42 research outputs found
Photographic film and its interaction with light : detection of dust and scratches for image restoration
No full textA considerable portion of the cultural heritage of the last century is constituted by images impressed on photographic film, the majority of which are frames of motion picture films.
At present time, a large part of this heritage is at risk of being lost; this loss would break historical links, which are important for the economic, social and cultural development of future generations. The current ''digital revolution' has already produced drastic changes in image production technology, and 'classical photography' is disappearing; this leaves the field open for new powerful technical opportunities, but, at the same time, poses huge dilemmas for long-term archiving. The demise of classical photography is taking place in a precipitous and often ruinous way, causing several historied companies to go bankrupt.
Today's information society needs efficient and economic solutions for the digitization of this photographic heritage. The costs of the processes determine the amount of films that can be digitized, restored and made available to the community.
Research about digital movie restoration began around 1990, when it became possible to scan movie films in 2K resolution, thus providing high enough quality for the digitized images of a 35mm movie film. In recent years, several research projects about digital movie restoration have been undertaken. The research-project AURORA concentrated on the real-time restoration of image defects, which are typical for old videotapes; the main partners were the INA (Institut National d'Audiovisuelle, Paris), BBC-London and Snell & Wilcox, UK. PRESTO (Preservation Technology for European Archives) and the subsequent project PRESTOSPACE, within European Commission 6th Framework Programme for Research, provided technical solutions and integrated systems for a complete digital preservation of all kinds of audiovisual collections.
Audiovisual archiving is a complex and multi-disciplinary domain including such diverse fields as chemistry, physics, imaging technology, signal processing, robotics, artificial intelligence and semantic interpretation. These EU-projects bring together participants including archive owners, broadcasters, research centers from archive institutions, general research centers and universities, industries, and international non-profit institutions.
An important result of the movie restoration research is the development of new software: e.g. FRAME and its further development DIAMANT. Several early movies were reconstructed using DIAMANT, the most famous being Metropolis in 2001. LIMELIGHT was a software project that was further developed by the University of La Rochelle to become RETOUCHE.
In the period of 2010-2013, the Swiss National Science Foundation financed the project 'Dust BW: Detection of dust and scratches on photographic silver-halide (black/white) material by polarized dark-field illumination'. Partner of the project were the Imaging & Media Lab of the University of Basel and the Audiovisual Communications Laboratory School of the EPFL (École Polytechnique Fédérale de Lausanne). The present thesis reports the results of this research project.
Several factors are responsible for the deterioration of photographic material; we will only focus on dust and scratches. Different methods have been adopted up to now for the automatic detection of dust and scratches; each method has pros and cons, and a limited field of effectiveness. Infrared radiation (e.g. Digital ICE) and the spatio-temporal image analysis are among the most effective methods, although they have their limits. The infrared radiation only works for dye-based material and the spatio-temporal image analysis is not applicable for still images. The spatio-temporal image analysis is also limited due to motion in the scene and it is not effective for defects appearing in sequences spanning more than one frame (e.g. vertical scratches and lens dust). This thesis presents a comprehensive range of methods for optical flaw detection, applicable on any type of photographic film (both silver-based and dye-based material, as well as still images and moving images). It also presents innovative methods that combine different optical techniques and computational photography.
This thesis begins by describing the structure of a processed photographic film, analyzing its constitutive elements layer by layer. Afterwards, we will provide a list of the most common types of decay affecting the photographic film, classified on the basis of the layer that is primarily affected. This will be followed by a summary of the state-of-the-art strategies and solutions for the restoration of local flaws. The successive analysis of the interaction between light and photographic film provides the scientific framework needed to understand the optical phenomena involved in the experiments. The following chapter explains the phenomena and the techniques involved in imaging photographic film. A specific chapter surveys the optical methods available for flaw detection on any type of photographic transparency, including innovative solutions. The successive chapter defines the procedure we adopted for the numerical evaluation of the performances of the methods analyzed in the experiments. Prior to the conclusions, the thesis finally addresses the experimental analysis, identifying the best parameters for the proposed methods and comparing the innovative methods with the most effective traditional ones
One long image: a new approach to the creation and archiving of digital motion picture data
No full textChromatic Divide: von der Farbigwerdung medialer Repräsentation am Beispiel der Fotografie
No full textVor der digitalen Revolution war Farbe noch selten, kostbar und nicht alltäglich. Chromatic Divide beschreibt, wie die medialisierten Bilder in einem langsamen und genrespezifischen Wandel immer farbiger wurden. Die Betrachtung setzt im ausgehenden 19. Jahrhundert ein und zeigt, wie sich die Farbfotografie im Konkurrenzkampf mit anderen bunten und unbunten Vervielfältigungstechniken schrittweise etablierte. Erst mit der Digitalisierung der Druckvorstufe und dem Überhandnehmen der Bildschirmmedien wird Farbe ubiquitär.
Diese Arbeit betrachtet Farbe als technisch-kulturelles Artefakt und als ästhetisches Moment in seiner industriell-kommerziellen Rahmung. Obwohl die Art der Bildgestaltung mit Lithographien oder mit Gemälden der Moderne verglichen werden, geht es hier nicht um eine kunstwissenschaftliche Stilstudie. Es geht vielmehr um die Performanz der Farbe im massenmedialen Kontext. Der erste Teil, Farbe als Substanz, wirft einen Blick auf die Machart der Bilder und fragt nach der normierenden Kraft der massenproduzierten Farbmoleküle.
Die kostspielige Farbreproduktion erforderte hohe Investitionen und setzte hohe Auflagen voraus. Aber mit welchen Bildinhalten konnten so hohe Absätze generiert werden? Die instrumentelle Verwendung der Farbe wird am Beispiel des National Geographic Magazine von 1940 bis 2010 untersucht. Besonders interessant ist die Übergangsphase, in welcher Farbe zunächst nur selten und dann immer öfter verwendet wurde. Die Intentionalität der Verwendung wird deutlich, wenn man schaut, welche Bilder in Schwarzweiss und welche in Farbe gedruckt wurden. Der Diskurs der Farbe wird aber nicht vom Kommerz alleine gesteuert. Wie sich am National Geographic zeigen lässt, muss auch die typische Kodachrome-Farbästhetik den gesellschaftspolitischen Wandel abbilden und nimmt mit der einsetzenden Naturschutzdebatte eine dramatischen Wende
Silver mirroring on silver gelatin glass negatives
No full textSilver mirroring is a bluish metallic sheen appearing on the surface of silver based photographs as result of ageing. One of the photographic processes most affected by silver mirroring is that of silver gelatin glass negatives, the most common photographic negative process between the 1880s and the 1920s when they were slowly replaced by nitrate and acetate negatives.
The present research was initiated by the findings of plates that, beside the usual silver mirroring along the negative edges, had mirroring stains at the centre of the plate whose shape matched the creases of the glassine envelope in which the plates were stored. An informal inquiry among photographic conservators revealed that patterns connected to the enclosure material are rather common and they are not necessarily related to the poor quality of the material.
Although silver mirroring has been observed since the early years of silver gelatin photography and it has been investigated again and again in the course of the XX century, confusion is still present on its chemical composition, on the compounds responsible for its formation and on the reasons for the specific patterns.
The aim of this work is to better understand the mechanisms of both local and pattern formation of silver mirroring in order to set the choice of best suited enclosure materials and storage conditions on a more rational basis. This work is focused on silver gelatin glass negatives but the results and models here presented can be easily applied to other photographic processes exhibiting silver mirroring. The first chapter is a gallery of possible patterns found on silver gelatin glass negatives. This is first of all a visual definition of silver mirroring. Moreover, as patterns do not arise by coincidence but they are the result of simple physical processes, the visual features of silver mirroring suggest the causes for its formation.
The models about silver mirroring developed in the course of the XX century are reviewed in the second chapter. The outcome is the definition of the open questions on silver mirroring: the detailed microscopic processes leading to its local formation on one side and the macroscopic processes leading to the pattern formation on the other side.
In order to answer the first question new experiments on the chemical composition and the physical structure of the silver mirroring layer were performed. Based on these results some improvements to the well-established oxidation-migration-re-aggregation model of local silver mirroring formation are proposed in the third chapter.
The reasons for the arising of the usual silver mirroring edge patterns are investigated in the fourth chapter. A mathematical model based on the diffusion and reaction of gases explaining the formation of both historically and artificially produced edge patterns is presented.
The fifth chapter deals with the formation of inner patterns of silver mirroring. In this case, it was not possible to propose a unique model explaining the formation of the many different inner patterns that are likely to be found on silver gelatin glass negatives. The case of negatives with mirroring stains resembling the wrinkles of glassine envelopes is examined in details and a mechanism of formation is proposed.
Finally, in the conclusions, it is stated which are the contributions of this dissertation to the development of strategies to prevent or mitigate silver mirroring and which are the questions on which more research is needed
Remembering in the metaverse: preservation, evaluation, and perception
No full textElectronic memory – computing hardware and software that provides services to extend the capacity of our biological memories – can be seen as the fulfillment of the long-established vision of the MEMEX by Vannevar Bush. In a world of ubiquitous computing, our digital shadows – the proportion of our lives that has some digital representation – is no longer limited to individual documents, but reflects the continuous activities in many parts of our lives. Especially, our digital shadows are no longer isolated, but are connected to other people’s digital shadows in the space of social data and software. Based on three specific case studies, this thesis tries to develop a concept for a future metaverse archive: an electronic memory infrastructure that enables the long-term preservation, evaluation and dissemination of the information we acquire throughout our lives.
The first case study focuses on preservation and introduces the Permanent Visual Archive (PEVIAR) as a solution to digital preservation. Although electronic storage has become abundant and quite cheap, the long-term preservation of information in the digital realm still poses great challenges. While it is not yet clear whether electronic memory ought to be perfect (in contrast to the benign imperfection of our biological memories), the possibility of safely preserving information in the long term must be given. PEVIAR offers a very specific kind of electronic memory, one that is long-term stable, easily accessible, and authentic, but also very static.
The second case study focuses on the evaluation of data. It shows how social data can be used to extract the history of collectives. The email communication of 151 individuals working at the former Enron corporation (amounting to a total of around a quarter of a million of messages) is processed in order to reconstruct, visualize and analyze the social network between these individuals. It will be shown how a physical simulation is suitable for visualizing a very complex network while avoiding information overload and how this simulation not only produces the basis for a suitable visualization, but can further be used to analyze the data in combination with established graph metrics.
The third study focuses on perception and shows how context-aware display technologies (more specifically, mixed reality) are an indispensable tool in the capture, evaluation and dissemination of our digital corpora. Since much of the information we acquire is directly related to a real-world context, the recalling and consumption of this information should be able to consider this relation. We focus on spatial context to demonstrate two crucial aspects of context-aware information, namely (spatial) context detection and (spatial) context integration. The concept of hybrid images – images that contain real and virtual parts – is introduced as an example of a context-aware information system applied to the field of architecture visualization.
The three case studies are connected through their role as building blocks for a future electronic memory infrastructure, the metaverse archive. In the conclusion, we summarize the possibilities and limitations of such an archive and highlight some of the societal implications that will need to be addressed
Tagung «Bild, Code Speicher» in Basel
No full textQuelle: http://fotointer.ch Zum 60. Geburtstag von Prof. Dr. Rudolf Gschwind, Leiter des Imaging and Media Lab (IML) der Universtität Basel, führt das IML eine wissenschaftliche Tagung zum Thema «Bild, Code Speicher» durch. Dabei stehen hoch interessante Referate auf dem Programm zu «Strategien des digitalen Erinnerns», wie es im Untertitel treffend heisst. Die Tagung «Bild, Code, Speicher» reflektiert die Bedingungen, Methoden und Strategien des digitalen Erinnerns. Im Fokus stehen die digit..
Ionisierung organischer Systeme in kondensierter Phase mittels Laserblitzlicht-Photolyse und g-Bestrahlung
No full textComputational Photography for Dust and Scratch Detection on Transparent Photographic Material
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