Recovering spectral data from natural scenes with an RGB digital camera and colored filters

Many spectral‐recovery methods using RGB digital cameras assume the underlying smoothness of illuminant and reflectance spectra, and apply low‐dimensional linear models. The aim of the present work was to test whether a direct‐mapping method could be used instead of a linear‐models approach to recover spectral radiances and reflectances from natural scenes with an RGB digital camera and colored filters. In computer simulations, a conventional RGB digital camera with up to three colored filters was used to image scenes drawn from a hyperspectral image database. Three measures were used to evaluate recovery with the direct‐mapping method: goodness‐of‐fit, root‐mean‐square error, and a color‐difference metric. It was found that with two and three filters both spectral radiances and reflectances could be recovered sufficiently accurately for many practical applications. With little increase in computational complexity, an RGB camera and a few colored filters can provide significantly better recovery of natural scenes than an RGB camera alone. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 352–360, 2007     

Robust network monitoring in the presence of non-cooperative traffic queries

We present the design of a predictive load shedding scheme for a network monitoring platform that supports multiple and competing traffic queries. The proposed scheme can anticipate overload situations and minimize their impact on the accuracy of the traffic queries. The main novelty of our approach is that it considers queries as black boxes, with arbitrary (and highly variable) input traffic and processing cost. Our system only requires a high-level specification of the accuracy requirements of each query to guide the load shedding procedure and assures a fair allocation of computing resources to queries in a non-cooperative environment. We present an implementation of our load shedding scheme in an existing network monitoring system and evaluate it with a diverse set of traffic queries. Our results show that, with the load shedding mechanism in place, the monitoring system can preserve the accuracy of the queries within predefined error bounds even during extreme overload conditions.     

Computational color analysis of paintings for different artists of the XVI and XVII centuries

We have performed a computational color analysis of images of paintings for six master painters: Titian, Rubens, El Greco, Velázquez, Rembrandt, and Vermeer. These painters show the evolution from the renaissance to the baroque style. Different first and second‐order statistical parameters have been obtained and analyzed in order to fix which of them can be common for the different artists and which of them can be representative of a certain period of time or the evolution of the art. The firsts include the orientation and semi‐axes ratio of the ellipses that define the gamut in the chromaticity diagram and the dependencies with the frequency of the power of the Fourier transforms. Most differences among artists can be found in the volume and area of the gamut, the number of discernible colors which is greater for Titian, El Greco and Rubens, compared to Velázquez, Rembrandt and Vermeer, the average value of L* and the number of dark pixels.     

Effect of drying methods on the reactivity of chitosan towards Maillard reaction

The effect of drying methods on chitosan reactivity towards Maillard reaction during storage of dried chitosan–lactose systems was investigated. Two different structural forms of chitosan, scaffold and microspheres, were prepared. Then they were dried by lyophilization or using supercritical fluid technology (SF-CO₂) and stored with lactose under controlled temperature conditions (60 °C) and water activity (a_w = 0.65). The drying method produced slight modifications on the chitosan structure especially in samples submitted to SF-CO₂ treatment. Differences were more evident in the reactivity of chitosan–lactose systems during storage. Maillard reaction development was assessed by quantification of a new compound which originated from the acid hydrolysis of Amadori compounds (NFMD) resulting from chitosan–lactose interactions, and not detected in the acid hydrolysates of freshly prepared chitosan-lactose systems. Maillard reaction was influenced by different factors such as the manner of lactose addition, structure of chitosan (microspheres and scaffolds) and drying method. Lyophilized chitosan in the form of microspheres with lactose, presented the highest values of NFMD (428.45 mg/100 g of sample). The determination of this compound could be used as an index of the progress of Maillard reaction.     

Recognising safety critical events: Can automatic video processing improve naturalistic data analyses?

New trends in research on traffic accidents include Naturalistic Driving Studies (NDS). NDS are based on large scale data collection of driver, vehicle, and environment information in real world. NDS data sets have proven to be extremely valuable for the analysis of safety critical events such as crashes and near crashes. However, finding safety critical events in NDS data is often difficult and time consuming. Safety critical events are currently identified using kinematic triggers, for instance searching for deceleration below a certain threshold signifying harsh braking. Due to the low sensitivity and specificity of this filtering procedure, manual review of video data is currently necessary to decide whether the events identified by the triggers are actually safety critical. Such reviewing procedure is based on subjective decisions, is expensive and time consuming, and often tedious for the analysts. Furthermore, since NDS data is exponentially growing over time, this reviewing procedure may not be viable anymore in the very near future.     

Evolution of carbohydrate fraction in carbonated fermented milks as affected by beta-galactosidase activity of starter strains

The influence of carbonation on the evolution of lactose, galactose and glucose in fermented milks with added probiotic bacteria (Lactobacillus casei, Lactobacillus acidophilus and/or Bifidobacterium bifidum) was evaluated and related to beta-galactosidase activity of starter strains. During incubation and first days of refrigeration, lactose hydrolysis resulting in the liberation of galactose and glucose occurred in CT (Streptococcus thermophilus/Lb. casei), AT (Str. thermophilus/Lb. acidophilus) and ABT fermented milks (Str. thermophilus/Lb. acidophilus/Bifid. bifidum). Levels of galactose were higher than those of glucose and could be related to the preferential consumption of glucose by actively growing bacteria. Through the incubation, lactose and monosaccharide levels were not affected by milk carbonation. However, during refrigerated storage the presence of this gas was associated with slightly lower content of lactose and higher levels of galactose and glucose in AT and ABT products but not in CT fermented milks. Through the refrigeration galactose was moderately utilised by Lb. acidophilus in AT products whereas the presence of Bifid. bifidum seems to prevent the consumption of this sugar in ABT fermented milks. Glucose remained constant, with minor variations in CT products but a continuous increase of this sugar occurred in carbonated AT and ABT fermented milks during storage. Beta-galactosidase activity displayed by Str. thermophilus strains was similar at pH 6.5 (initial pH of non-carbonated samples) and pH 6.3 (initial pH of carbonated samples) whereas Lb. acidophilus LaA3 showed greater beta-galactosidase activity at pH 6.3 than at higher pH values. Thus, the enhanced metabolic activity of Lb. acidophilus caused by the low initial pH of carbonated milk also promoted higher cellular beta-galactosidase activity that could have released greater amounts of galactose and glucose from lactose in AT and ABT fermented milks through the refrigerated period. In CT fermented milks, similar beta-galactosidase activity levels of Str. thermophilus at pH 6.5 and 6.3 together with the absence of beta-galactosidase activity in Lb. casei could explain the lack of differences on glucose and galactose content between carbonated and non-carbonated samples.     

The design of a Virtual Library of Emblem Books

Antique documents, which undoubtedly represent our cultural heritage and can be considered a very rich source of information, are kept in many countries only on libraries with historical archives. The antiquity and fragility of such documents makes their access very restricted. Considering that nowadays the Internet is one of the most interesting places to publish any kind of information, it seems logical to use it to both preserve our cultural heritage and provide a broader access to these documents. This work presents a virtual library that stores data, transcribed texts and digitalized pages of historic Spanish documents from the 16th–18th centuries. This virtual library has two main objectives: first, by offering a set of services, including a powerful user interface to search and browse the documents, a bulletin board, a chat, or mail boxes, the virtual library is transformed into a meeting place for researchers that use emblem books as sources of information for their studies. Second, the virtual library contributes to the preservation of emblem books. We shall describe in this work the project that led to the development of the Virtual Library of Emblem Books, showing its evolution from the beginning (simple search forms and answer pages) to its current state as a virtual library, focusing on the techniques used to build an intuitive and powerful user interface. Copyright © 2006 John Wiley & Sons, Ltd.     

A general procedure to check conjunctive query containment

In this paper, we present a general procedure to test conjunctive query containment. We divide the containment problem into four categories, taking into account the underlying semantics (set or bag theoretic) and the presence or absence of built-in predicates in the queries. After a brief review of previous work on conjunctive query containment, we present a new procedure, called QCC (Query Containment Checker), which we show to be a general and uniform procedure to check the containment among conjunctive queries under the four categories mentioned above. We briefly describe the use of QCC to check bag containment of conjunctive queries, and explain in detail how to use QCC to check set containment of conjunctive queries with built-in predicates. In our conclusions, we point out some uses of QCC for other types of containment. Received: 21 January 2000 / 19 November 2001