Уровневая модель данных маркетинговых исследований, ориентированная на поиск закономерностей в результатах опросов

В работе предложена модель данных маркетинговых исследований, позволяющая существенно упростить процесс проектирования опросных листов, ввод данных и их анализ.The work offers a model of marketing research data that allows to simplify substantially the processes of questionnaire designing, data input and analysis

Эффект двойного квантования и его особенности

В работе получены достаточные условия проявления и отсутствия проявления эффекта двойного квантования, возникающего при двукратной JPEG-компрессии цифрового изображения, что может быть использовано для создания практического метода доказательства подлинности цифровой фотографии.In this work there have been received sufficient conditions of displaying or absence of displaying of double quantization effect, that arise at double JPEG-compression of digital image, that can be used in creation of practical method of provement authenticity of digital photograph

La informática forense y sus analogías: la balística digital

Con el progreso de las tecnologías de la información sobre múltiples aspectos de la vida diaria, se hace cada vez más común la presencia de evidencia digital en las investigaciones judiciales. La evidencia, en cuanto contenedor físico de datos con valor investigativo, presenta distintos grados de complejidad, y la evidencia digital es un exponente excepcional en este aspecto. Algunas preguntas poco frecuentes en cuanto a la evidencia digital, y muy difíciles de responder son ¿”Quién” o “Qué” creó esta evidencia? ¿La evidencia, fue modificada, editada o manipulada de alguna manera? Para responder a estas preguntas, es necesaria la aplicación de técnicas de “balística digital”, una rama poco explorada de la informática forense en nuestro país

Review on passive approaches for detecting image tampering

This paper defines the presently used methods and approaches in the domain of digital image forgery detection. A survey of a recent study is explored including an examination of the current techniques and passive approaches in detecting image tampering. This area of research is relatively new and only a few sources exist that directly relate to the detection of image forgeries. Passive, or blind, approaches for detecting image tampering are regarded as a new direction of research. In recent years, there has been significant work performed in this highly active area of research. Passive approaches do not depend on hidden data to detect image forgeries, but only utilize the statistics and/or content of the image in question to verify its genuineness. The specific types of forgery detection techniques are discussed below

Detecting Image Brush Editing Using the Discarded Coefficients and Intentions

This paper describes a quick and simple method to detect brush editing in JPEG images. The novelty of the proposed method is based on detecting the discarded coefficients during the quantization of the image. Another novelty of this paper is the development of a subjective metric named intentions. The method directly analyzes the allegedly tampered image and generates a forgery mask indicating forgery evidence for each image block. The experiments show that our method works especially well in detecting brush strokes, and it works reasonably well with added captions and image splicing. However, the method is less effective detecting copy-moved and blurred regions. This means that our method can effectively contribute to implementing a complete imagetampering detection tool. The editing operations for which our method is less effective can be complemented with methods more adequate to detect them

Digital Video Inpainting Detection Using Correlation Of Hessian Matrix

The use of digital video during forensic investigation helps in providing evidence related to crime scene. However, due to freely available user friendly video editing tools, the forgery of acquired digital videos that are used as evidence in a law suit is now simpler and faster. As a result, it has become easier for manipulators to alter the contents of digital evidence. For instance, inpainting technique is used to remove an object from a video without leaving any artefact of illegal tampering. Therefore, this paper presents a technique for detecting and locating inpainting forgery in a video sequence with static camera motion. Our technique exploits statistical correlation of Hessian matrix (SCHM) to detect and locate tampered regions within a video sequence. The results of our experiments prove that the technique effectively detect and locate areas which are tampered using both texture and structure based inpainting with an average precision rate of 99.79% and an average false positive rate of 0.29%

Abordagem passiva para reconhecimento de adulterações em imagens digitais através da análise do padrão CFA e do BAG

A criação e a comercialização de softwares de edição de imagens permitiu que pessoas comuns pudessem realizar qualquer tipo de manipulação em imagens digitais. Em um cenário judicial, em que autenticidade e integridade dos dados são cruciais, se faz necessário técnicas que permitam garantir tais atributos. A análise forense em imagens digitais busca, através de métodos computacionais científicos, reconhecer a presença ou ausência desses atributos. O presente trabalho apresenta um método de reconhecimento de adulteração em imagens com e sem compressão JPEG. Esse método baseia-se em técnicas de análise de inconsistência do BAG (Block Artifact Grid) e do Padrão CFA (Color Filter Array) da imagem que é gerada a partir de técnicas de adulteração, tais como composição e clonagem. Os testes foram realizados em 960 imagens, utilizando as taxas de acurácia, sensibilidade, especificidade e precisão como métricas para a avaliação da efetividade do método

Double-Compressed JPEG Detection in a Steganalysis System

The detection of hidden messages in JPEG images is a growing concern. Current detection of JPEG stego images must include detection of double compression: a JPEG image is double compressed if it has been compressed with one quality factor, uncompressed, and then re-compressed with a different quality factor. When detection of double compression is not included, erroneous detection rates are very high. The main contribution of this paper is to present an efficient double-compression detection algorithm that has relatively lower dimensionality of features and relatively lower computational time for the detection part, than current comparative classifiers. We use a model-based approach for creating features, using a subclass of Markov random fields called partially ordered Markov models (POMMs) to modeling the phenomenon of the bit changes that occur in an image after an application of steganography. We model as noise the embedding process, and create features to capture this noise characteristic. We show that the nonparametric conditional probabilities that are modeled using a POMM can work very well to distinguish between an image that has been double compressed and one that has not, with lower overall computational cost. After double compression detection, we analyze histogram patterns that identify the primary quality compression factor to classify the image as stego or cover. The latter is an analytic approach that requires no classifier training. We compare our results with another state-of-the-art double compression detector. Keywords: steganalysis; steganography; JPEG; double compression; digital image forensics

Re-compression Based JPEG Forgery Detection and Localization with Optimal Reconstruction

In today’s media–saturated society, digital images act as the primary carrier for majority of information that flows around us. However, because of the advent of highly sophisticated easy–to–use image processing tools, modifying images has become easy. Joint Photographic Experts Group (JPEG) is the most widely used format, prevalent today as a world–wide standard, for compression and storage of digital images. Almost all present–day digital cameras use the JPEG format for image acquisition and storage, due to its efficient compression features and optimal space requirement. In this propose work we aim to detect malicious tampering of JPEG images, and subsequently reconstruct the forged image optimally. We deal with lossy JPEG image format in this paper, which is more widely adopted compared to its lossless counter–part. The proposed technique is capable of detecting single as well as multiple forged regions in a JPEG image. We aim to achieve optimal reconstruction since the widely used JPEG being a lossy technique, under no condition would allow 100% reconstruction. The proposed reconstruction is optimal in the sense that we aim to obtain a form of the image, as close to its original form as possible, apart from eliminating the effects of forgery from the image. In this work, we exploit the inherent characteristics of JPEG compression and re–compression, for forgery detection and reconstruction of JPEG images. To prove the efficiency of our proposed technique we compare it with the other JPEG forensic techniques and using quality metric measures we assess the visual quality of the reconstructed image