Robustness of a DFT based image watermarking method against am halftoning

U ovom radu je evaluirana otpornost na rastriranje metode označavanja slika bazirane na diskretnoj Fourierovoj transformaciji (DFT). Rastriranje se koristi za reprodukciju višetonskih slika. U istraživanju je korišten set od 1000 slika. Za rastriranje su korištena tri različita oblika rasterskog elementa (točka, elipsa i linija) i 5 različitih linijatura (10, 13, 15, 40 i 60 lin/cm). Evaluirana je vjerojatnost detekcije i distribucija postignutih vrijednosti detekcije. Rezultati su pokazali da je ispitivana metoda označavanja slika otporna na rastriranje linijaturama većim od 15 lin/cm. Također, zaključeno je da oblik rasterskog elementa ima slab utjecaj na stupanj detekcije.In this paper the robustness of a Discrete Fourier Transform (DFT) based image watermarking scheme to amplitude modulation (AM) halftoning is evaluated. Halftoning is used for reproduction of continuous images. Thus, it is important that a watermarking method is robust to halftoning. Three different shapes of clustered dots of AM (Amplitude Modulation) halftones are used (round, ellipse and line) with five different halftone frequencies (10, 13, 15, 40, and 60 line/cm). The tests where done on a dataset of 1000 images. As the metric of robustness, watermark detection rate, distribution of detection values, and ROC (Receiver Operation Characteristic) curves were used. The results showed that the watermarking scheme is robust to halftoning for halftone frequencies greater than 15 line/cm. Also, the type of AM halftone used has almost no effect on a detection rate

Robustness of a DFT based image watermarking method against am halftoning

U ovom radu je evaluirana otpornost na rastriranje metode označavanja slika bazirane na diskretnoj Fourierovoj transformaciji (DFT). Rastriranje se koristi za reprodukciju višetonskih slika. U istraživanju je korišten set od 1000 slika. Za rastriranje su korištena tri različita oblika rasterskog elementa (točka, elipsa i linija) i 5 različitih linijatura (10, 13, 15, 40 i 60 lin/cm). Evaluirana je vjerojatnost detekcije i distribucija postignutih vrijednosti detekcije. Rezultati su pokazali da je ispitivana metoda označavanja slika otporna na rastriranje linijaturama većim od 15 lin/cm. Također, zaključeno je da oblik rasterskog elementa ima slab utjecaj na stupanj detekcije.In this paper the robustness of a Discrete Fourier Transform (DFT) based image watermarking scheme to amplitude modulation (AM) halftoning is evaluated. Halftoning is used for reproduction of continuous images. Thus, it is important that a watermarking method is robust to halftoning. Three different shapes of clustered dots of AM (Amplitude Modulation) halftones are used (round, ellipse and line) with five different halftone frequencies (10, 13, 15, 40, and 60 line/cm). The tests where done on a dataset of 1000 images. As the metric of robustness, watermark detection rate, distribution of detection values, and ROC (Receiver Operation Characteristic) curves were used. The results showed that the watermarking scheme is robust to halftoning for halftone frequencies greater than 15 line/cm. Also, the type of AM halftone used has almost no effect on a detection rate

From map to mapping: imaging active landscapes through 'figure' and 'ground'

The research builds on and contributes to the representation in landscape, specifically the imaging of active landscapes. Current representational methodologies in landscape architecture have already defined various regimes for the mapping of landscapes. Most of these operate by portraying existing conditions that prioritize visual and formal qualities, displacing objects from their wider context and creating neutral artificialities. Although the discourse of representation has already emphasized the need for appropriate methodologies that engage more closely with the landscape, there has not been an examination and production of techniques that not only privilege the object but also encourage the imaginative conception of experiential phenomena unfolding over time. A convention such as the figure-ground plan is an idealized and dominant technique that expresses an existing cond ition, without references to evolution or change. This research provides additional insight into the depiction of events that develop over time by reconceptualising "figure" and "ground" as mutualistic entities rather than hierarchical and biased conditions. It demonstrates that figure and ground are but interdependent and coordinated concepts by depicting them in patterns with variant scales, colours and textures. These shift landscape representation from appearance to composition, from description to narration, forming chains of information that lack regularity and stability, and which inform the deviating course of phenomena in the landscape. The analytic focus on mapping enables various contributions: firstly it allows imaging the incessant construction of landscape rather than its portrayal as an empty, dead event. The communicated perception of a changing landscape permits a more inclusive appreciation of its development and staging: understanding how things work aids in developing ways to choreograph what they may become. Secondly, the maps outcomes not only depict or represent images, but facilitate a visualization of the performative qualities of landscape elements - their processes, events, affective phenomena, etc. This means that the viewer is not only an external observer but is able to participate in a shared experience of apprehending a given landscape. This method of communication uses various scales and colours to manipulate perception and give multiple meanings depending on an experiential engagement with the representation. The work evaluates the participation of representation in design by using real experimental cases from three international design competitions. The importance of the research relies not only in mapping outcomes, but in its inquisitive production that reconceptualises "figure" and "ground". The figure-ground map provides a laboratory for graphic experimentation by developing series of patterns and moirés that addressed temporal phenomena and irregularities in landscape systems. The research project does not aim to simply produce experimental graphic compositions, but to use figure-ground mechanisms to structure processes and phenomena. This approach unveils the potential of institutionalized representation techniques and exposes their ability in facilitating visualization of active landscapes

ID Photograph hashing : a global approach

This thesis addresses the question of the authenticity of identity photographs, part of the documents required in controlled access. Since sophisticated means of reproduction are publicly available, new methods / techniques should prevent tampering and unauthorized reproduction of the photograph. This thesis proposes a hashing method for the authentication of the identity photographs, robust to print-and-scan. This study focuses also on the effects of digitization at hash level. The developed algorithm performs a dimension reduction, based on independent component analysis (ICA). In the learning stage, the subspace projection is obtained by applying ICA and then reduced according to an original entropic selection strategy. In the extraction stage, the coefficients obtained after projecting the identity image on the subspace are quantified and binarized to obtain the hash value. The study reveals the effects of the scanning noise on the hash values of the identity photographs and shows that the proposed method is robust to the print-and-scan attack. The approach focusing on robust hashing of a restricted class of images (identity) differs from classical approaches that address any imageCette thèse traite de la question de l’authenticité des photographies d’identité, partie intégrante des documents nécessaires lors d’un contrôle d’accès. Alors que les moyens de reproduction sophistiqués sont accessibles au grand public, de nouvelles méthodes / techniques doivent empêcher toute falsification / reproduction non autorisée de la photographie d’identité. Cette thèse propose une méthode de hachage pour l’authentification de photographies d’identité, robuste à l’impression-lecture. Ce travail met ainsi l’accent sur les effets de la numérisation au niveau de hachage. L’algorithme mis au point procède à une réduction de dimension, basée sur l’analyse en composantes indépendantes (ICA). Dans la phase d’apprentissage, le sous-espace de projection est obtenu en appliquant l’ICA puis réduit selon une stratégie de sélection entropique originale. Dans l’étape d’extraction, les coefficients obtenus après projection de l’image d’identité sur le sous-espace sont quantifiés et binarisés pour obtenir la valeur de hachage. L’étude révèle les effets du bruit de balayage intervenant lors de la numérisation des photographies d’identité sur les valeurs de hachage et montre que la méthode proposée est robuste à l’attaque d’impression-lecture. L’approche suivie en se focalisant sur le hachage robuste d’une classe restreinte d’images (d’identité) se distingue des approches classiques qui adressent une image quelconqu

Characterization and identification of printed objects

A study about the physical appearance of pre-photographic, photomechanical, photographic and digital positive reflective prints was made, relating the obtained images with the history, materials and technology used to create them. The studied samples are from the Image Permanence Institute (IPI) study collection. The digital images were obtained using a digital SLR on a copystand and a compound light microscope, with different lighting angles (0º, 45ºand 90º) and magnifications from overall views on the copystand down to a 20x objective lens on the microscope. Most of these images were originally created by IPI for www.digitalsamplebook.org, a web tool for teaching print identification, and will be used on the www.graphicsatlas.org website, along with textual information on identification, technology and history information about these reproduction processes

Maturation of Practices

The disparate concepts of Pop Art and abstract painting heavily influence the scope of my work. Finding a link between these two concepts has been the focal point of my studio practices. The apex of my process is the focus on commercial imagery as abstract form. The merging of these two concepts presents a complex composition of balance, color and information. This thesis explores the various concepts as well as influences that have propelled the evolution of my work. It chronicles the steps I have taken in my quest to articulate my conceptual ideas. By describing the works and defining their characteristics, this analysis gives further insight to my perception as well as process

The Physicality of Print

Printmaking within the applied arts is an extremely diverse practice that can extend the concept of what a print can be. Rather than the dissemination of published images and text, in this context printed information is transformed into objects and materials, ceramics, textiles, tableware, clothing. Prints such as these are not ʻreproductionʼ they are ʻproductionʼ.Process is crucial to both printmaking and the applied arts and the determining aspect of production plays a vital part in defining the qualities of a work such as print-decorated ceramic objects. To work with a printmaking process in this sector requires interpretation, predictive foresight and a degree of ʻthinking-through-makingʼ to transpose an image into the physical world of materials and objects. Printmaking, specifically within the ceramic discipline, is often plagued by issues of integrity brought about by problems relating to ʻdivisionʼ, these issues include: - - The physical divisions between image and object - The divided tasks in production that can disrupt thinking and making - A division of perceptions surrounding the surface/form relationship that considers the surface as supplementary or artificial Commercial production has developed approaches and techniques to integrate surface and form, combat these negative perceptions and raise the value of this type of work. These methods are not, however, always appropriate or accessible to individual ceramist-printmakers working in the studio. How can this sector overcome these negative factors and adopt strategies that invest some value of visual integrity within production? The research project answers this question in two ways: A low-tech, accessible method was developed in the studio with the aim to offer a new practical approach that physically integrates complex ceramic forms with the printed image. The aim was to facilitate this unity at an early ʻraw-clayʼ stage, where the combined manipulation of surface and form can take place together, resulting in an aesthetic that has ʻvisual integrityʼ. The second aim of the research has been to identify the inherent qualities of working and thinking ʻwithinʼ the language of ceramics and print materials and processes. ʻSyntacticʼ qualities and factors have been determined through research into historical innovations and the observation of current commercial practice in the field of screenprinting and screenprinted ceramics. This has helped to establish approaches to overcome negative factors relating to the perception of division, and invest integrity in the work through principled approaches to practice. The project adopts a methodology of ʻthinking-through-makingʼ where iterative studio experimentation is undertaken through tacit understanding, gained from experiential knowledge combined with research of contemporary and historical precedents. This approach is reflected upon and informed by writers who discuss working within the inherent language of printmaking. The research contributes to the advancement of knowledge through the development of a new versatile technique that can be easily accessed by ceramists and printmakers who wish to produce integrated ceramics and print works. This contributes to the advancement of technology, perception and knowledge in the field of printed ceramic objects. My approach and the development of a value system also offers a tool to further the critica

Tribeless

Looking into the role of craft a vessel for cultural creation. Specifically focus on tattooing and printmaking as methods