Statistical cue integration in DAG deformable models

Deformable models are a useful modeling paradigm in computer vision. A deformable model is a curve, a surface, or a volume, whose shape, position, and orientation are controlled through a set of parameters. They can represent manufactured objects, human faces and skeletons, and even bodies of fluid. With low-level computer vision and image processing techniques, such as optical flow, we extract relevant information from images. Then, we use this information to change the parameters of the model iteratively until we find a good approximation of the object in the images. When we have multiple computer vision algorithms providing distinct sources of information (cues), we have to deal with the difficult problem of combining these, sometimes conflicting contributions in a sensible way. In this paper, we introduce the use of a directed acyclic graph (DAG) to describe the position and Jacobian of each point of deformable models. This representation is dynamic, flexible, and allows computational optimizations that would be difficult to do otherwise. We then describe a new method for statistical cue integration method for tracking deformable models that scales well with the dimension of the parameter space. We use affine forms and affine arithmetic to represent and propagate the cues and their regions of confidence. We show that we can apply the Lindeberg theorem to approximate each cue with a Gaussian distribution, and can use a maximum-likelihood estimator to integrate them. Finally, we demonstrate the technique at work in a 3D deformable face tracking system on monocular image sequences with thousands of frames.     

Ethephon and fosetyl residues in fruits from São Francisco Valley,Brazil

ABSTRACT

This survey describes the occurrence of Ethephon (ETH) and Fosetyl in fruits intended for export produced in the São Francisco Valley, Brazil. The determination of these compounds was carried out by the QuPPe-method (Quick Polar Pesticides Method), which was optimised and successfully validated according to the SANTE/11813/2017. From January 2016 to December 2018 a total of 1048 samples were analysed for ETH residues. In 547 (53%) of the samples, residues below the EU MRL of 1 mg kg^?1 were present. In 17 samples (2%) ETH residues were above 1 mg kg^?1. Overall, the mean ETH level decreased after 2016. Analyses of fosetyl showed that (18%) of 109 mango samples were positive for this compound. Phosphonic acid was found in concentrations ranging from 0.12 to 3.2 mg kg^?1 and 5% of the measurements were above the EU MRL of 2 mg kg^?1. The results emphasise the quality control of fruits produced in this region.     

3D Searchless Fractal Video Encoding at Low Bit Rates

The development of compression techniques is crucial for several applications that require efficient storage and transmission of large data volumes. Fractal theory has been used in image and video compression due to advantages such as resolution independence, high compression rate, fast decoding, among others. Fractal compression approaches explore the presence of self-similarity to remove data redundancy, allowing high compression while maintaining low quality degradation. Early fractal compression methods presented prohibitive encoding time related to the search for similar regions in the image or video. This work describes a low bit-rate 3D searchless fractal video encoder to perform fast compression with high visual fidelity. Experiments demonstrate that the results of the proposed approach are superior when compared to those obtained by state-of-the-art x264 video encoder at very low bit rates in high motion video sequences.     

Light scattering in polycrystalline alumina with bi-dimensionally large surface grains

Alumina ceramics with high in-line transmittance at 0.5–1.0 mm-thickness were prepared with different doping additives by sintering at 1850 °C in vacuum for 1–8 h. Depending on the additive contents and sintering variables bi-dimensionally large surface grains, caused by surface evaporation of MgO, had grown parallel to the surface with ～100 μm thickness and lateral sizes up to the millimeter range. The abnormal grain-growth process also resulted in the formation of pores entrapped inside the large surface grains within a narrow zone at 10–20 μm distance from the surface. The fraction of these pores is thickness-invariant. Scattering factors associated to the pores entrapped inside the bi-dimensionally large surface grains, second-phase particles, grain-boundaries, and microstructural surface defects are derived from the results of in-line transmission (at 600 nm) and are used together with microstructural characteristics to explain the light transmittance in these materials.     

Adaptive edge-preserving image denoising using wavelet transforms

Image denoising is a relevant issue found in diverse image processing and computer vision problems. It is a challenge to preserve important features, such as edges, corners and other sharp structures, during the denoising process. Wavelet transforms have been widely used for image denoising since they provide a suitable basis for separating noisy signal from the image signal. This paper describes a novel image denoising method based on wavelet transforms to preserve edges. The decomposition is performed by dividing the image into a set of blocks and transforming the data into the wavelet domain. An adaptive thresholding scheme based on edge strength is used to effectively reduce noise while preserving important features of the original image. Experimental results, compared to other approaches, demonstrate that the proposed method is suitable for different classes of images contaminated by Gaussian noise.     

A structural damage identification method based on genetic algorithm and vibrational data

The problem of damage identification in framed structures using vibrational data is considered. The identification problem is modelled as an optimization task and the use of measured natural frequencies as well as modeshape information in the construction of objective functions is discussed. In a first attempt, a standard genetic algorithm is shown to be ineffective in obtaining the correct damage distribution in test problems. Using domain knowledge, modifications are introduced in the coding process, in the initial population generation, in the fitness function, and in the genetic operators, leading to a promising tool to solve this class of problems. Synthetic problems, with the addition of noise in the simulated measured data associated with the damaged structure, are analysed in order to assess the capability of the proposed technique. Copyright © 2006 John Wiley & Sons, Ltd.     

Exploring heuristic and optimum branching algorithms for image phylogeny

Currently, multimedia objects can be easily created, stored, (re)-transmitted, and edited for good or bad. In this sense, there has been an increasing interest in finding the structure of temporal evolution within a set of documents and how documents are related to one another overtime. This process, also known in the literature as Multimedia Phylogeny, aims at finding the phylogeny tree(s) that best explains the creation process of a set of near-duplicate documents (e.g., images/videos) and their ancestry relationships. Solutions to this problem have direct applications in forensics, security, copyright enforcement, news tracking services and other areas. In this paper, we explore one heuristic and one optimum branching algorithm for reconstructing the evolutionary tree associated with a set of image documents. This can be useful for aiding experts to track the source of child pornography image broadcasting or the chain of image distribution in time, for instance. We compare the algorithms with the state-of-the-art solution considering 350,000 test cases and discuss advantages and disadvantages of each one in a real scenario.