI bzw. Swagger Spezifikation eingegangen wird. Mit Aspekten des entwicklungsseitig und betrieblich benötigten API-Managements beschäftigt sich dann die zweite Session. Dabei soll sowohl auf Aspekte der Identifizierung und Authentifizierung konkreter API-Zugriffe als auch auf die Themenstellung einer DevOps-orientierten API-Bereitstellung eingegangen werden. Innovative Techniken, welche im Diskurs einer kompositorischen Softwareentwicklung verwendet werden können, stehen im Mittelpunkt der letzten Session. Dabei geht es zunächst um die durch Facebook propagierte Abfragesprache GraphQL, welche die Einbindung von httpbasierten APIs vereinfachen soll. Ein weiterer Beitrag beschreibt die Entwicklung einer mobil einsetzbaren Serviceapplikation, die umfangreichen Gebrauch von Open APIs macht. Dabei wird auf lokal installierte Entwicklungsumgebungen weitgehend verzichtet, d.h. auch diese findet Cloud-basiert statt. Der thematische Hintergrund dieses Workshops entstammt dem im letzten Jahr in Berlin durchgeführten ESAPI-Workshop (speziell dem World Café). Die Ergebnisse der dort diskutierten Fragen sind im letzten Beitrag dokumentiert.
Since its introduction in 2014, the face morphing forgery (FMF) attack has received significant attention from the biometric and media forensic research communities. The attack aims at creating artificially weakened templates which can be successfully matched against multiple persons. If successful, the attack has an immense impact on many biometric authentication scenarios including the application of electronic machine-readable travel document (eMRTD) at automated border control gates. We extend the StirTrace framework for benchmarking FMF attacks by adding five issues: a novel three-fold definition for the quality of morphed images, a novel FMF realisation (combined morphing), a post-processing operation to simulate the digital image format used in eMRTD (passport scaling 15 kB), an automated face recognition system (VGG face descriptor) as additional means for biometric quality assessment and two feature spaces for FMF detection (keypoint features and fusion of keypoint and Benford features) as additional means for forensic quality assessment. We show that the impact of StirTrace post-processing operations on the biometric quality of morphed face images is negligible except for two noise operators and passport scaling 15 kB, the impact on the forensic quality depends on the type of post-processing, and the new FMF realisation outperforms the previously considered ones.
Reducing the False Alarm Rate for Face Morph Detection by a Morph Pipeline Footprint Detector
(2018)
This paper introduces an approach to automatic generation of visually faultless facial morphs along with a proposal on how such morphs can be automatically detected. It is endeavored that the created morphs cannot be recognized as such with the naked eye and a reference automatic face recognition (AFR) system produces high similarity scores while matching a morph against faces of persons who participated in morphing. Automatic generation of morphs allows for creating abundant experimental data, which is essential (i) for evaluating the performance of AFR systems to reject morphs and (ii) for training forensic systems to detect morphs. Our first experiment shows that human performance to distinguish between morphed and genuine face images is close to random guessing. In our second experiment, the reference AFR system has verified 11.78% of morphs against any of genuine images at the decision threshold of 1% false acceptance rate. These results indicate that facial morphing is a serious threat to access control systems aided by AFR and establish the need for morph detection approaches. Our third experiment shows that the distribution of Benford features extracted from quantized DCT coefficients of JPEG-compressed morphs is substantially different from that of genuine images enabling the automatic detection of morphs.
We analyze StirTrace towards benchmarking face morphing forgeries and extending it by additional scaling functions for the face biometrics scenario. We benchmark a Benford's law based multi-compression-anomaly detection approach and acceptance rates of morphs for a face matcher to determine the impact of the processing on the quality of the forgeries. We use 2 different approaches for automatically creating 3940 images of morphed faces. Based on this data set, 86614 images are created using StirTrace. A manual selection of 183 high quality morphs is used to derive tendencies based on the subjective forgery quality. Our results show that the anomaly detection seems to be able to detect anomalies in the morphing regions, the multi-compression-anomaly detection performance after the processing can be differentiated into good (e.g. cropping), partially critical (e.g. rotation) and critical results (e.g. additive noise). The influence of the processing on the biometric matcher is marginal.
In 2014 a novel identity theft scheme targeting specific application scenarios in face biometrics was introduced. In this scheme, a so called face morph melts two or more face images of different persons into one image, which is visually similar to multiple real world persons. Based on this non authentic image, it is possible to apply for an image based identity document to be issued by a corresponding authority. Thus, multiple persons can use such a document to pass image based person verification scenarios with a single document containing an artificially weakened template. Currently there is no reliable existing security mechanism to detect this attack.
The paper presents an observation and evaluation of the recovery process. Seven weeks after the fracture of the fibula and six weeks after surgery the measurement of the gait of the subject has been started. Inertial measurement units applied above both ankles are used to acquire kinematical data and three surface EMG at each leg to get information about the activity of three muscles. The intensity of the weekly tests has been increased in dependence on the healing progress. Both scenarios-walking on the floor and on the treadmill-were included in the experiments to obtain comparable data sets. Beside of the investigation of the healing process the paper is focused on symmetry/asymmetry properties of the gait. The results indicate that asymmetry is not only an essential property of pathologic gait but it is present in normal gait too, especially if short distances are evaluated. They may be caused by the influence of a dominant/injured leg, of the first/last steps, the natural variance of the gait or the daily fitness of the subject. Asymmetry is obviously in the contribution of both legs to a stride (step length, strike and lift angle, stand and swing phase).