Extracción y análisis de características para identificación, agrupamiento y modificación de la fuente de imágenes generadas por dispositivos móviles

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Informática, Departamento de Ingeniería del Software e Inteligencia Artificial, leída el 02/10/2017.Nowadays, digital images play an important role in our society. The presence of mobile devices with integrated cameras is growing at an unrelenting pace, resulting in the majority of digital images coming from this kind of device. Technological development not only facilitates the generation of these images, but also the malicious manipulation of them. Therefore, it is of interest to have tools that allow the device that has generated a certain digital image to be identified. The digital image source can be identified through the features that the generating device permeates it with during the creation process. In recent years most research on techniques for identifying the source has focused solely on traditional cameras. The forensic analysis techniques of digital images generated by mobile devices are therefore of particular importance since they have specific characteristics which allow for better results, and forensic techniques for digital images generated by another kind of device are often not valid. This thesis provides various contributions in two of the main research lines of forensic analysis, the field of identification techniques and the counter-forensics or attacks on these techniques. In the field of digital image source acquisition identification techniques, both closed and open scenarios are addressed. In closed scenarios, the images whose acquisition source are to be determined belong to a group of devices known a priori. Meanwhile, an open scenario is one in which the images under analysis belong to a set of devices that is not known a priori by the fo rensic analyst. In this case, the objective is not t he concrete image acquisition source identification, but their classification into groups whose images all belong to the same mobile device. The image clustering t echniques are of particular interest in real situations since in many cases the forensic analyst does not know a priori which devices have generated certain images. Firstly, techniques for identifying the device type (computer, scanner or digital camera of the mobile device) or class (make and model) of the image acquisition source in mobile devices are proposed, which are two relevant branches of forensic analysis of mobile device images. An approach based on different types of image features and Support Vector Machine as a classifier is presented. Secondly, a technique for the ident ification in open scenarios that consists of grouping digital images of mobile devices according to the acquisition source is developed, that is to say, a class-grouping of all input images is performed. The proposal is based on the combination of hierarchical grouping and flat grouping using the Sensor Pattern Noise. Lastly, in the area of att acks on forensic t echniques, topics related to the robustness of the image source identificat ion forensic techniques are addressed. For this, two new algorithms based on the sensor noise and the wavelet transform are designed, one for the destruction of t he image identity and another for its fo rgery. Results obtained by the two algorithms were compared with other tools designed for the same purpose. It is worth mentioning that the solution presented in this work requires less amount and complexity of input data than the tools to which it was compared. Finally, these identification t echniques have been included in a tool for the forensic analysis of digital images of mobile devices called Theia. Among the different branches of forensic analysis, Theia focuses mainly on the trustworthy identification of make and model of the mobile camera that generated a given image. All proposed algorithms have been implemented and integrated in Theia thus strengthening its functionality.Actualmente las imágenes digitales desempeñan un papel importante en nuestra sociedad. La presencia de dispositivos móviles con cámaras fotográficas integradas crece a un ritmo imparable, provocando que la mayoría de las imágenes digitales procedan de este tipo de dispositivos. El desarrollo tecnológico no sólo facilita la generación de estas imágenes, sino también la manipulación malintencionada de éstas. Es de interés, por tanto, contar con herramientas que permitan identificar al dispositivo que ha generado una cierta imagen digital. La fuente de una imagen digital se puede identificar a través de los rasgos que el dispositivo que la genera impregna en ella durante su proceso de creación. La mayoría de las investigaciones realizadas en los últimos años sobre técnicas de identificación de la fuente se han enfocado únicamente en las cámaras tradicionales. Las técnicas de análisis forense de imágenes generadas por dispositivos móviles cobran, pues, especial importancia, ya que éstos presentan características específicas que permiten obtener mejores resultados, no siendo válidas muchas veces además las técnicas forenses para imágenes digitales generadas por otros tipos de dispositivos. La presente Tesis aporta diversas contribuciones en dos de las principales líneas del análisis forense: el campo de las t écnicas de identificación de la fuente de adquisición de imágenes digitales y las contramedidas o at aques a est as técnicas. En el primer campo se abordan tanto los escenarios cerrados como los abiertos. En el escenario denominado cerrado las imágenes cuya fuente de adquisición hay que determinar pertenecen a un grupo de dispositivos conocidos a priori. Por su parte, un escenario abierto es aquel en el que las imágenes pertenecen a un conjunto de dispositivos que no es conocido a priori por el analista forense. En este caso el obj etivo no es la identificación concreta de la fuente de adquisición de las imágenes, sino su clasificación en grupos cuyas imágenes pertenecen todas al mismo dispositivo móvil. Las técnicas de agrupamiento de imágenes son de gran interés en situaciones reales, ya que en muchos casos el analist a forense desconoce a priori cuáles son los dispositivos que generaron las imágenes. En primer lugar se presenta una técnica para la identificación en escenarios cerrados del tipo de dispositivo (computador, escáner o cámara digital de dispositivo móvil) o la marca y modelo de la fuente en dispositivos móviles, que son dos problemáticas relevantes del análisis forense de imágenes digitales. La propuesta muestra un enfoque basado en distintos tipos de características de la imagen y en una clasificación mediante máquinas de soporte vectorial. En segundo lugar se diseña una técnica para la identificación en escenarios abiertos que consiste en el agrupamiento de imágenes digitales de dispositivos móviles según la fuente de adquisición, es decir, se realiza un agrupamiento en clases de todas las imágenes de ent rada. La propuesta combina agrupamiento jerárquico y agrupamiento plano con el uso del patrón de ruido del sensor. Por último, en el área de los ataques a las técnicas fo renses se tratan temas relacionados con la robustez de las técnicas forenses de identificación de la fuente de adquisición de imágenes. Se especifican dos algoritmos basados en el ruido del sensor y en la transformada wavelet ; el primero destruye la identidad de una imagen y el segundo falsifica la misma. Los resultados obtenidos por estos dos algoritmos se comparan con otras herramientas diseñadas para el mismo fin, observándose que la solución aquí presentada requiere de menor cantidad y complejidad de datos de entrada. Finalmente, estas técnicas de identificación han sido incluidas en una herramienta para el análisis forense de imágenes digitales de dispositivos móviles llamada Theia. Entre las diferentes ramas del análisis forense, Theia se centra principalmente en la identificación confiable de la marca y el modelo de la cámara móvil que generó una imagen dada. Todos los algoritmos desarrollados han sido implementados e integrados en Theia, reforzando así su funcionalidad.Depto. de Ingeniería de Software e Inteligencia Artificial (ISIA)Fac. de InformáticaTRUEunpu

Navigating the roadblocks to spectral color reproduction: data-efficient multi-channel imaging and spectral color management

Commercialization of spectral imaging for color reproduction will require the identification and traversal of roadblocks to its success. Among the drawbacks associated with spectral reproduction is a tremendous increase in data capture bandwidth and processing throughput. Methods are proposed for attenuating these increases with data-efficient methods based on adaptive multi-channel visible-spectrum capture and with low-dimensional approaches to spectral color management. First, concepts of adaptive spectral capture are explored. Current spectral imaging approaches require tens of camera channels although previous research has shown that five to nine channels can be sufficient for scenes limited to pre-characterized spectra. New camera systems are proposed and evaluated that incorporate adaptive features reducing capture demands to a similar few channels with the advantage that a priori information about expected scenes is not needed at the time of system design. Second, proposals are made to address problems arising from the significant increase in dimensionality within the image processing stage of a spectral image workflow. An Interim Connection Space (ICS) is proposed as a reduced dimensionality bottleneck in the processing workflow allowing support of spectral color management. In combination these investigations into data-efficient approaches improve two critical points in the spectral reproduction workflow: capture and processing. The progress reported here should help the color reproduction community appreciate that the route to data-efficient multi-channel visible spectrum imaging is passable and can be considered for many imaging modalities

Monen näkymän stereon rekonstruktio tietokonegrafiikan sisällön taltiointiin

Rendering of photorealistic models is becoming increasingly feasible and important in computer graphics. Due to the high amount of work in creating such models by hand, required by the need of high level of detail in geometry, colors, and animation, it is desirable to automate the model creation. This task is realised by recovering content from photographs that describe the modeled subject from multiple viewpoints. In this thesis, elementary theory on image acquisition and photograph-based reconstruction of geometry and colors is studied and recent research and software for graphics content reconstruction are reviewed. Based on the studied background, a rig is built as a grid of nine off-the-shelf digital cameras, a custom remote shutter trigger, and supporting software. The purpose of the rig is to capture high-quality photographs and video in a reliable and practical manner, to be processed in multi-view reconstruction programs. The camera rig was configured to shoot small static subjects for experiments. The resulting photos and video were then processed directly for the subject's geometry and color, with little or no image enhancements done. Two typical reconstruction software pipelines were described and tested. The rig was found to perform well for several subjects with little subject-specific tuning; issues in the setup were analyzed and further improvements suggested based on the captured test models. Image quality of the cameras was found to be excellent for the task, and most problems arose from uneven lighting and practical issues. The developed rig was found to produce sub-millimeter scale accuracy in geometry and texture of subjects such as human faces. Future work was suggested for lighting, video synchronization and study of state-of-the-art image processing and reconstruction algorithms.Fotorealististen mallien renderöinti on yhä tärkeämpää ja mahdollisempaa tietokonegrafiikassa. Näiden mallien luominen käsityönä on työlästä vaaditun korkean tarkkuuden takia geometrian, värien ja animaation osalta, ja onkin haluttavaa korvata käsityö automatiikalla. Automatisointi voidaan suorittaa taltioimalla sisältö valokuvista, jotka kuvastavat samaa kohdetta useammasta näkymästä. Tässä diplomityössä tarkastellaan kuvantamista ja valokuvapohjaisen geometrian rekonstruktiota geometrian ja värien kannalta ja katsastetaan viimeaikainen tutkimus ja ohjelmistot grafiikkasisällön rekonstruointiin. Taustan pohjalta rakennetaan laitteisto, joka koostuu yhdeksästä valmiina saatavilla olevasta digikamerasta aseteltuna hilaksi, itse tehdystä etälaukaisimesta sekä ohjelmistoista. Laitteiston tarkoituksena on taltioida luotettavalla ja käytännöllisellä tavalla korkealaatuisia valokuvia ja videokuvaa, joita voi käsitellä monen näkymän stereon rekonstruktion tietokonesovelluksissa. Laitteisto säädettiin kuvaamaan pieniä staattisia kohteita kokeita varten. Tuloksena saadusta kuvamateriaalista laskettiin kohteen geometria ja värit ilman mainittavaa kuvanparannuksen käyttöä. Käytiin läpi kaksi tyypillistä rekonstruktio-ohjelmistoa testiksi ja laitteiston havaittiin soveltuvan hyvin useisiin kohteisiin ilman erityistä säätämistä. Kameroiden kuvanlaatu todettiin tehtävään erinomaiseksi ja useimmat haasteet johtuivat epätasaisesta valaistuksesta ja käytännön pulmista. Laitteiston todettiin tuottavan alle millimetriskaalan geometriaa ja pintavärikuvaa ihmiskasvojen kaltaisista kohteista. Jatkotyötä ehdotettiin valaistukseen, videon synkronointiin ja viimeisimpien kuvankäsittely- ja rekonstruktioalgoritmien tutkimiseen

Broadband radio mapping and imaging of lightning processes

Though thunderstorms and lightning are commonplace on Earth, it is still unclear how lightning initiates, propagates, and how it is involved in generating intense bursts of gamma-rays that can be detected by spacecraft. Lightning is a hot, highly-ionized plasma channel, capable of carrying up to hundreds of kiloamperes electric current, and extending many kilometers in length for hundreds of milliseconds at a time. Despite its immensity, lightning can be difficult to observe, as it primarily initiates and propagates deep within thunderclouds, optically obscured by thousands of cubic kilometers of cloud water and ice. Broadband radio interferometry has been developed to study lightning at radio frequencies, offering us a way to “see” inside the clouds. The technique, which is still in its infancy for lightning research, allows for lightning radio emissions to be mapped and/or imaged with extremely fine time resolution. In this dissertation, a newly-developed three-element, broadband VHF (~14-88 MHz), 16-bit radio interferometer (INTF) is used to investigate extremely transient thunderstorm electrical phenomena involved in lightning initiation, propagation, and high-energy photon production. The investigations demonstrate the novel science that can be done with the INTF system, and reveal previously unforeseen dynamics of lightning formation. Specifically, we image and map the VHF emissions of narrow bipolar events (NBEs), initial breakdown pulses (IBPs), and an energetic in-cloud pulse (EIP) with sub-microsecond resolution. NBEs have long been of interest to the lightning community because they are the most powerful natural emitters of high-frequency and very-high-frequency radio waves on Earth. Moreover, NBEs are readily identifiable by their narrow (~10 µs wide), bipolar sferics (~3 kHz-3 MHz radio emissions). NBEs are not lightning, but appear to be a precursor to lightning, occurring either in complete isolation, or at the beginning of a lightning flash. IBPs, in contrast, never occur in isolation, but rather are the hallmark of lightning channel formation. IBPs typically occur in long trains of sferic pulses, and indicate the imminence of lightning during the first milliseconds after lightning initiation. An IBP is also identified by its sferic, having a bipolar waveform some tens of microseconds wide, the initial pulse of which is superimposed by ~1 µs-wide subpulses. Lastly, EIPs are high-peak-current (\u3e200 kA) events that are involved in the generation of terrestrial gamma-ray flashes (TGFs), which are intense bursts of gamma-rays that radiate out the tops of thunderclouds and are detected in space. EIPs have a signature high-amplitude, ~50 µs-wide sferic, which is time-aligned with satellite-borne gamma-ray detections. EIPs can thus serve as a proxy for TGFs, offering a way to investigate TGFs using ground-based radio sensors, without necessarily needing satellite data. The physical natures of NBEs, IBPs, and EIPs have been active areas of research over the last decade. For over half a century, the role that IBPs play in initial hot channel formation has been under debate. More recently, intense investigation has been focused on exactly how NBEs are involved in lightning initiation. Just in the last few years, EIPs were discovered, offering a new way to investigate the role that lightning plays in TGF generation. By investigating NBEs with the INTF, we discovered a newly-identified form of streamer-based breakdown, termed fast negative breakdown, that does not fit with our current understanding of lightning initiation. Streamers are cold filamentary plasma channels, and based on conventional dielectric theory, it was hypothesized that lightning should be initiated by positive streamers, which carry electric current in their propagation direction. However, fast negative breakdown carries electric current opposite its propagation direction, propagating ~500 m through virgin air with an unusually fast speed of ~10^7 m/s. Aside from breakdown polarity, fast negative breakdown is in many ways similar to recently reported fast positive breakdown that generates the majority of NBEs, and that is expected from conventional dielectric theory. We additionally show that similarly fast breakdown is involved in the production of both IBPs and EIPs. Using the INTF, we show that the IBP process is dominated by a fast-propagating ∼10^7 m/s streamer-based negative breakdown that propagates the channel about ~100 m into virgin air, similar to the fast negative breakdown associated with NBEs. We show that the streamer-based channel extension leads to a sustained electric current, indicating the existence of a hot conductive lightning channel. Fast-propagating ~10^7-10^8 m/s breakdown of both polarities is also a prominent feature during the EIP, but occurs over a larger (\u3e1-km altitude) volume than during NBEs or IBPs. We show that repeated downward- and upward-propagating fast positive and negative breakdown are somehow coupled to the generation of relativistic electrons and associated ionization. We conclude that the electric current that produces the EIP sferic is generated by a newly discovered type of self-sustaining discharge termed a relativistic feedback discharge (RFD), which involves multiple generations of relativistic electron avalanches and back-scattered positrons and X-rays. Our study further demonstrates that TGFs can be produced by RFDs. The INTF was developed by New Mexico Tech, and deployed and operated at Kennedy Space Center (KSC) in Florida during summer 2016 to obtain the data used herein

Image source identification and characterisation for forensic analysis

Digital imaging devices, such as digital cameras or mobile phones, are prevalent in society. The images created by these devices can be used in the commission of crime. Source device identification is an emerging research area and involves the identification of artefacts that are left behind in an image by the camera pipeline. These artefacts can be used as digital signatures to identify the source device forensically. The type of digital signature considered in this thesis is the Sensor Pattern Noise (SPN), which consists mainly of the PRNU (Photo Response Non-Uniformity) of the imaging device. The PRNU is unique to each individual sensor, which can be extracted traditionally with a wavelet denoising filter and enhanced to attenuate unwanted artefacts. This thesis proposes a novel method to extract the PRNU of a digital image by using Singular Value Decomposition (SVD) to extract the digital signature. The extraction of the PRNU is performed using the homomorphic filtering technique, where the inherently nonlinear PRNU is transformed into an additive noise. The range of the energy of the PRNU is estimated, which makes it easier to separate from other polluting components to obtain a cleaner signature, as compared to extracting all the high frequency signals from an image. The image is decomposed by using SVD, which separates the image into ranks of descending order of energies. The estimated energy range of the PRNU is used to obtain the interesting ranks that are utilised to form part of the digital signature. A case study of an existing image analyser platform was performed by investigating its identification and classification results. The SVD based extraction method was tested by extracting image signatures from camera phones. The results of the experiments show that it is possible to determine the source device of digital images

Benchmarking of mobile phone cameras

fi=vertaisarvioitu|en=peerReviewed

Explosive Transient Camera (ETC) Program

Since the inception of the ETC program, a wide range of new technologies was developed to support this astronomical instrument. The prototype unit was installed at ETC Site 1. The first partially automated observations were made and some major renovations were later added to the ETC hardware. The ETC was outfitted with new thermoelectrically-cooled CCD cameras and a sophisticated vacuum manifold, which, together, made the ETC a much more reliable unit than the prototype. The ETC instrumentation and building were placed under full computer control, allowing the ETC to operate as an automated, autonomous instrument with virtually no human intervention necessary. The first fully-automated operation of the ETC was performed, during which the ETC monitored the error region of the repeating soft gamma-ray burster SGR 1806-21

Transdisciplinary Creative Ecologies in Contemporary Art within Emergent Processes

This research is composing in the moving with affective speeds and rhythms, instead of unfolding direct and in linear ways. It is important to come across different planes of composition in movement. There are so many planes of voices spinning around in relation. Research-creation seems as forms of relations and an invitation to appreciate the collectivity at the heart of thinking. The many entering-into relation within a differential thought in the making of its own. Emergent properties in non-human interactions, such as those presented in Steven Shaviro ́s Against Self-Organization (2009) and Brain Massumi, are symptomatic of how individualities relate to creative tendencies in relation to the human, non-human dynamism, and emergence as a state or condition. Emergence can be co-joined around the notion of self-organization, “the spontaneous production of a level of reality having its own rules of formation and order of connection” (Massumi, 2002). Self-organization emphasizes on matter-energy which Gilles Deleuze conceives of as the difference or line variation running through all things. Therefore, Deleuze focuses on immanence, how new forms are created, and on the ways in which material bodyings self-organize rather than being forced to do so. Moreover, the research in this dissertation seeks to generate a charged environment where human and non-human emergent processes activate creative encounters that co-create and co-shape each other (Delueze and Guattari, 2003; Stangers, 2017; Manning 2009). This study investigates how complexities and relations expand as an attractor of potentialities, that informs a matrix as movement, and recognizes nodes of the matrix as connections for such movements. My research is transdisciplinary, where experimental work interconnects art, science- zoology, architecture and process philosophy, and conjoins such with non-human emergent processes which are complex systems that activate intermodalities in their doing. These areas of research focus on, thread processes and transdisciplinary art doings.Textiles seen as intensities, transformations, movements, multiplicities of sensations experienced by familiar bodies in resonance with the world in acts of co-composing