60 research outputs found
An Evaluation of Popular Copy-Move Forgery Detection Approaches
A copy-move forgery is created by copying and pasting content within the same
image, and potentially post-processing it. In recent years, the detection of
copy-move forgeries has become one of the most actively researched topics in
blind image forensics. A considerable number of different algorithms have been
proposed focusing on different types of postprocessed copies. In this paper, we
aim to answer which copy-move forgery detection algorithms and processing steps
(e.g., matching, filtering, outlier detection, affine transformation
estimation) perform best in various postprocessing scenarios. The focus of our
analysis is to evaluate the performance of previously proposed feature sets. We
achieve this by casting existing algorithms in a common pipeline. In this
paper, we examined the 15 most prominent feature sets. We analyzed the
detection performance on a per-image basis and on a per-pixel basis. We created
a challenging real-world copy-move dataset, and a software framework for
systematic image manipulation. Experiments show, that the keypoint-based
features SIFT and SURF, as well as the block-based DCT, DWT, KPCA, PCA and
Zernike features perform very well. These feature sets exhibit the best
robustness against various noise sources and downsampling, while reliably
identifying the copied regions.Comment: Main paper: 14 pages, supplemental material: 12 pages, main paper
appeared in IEEE Transaction on Information Forensics and Securit
Automatic Dating of Historical Documents
With the growing number of digitized documents available to researchers it is becoming possible to answer scientific questions by simply analyzing the image content. In this article, a new approach for the automatic dating of historical documents is proposed. It is based on an approach only recently proposed for scribe identification. It uses local RootSIFT descriptors which are encoded using VLAD. The method is evaluated using a dataset consisting of context areas of medieval papal charters covering around 150 years from 1049 to 1198 AD. Experimental results show very promising mean absolute errors of about 17 years
Towards Arbitrary Noise Augmentation - Deep Learning for Sampling from Arbitrary Probability Distributions
Accurate noise modelling is important for training of deep learning
reconstruction algorithms. While noise models are well known for traditional
imaging techniques, the noise distribution of a novel sensor may be difficult
to determine a priori. Therefore, we propose learning arbitrary noise
distributions. To do so, this paper proposes a fully connected neural network
model to map samples from a uniform distribution to samples of any explicitly
known probability density function. During the training, the Jensen-Shannon
divergence between the distribution of the model's output and the target
distribution is minimized. We experimentally demonstrate that our model
converges towards the desired state. It provides an alternative to existing
sampling methods such as inversion sampling, rejection sampling, Gaussian
mixture models and Markov-Chain-Monte-Carlo. Our model has high sampling
efficiency and is easily applied to any probability distribution, without the
need of further analytical or numerical calculations
Recognizing Characters in Art History Using Deep Learning
In the field of Art History, images of artworks and their contexts are core
to understanding the underlying semantic information. However, the highly
complex and sophisticated representation of these artworks makes it difficult,
even for the experts, to analyze the scene. From the computer vision
perspective, the task of analyzing such artworks can be divided into
sub-problems by taking a bottom-up approach. In this paper, we focus on the
problem of recognizing the characters in Art History. From the iconography of
(Figure 1), we consider the representation of
the main protagonists, and , across different artworks and
styles. We investigate and present the findings of training a character
classifier on features extracted from their face images. The limitations of
this method, and the inherent ambiguity in the representation of ,
motivated us to consider their bodies (a bigger context) to analyze in order to
recognize the characters. Convolutional Neural Networks (CNN) trained on the
bodies of and are able to learn person related features and
ultimately improve the performance of character recognition. We introduce a new
technique that generates more data with similar styles, effectively creating
data in the similar domain. We present experiments and analysis on three
different models and show that the model trained on domain related data gives
the best performance for recognizing character. Additionally, we analyze the
localized image regions for the network predictions. Code is open-sourced and
available at
https://github.com/prathmeshrmadhu/recognize_characters_art_history and the
link to the published peer-reviewed article is
https://dl.acm.org/citation.cfm?id=3357242
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