L'objectif est de développer un guillochage de photographie inspiré de l'holographie numérique en ligne, capable d'encoder la signature issue d'un hachage robuste de l'image (méthode de Mihçak et Venkatesan). Une telle combinaison peut permettre l'authentification de l'image guillochée dans le domaine numérique, le cas échéant après impression. Cette approche contraint le hachage à être robuste au guillochage. La signature est codée en un nuage de formes que l'on fait virtuellement diffracter pour former la marque à insérer (guilloches dites de Fresnel) dans l'image originale. Image dense, cette marque est insérée de façon peu, voire non visible afin de ne pas gêner la perception du contenu de la photographie mais de façon à pouvoir ultérieurement lire la signature encodée en vue de la comparer à la signature de la photographie à vérifier. L'impression-lecture rend la tâche plus difficile. Le guillochage de Fresnel et l'authentification associée sont testés sur une banque (réduite) d'images / This work aims to develop a new type of guilloché pattern to be inserted in a photograph (guillochage), inspired from in-line digital holography and able to encode an image robust hash value (méthode de Mihçak et Venkatesan). Such a combination can allow the authentication of the image including the guilloché pattern in the digital domain and possibly in the print domain. This approach constraints image hashing to be robust to guillochage. The hash value is encoded as a cloud of shapes that virtually produces a diffraction”pattern to be inserted as a mark (named “guilloches de Fresnel“) in the original image. The image insertion results from a trade off : the high-density mark should be quite or even not visible in order to avoid any disturbance in the perception of the image content but detectable in order to be able to compare the decoded hash to the hash of the current photograph. Print and scan makes the task harder. Both the Fresnel guillochage and the associated authentication are tested on a (reduced) image database

The objects discovered in Tomb 79 at the necropolis of Salamis, Cyprus have garnered much attention since their discovery. The material from this tomb, however, needs an in-depth, object-by-object analysis that will lead to a greater understanding of the burial as a whole. In my thesis, I offer a detailed case study of a single item, an ivory-covered wooden chair—so-called Throne Γ—as exemplifying an approach to this analysis. Based on the excavation team’s exacting reconstruction, the chair is four-legged with armrests and a slightly curved backrest. Ivory overlays the entirety of the chair except on a few sections of the backrest where the wood shows through. Here as well, both figural and geometric designs decorate the ivory, and the top bar was originally overlaid with gold. As a whole, Throne Γ would have appeared as a solid ivory object, embellished with wood and gold, and was likely draped with textiles. In this study, I analyze Throne Γ as an agent of identity. To do so, I follow the example of other scholars such as Irene Winter and Marian Feldman and employ the theory of object agency, addressing Throne Γ as an affective entity. When placed in a social context—i.e., when involved in human interaction—such agentive objects actively influence their surroundings. In this case, I analyze how Throne Γ affected the individual in whose tomb it was buried. I argue that through its various affective “mechanisms”—its nature as a luxury object, the value of its ivory material, its sensory qualities (including luminosity, texture, and fragrance), its iconography, and its ritual function—Throne Γ projected a king-like identity upon the deceased individual from Tomb 79. His actual political and social power during his lifetime, however, may have been less than that suggested by the mechanisms of the chair. The inclusion of Throne Γ in the burial was therefore a conscious choice and the identity the chair projected deliberate. It was meant to agentively mark, and thus legitimize, the deceased as a politically-able, diplomatically-savvy, and divinely-touched figure in the early days of monarchy on Cyprus. / text

L'objectif est de développer un guillochage de photographie inspiré de l'holographie numérique en ligne, capable d'encoder la signature issue d'un hachage robuste de l'image (méthode de Mihçak et Venkatesan). Une telle combinaison peut permettre l'authentification de l'image guillochée dans le domaine numérique, le cas échéant après impression. Cette approche contraint le hachage à être robuste au guillochage. La signature est codée en un nuage de formes que l'on fait virtuellement diffracter pour former la marque à insérer (guilloches dites de Fresnel) dans l'image originale. Image dense, cette marque est insérée de façon peu, voire non visible afin de ne pas gêner la perception du contenu de la photographie mais de façon à pouvoir ultérieurement lire la signature encodée en vue de la comparer à la signature de la photographie à vérifier. L'impression-lecture rend la tâche plus difficile. Le guillochage de Fresnel et l'authentification associée sont testés sur une banque (réduite) d'images