Search results for " pattern"
showing 10 items of 2245 documents
Perceptual similarity between color images using fuzzy metrics
2016
A method to measure the similarity between color images is proposed.Correlation among the color image channels is taken into account.Proposed similarity measure is based on fuzzy metrics because of their advantages.The proposal matches well with the perceptual visual similarity between color images. In many applications of the computer vision field measuring the similarity between (color) images is of paramount importance. However, the commonly used pixelwise similarity measures such as Mean Absolute Error, Peak Signal to Noise Ratio, Mean Squared Error or Normalized Color Difference do not match well with perceptual similarity. Recently, it has been proposed a method for gray-scale image s…
Colour image segmentation and labeling through multiedit-condensing
1992
Abstract A new method is proposed for detecting and locating objects of interest within a colour scene under very strong variabilities in lighting conditions, object shape and pigmentation. The method is based on Nearest Neighbour classification and Multiedit-Condensing techniques and is applied to implement the vision subsystem of a robotic citric harvesting device. Experiments and results are reported showing the effectiveness of the method and illustrating its appropriateness to the proposed task.
Prototype selection for the nearest neighbour rule through proximity graphs
1997
Abstract In this paper, the Gabriel and Relative Neighbourhood graphs are used to select a suitable subset of prototypes for the Nearest Neighbour rule. Experiments and results are reported showing the effectiveness of the method and comparing its performance to those obtained by classical techniques.
Irredundant tandem motifs
2014
Eliminating the possible redundancy from a set of candidate motifs occurring in an input string is fundamental in many applications. The existing techniques proposed to extract irredundant motifs are not suitable when the motifs to search for are structured, i.e., they are made of two (or several) subwords that co-occur in a text string s of length n. The main effort of this work is studying and characterizing a compact class of tandem motifs, that is, pairs of substrings {m1, m2} occurring in tandem within a maximum distance of d symbols in s, where d is an integer constant given in input. To this aim, we first introduce the concept of maximality, related to four specific conditions that h…
Right-Justified Characterization for Generating Regular Pattern Avoiding Permutations
2017
ECO-method and its corresponding succession rules allow to recursively define and construct combinatorial objects. The induced generating trees can be coded by corresponding pattern avoiding permutations. We refine succession rules by using succession functions in case when avoided patterns are regular or c-regular. Although regular patterns are hard to be recognized in general, we give a characterization for its right-justified property which is a prerequisite in the definition of the regular pattern. Based on this characterization, we show the (c-)regularity for various classes of permutations avoiding sets of patterns with variable lengths. Last, the technique of succession functions per…
XPL the Extensible Presentation Language
2009
The last decade has witnessed a growing interest in the development of web interfaces enabling both multiple ways to access contents and, at the same time, fruition by multiple modalities of interaction (point-and-click, contents reading, voice commands, gestures, etc.). In this paper we describe a framework aimed at streamlining the design process of multi-channel, multimodal interfaces enabling full reuse of software components. This framework is called the eXtensible Presentation architecture and Language (XPL), a presentation language based on design pattern paradigm that keeps separated the presentation layer from the underlying programming logic. The language supplies a methodology to…
Lesion of areas 17/18/19: effects on the cat's performance in a binary detection task
1988
The ability of two cats to discriminate between two geometrical outline patterns in the presence of superimposed Gaussian visual noise — i.e. in a binary detection task — was tested before and after bilateral removal of cortical areas 17, 18 and 19. The detection probability PD was measured as a function of the signal-to-noise ratio. After a lesion of areas 17, 18 and 19 both cats were unable to carry out the discrimination tasks. Their detection performance dropped to chance level, but after an extensive phase of retraining (3 months) they regained the ability to discriminate visual patterns. It was thus possible to obtain detection curves and to determine a measure of a performance which …
Recognition of familiarity on the basis of howls: a playback experiment in a captive group of wolves
2015
Playback experiments were conducted with a pack of captive Iberian wolves. We used a habituation–discrimination paradigm to test wolves’ ability to discriminate howls based on: (1) artificial manipulation of acoustic parameters of howls and (2) the identity of howling individuals. Manipulations in fundamental frequency and frequency modulation within the natural range of intra-individual howl variation did not elicit dishabituation, while manipulation of modulation pattern did produce dishabituation. With respect to identity, across trials wolves habituated to unfamiliar howls by a familiar wolf (i.e., no direct contact, but previous exposure to howls by this wolf), but not to unfamiliar ho…
Dynamics of two competing species in the presence of Lévy noise sources
2010
We consider a Lotka-Volterra system of two competing species subject to multiplicative alpha-stable Lévy noise. The interaction parameter between the species is a random process which obeys a stochastic differential equation with a generalized bistable potential in the presence both of a periodic driving term and an additive alpha-stable Lévy noise. We study the species dynamics, which is characterized by two different regimes, exclusion of one species and coexistence of both. We find quasi-periodic oscillations and stochastic resonance phenomenon in the dynamics of the competing species, analysing the role of the Lévy noise sources.
Counting by Statistics on Search Trees: Application to Constraint Satisfaction Problems
1997
In 1975, Knuth proposed a simple statistical method for investigating search trees. We use this technique for estimating the number of solutions of constraint satisfaction problem CSP and boolean satisfiability problem SAT instances. We show that, depending on domain reductions, tree-based estimates have a lower variance than estimates based on uniform sampling from the search space. Nevertheless, because the variance remains extremely high in the general case, a confidence interval cannot be derived, but a lower bound of the number of solutions. These results are confirmed by many experiments.