<div>Steganalysis is the study of detecting secret information hidden in objects such as images, videos, texts, time series and games via steganography. Among those objects, the image is the most widely used object to hide secret messages. Detection of possible secret information hidden in images has attracted a lot of attention over the past ten years. People may conduct covert communications by exchanging images in which secret messages may be embedded in bits. One of main advantages of steganography over cryptography is that the former makes this communication insensible for human beings. So statistical methods or tools are needed to help distinguish cover images from stego images. <br></div><div><br></div><div>In this thesis, we start with a discussion of image steganography. Different kinds of embedding schemes for hiding secret information in images are investigated. We also propose a hiding scheme using a reference matrix to lower the distortion caused by embedding. As a result, we obtain Peak Signal-to-Noise Ratios (PSNRs) of stego images that are higher than those given by a Sudoku-based embedding scheme. Next, we consider statistical steganalysis of images in two different frameworks. We first study staganalysis in the framework of statistical hypothesis testing. That is, we cast a cover/stego image detection problem as a hypothesis testing problem. For this purpose, we employ different statistical models for cover images and simulate the effects caused by secret information embedding operations on cover images. Then the staganalysis can be characterized by a hypothesis testing problem in terms of the embedding rate. Rao’s score statistic is used to help make a decision. The main advantage of using Rao’s score test for this problem is that it eliminates an assumption used in the previous work where approximated log likelihood ratio (LR) statistics were commonly employed for the hypothesis testing problems.<br></div><div><br></div><div>We also investigate steganalysis using the deep learning framework. Motivated by neural network architectures applied in computer vision and other tasks, we propose a carefully designed a deep convolutional neural network architecture to classify the cover and stego images. We empirically show the proposed neural network outperforms the state-of-the-art ensemble classifier using a rich model, and is also comparable to other convolutional neural network architectures used for steganalysis.<br></div><div><br></div>The image databases used in the thesis are available on websites cited in the thesis. The stego images are generated from the image databases using source code from the website. <a href="http://dde.binghamton.edu/download/">http://dde.binghamton.edu/download/</a>

科技在過去十多年的迅速發展，成就了電腦及互聯網絡的普及，將人類推向一個未知的新紀元。我們正處於一個影像數量前所未有地泛濫、流通的時代，更多影像媒體的出現，導致我們對於觀看的方式有了新的體驗。視覺媒介與及影像長久以來也在藝術創作、以至人類文明中佔據著主導地位，作為當代藝術家如何對應這個時代的科技與影像文化變遷？本文從三個章節去探討當代藝術創作在數位科技下對新媒體影像的探討與反思。一）影像的定義與科技發展的歷史脈絡：先探討當下數位影像跟觀看方式的轉變，透過檢視影像建構意義的過程去確立一個討論的環境前提；並追朔媒體與空間概念跟影像科技發展的歷史脈絡。二）新媒體與數位影像：界定新媒體的定義，及其發展對影像意義、角色定位所帶來的轉變；延伸至當下虛擬與真實的空間概念轉變。三）非物質的物質化呈現：以當代藝術創作為例子，去闡述新媒體影像及其媒介平台在當代生活中的各種面向。本章所論述的藝術創作集中在以傳統媒介為基礎去對應新媒體影像的藝術作品，而非以新媒體本身為作品媒介的「新媒體藝術創作」。在文末附以本人的藝術作品以供參考。 / The rapid development in technology caused the popularization of computers and internet over the past decades and it generated a new era to human beings. We are at the age of unprecedented number of image, the new visual media has led to a new way of looking. Images and visual media have long been a dominant position in art and human civilization, how to respond with this era of technology and visual culture change as a contemporary artist becomes an important issue. This thesis is divided into three chapters which aim at exploring contemporary artistic creation, discussion and reflection of images of the new media in the digital technology. 1) The definition of image through historical context and development of visual technology: The first phase discusses the change on the way of looking according to the present digital images, the process of constructing meaning through looking the image are introduced to establish a background for the discussion; and traced the historical context of media technology with image development. 2) Of the digital images and new media: The second phase defines the definition of new media, and its influence on the meaning and role of extends to the changes in the concept of virtuality and real space. 3) Representation of the non-material substance: Use contemporary artistic practices as examples to describe the various aspects of new media image in contemporary life. Discussions in this chapter of artistic creation is concentrated in the work of traditional media that use new media image as subject rather than works of new media art". At the end of the thesis, my artworks which relate to the topic are introduced for reference. / Detailed summary in vernacular field only. / 李天倫. / "2012年8月". / "2012 nian 8 yue". / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 77-79). / Abstract in Chinese and English. / Li Tianlun. / 引言 --- p.7 / Chapter 第一章 --- 影像的定義與科技發展的歷史脈絡 / Chapter 1.1 --- 當代生活的視覺經驗 --- p.8 / Chapter 1.2 --- 觀看與再現 --- p.9 / Chapter 1.3 --- 影像的意義構成 --- p.10 / Chapter 1.4 --- 數位影像的意義構成 --- p.11 / Chapter 1.5 --- 媒體與空間概念 --- p.15 / Chapter 1.6 --- 影像科技發展的歷史脈絡 --- p.17 / Chapter 第二章 --- 新媒體與數位影像 / Chapter 2.1 --- 新媒體的定義 --- p.23 / Chapter 2.2 --- 新媒體的特質 --- p.24 / Chapter 2.3 --- 觀看方式的轉變 --- p.28 / Chapter 2.4 --- 數位影像的複製、原真性與「靈光」 --- p.29 / Chapter 2.5 --- 虛擬與網絡－空間觀念的轉變 --- p.31 / Chapter 第三章 --- 非物質的物質化呈現－對應新媒體影像的藝術創作 / Chapter 3.1 --- 感知的回歸 --- p.34 / Chapter 3.2 --- 當代視覺語言的體現 --- p.37 / Chapter 3.3 --- 從無形到有形－資訊影像化 --- p.41 / Chapter 3.4 --- 網絡與影像流通 --- p.45 / Chapter 3.5 --- 數位影像與流行文化 --- p.49 / Chapter 3.6 --- 虛擬與真實的糾結 --- p.52 / 結語 --- p.55 / 附錄 / 我的作品 --- p.57 / 圖片來源 --- p.75 / 參考書目及資料 --- p.77

This thesis explores through the creation of four artworks, the nature of the sublime ruin. To facilitate this it examines the disintegration of selected religious feminine metaphors. The artworks are rendered through a multiplication of layers bound by translucent/transparent resin. These are produced to examine the potentials between traditional craft and contemporary digital mediums, thus creating sites where eroding fragments may express an excess of meaning through enigmatic construction.

Texte remanié de: Th. doct.--Histoire--Paris 4, 1991. / Bibliogr. p. 451-455.

Mémoire d'étude diplôme de conservateur des bibliothèques : Bibliothéconomie : Villeurbanne, ENSSIB : 2004.

Les images panoramiques sont des vues en largeur d'un espace physique. Ces larges images, en plus d'être intéressantes par leur aspect esthétique, sont un support essentiel pour de nombreuses applications comme par exemple l'orientation automatique d'un robot dans son environnement ou la création de cartes satellites. Pour obtenir un panorama, deux approches sont possibles : une approche matérielle et une approche logicielle. Dans l'approche logicielle, il y a deux problématiques : le recalage des images entre elles et le mélange des valeurs radiométriques des sections se recoupant. Ce mémoire s'intéresse à la problématique de mélange. En effet, les images à regrouper peuvent présenter des différences d'intensité pour diverses raisons. Il faut alors effectuer un mélange afin de faire disparaître ces différences et pouvoir ainsi produire un panorama sans transition visible. Plus précisément, nous travaillons sur l'amélioration de l'algorithme de construction panoramique par recalage à l'aide du flux optique présenté par Rebière et Toffa. Cette méthode de positionnement très efficace repose sur le recalage de chaque pixel, à l'aide du flux optique. Malheureusement l'algorithme de Rebière et Toffa ne gère pas les différences d'intensité qui peuvent exister entre les images. Dans ces conditions, les panoramas produits ne sont pas de qualité satisfaisante. Pour régler ce problème, nous intégrons donc la méthode de mélange multibande présentée par Brown et Lowe. Nous adaptons ainsi le mélange multibande à l'algorithme de recalage par flux optique afin de le rendre robuste aux différences d'intensité.

This thesis explores through the creation of four artworks, the nature of the sublime ruin. To facilitate this it examines the disintegration of selected religious feminine metaphors. The artworks are rendered through a multiplication of layers bound by translucent/transparent resin. These are produced to examine the potentials between traditional craft and contemporary digital mediums, thus creating sites where eroding fragments may express an excess of meaning through enigmatic construction.

Thesis (M.F.A.)--Rochester Institute of Technology, 1995. / Typescript. Includes bibliographical references (leaves 32-33).

Academisch proefschrift--Amsterdam, 1993.

CAFIMF--Ecole normale d'instituteurs--Paris, 1991.