Joaquín Fernández-Valdivia

Learn More
This paper analyzes how the natural scales of the shapes in 2D images can be extracted. Spatial information is analyzed by multiple units sensitive to both spatial and spatial-frequency variables. Scale estimates of the relevant shapes are constructed only from strongly responding detectors. The meaningful structures in the response of a detector (computed(More)
ÐThis paper describes a system for the automatically learned partitioning of ªvisual patternsº in 2D images, based on a sophisticated, band-pass, filtering operation with fixed scale and orientation sensitivity. In this scheme, the ªvisual patternsº are defined as the features which have the highest degree of alignment in the statistical structure across(More)
We present a number of autofocusing methods in lighting microscopy for its use in diatom identiica-tion. Among these, the Tenengrad method has been considered one of the best. The basic requirements for a practical autofocusing system are speed, sharpness and robustness to noise. Recently other focus measures based on a modiied Laplacian method are said to(More)
This paper introduces a new approach to solving the problem of representing planar curves. We describe the 2-D curve C not at all diierent scales , but each curve part C i of C, isolating a diierent structure at its single scale i. Therefore, we represent the planar curve at a scale vector (1 ; ; L) supposing that the curve is partitioned in L parts C 1 ; ;(More)
This paper introduces a new method for clustering data using a dynamic scheme. An appropriate partitioning is obtained based on both a dissimilarity measure between pairs of entities as well as a dynamic procedure of splitting. A dissimilarity function is deened by using the cost of the optimum path from a datum to each entity on a graph, with the cost of a(More)
ÐIt is of great benefit to have advance knowledge of human visual target acquisition performance for targets or other relevant objects. However, search performance inherently shows a large variance and depends strongly on prior knowledge of the perceived scene. A typical search experiment therefore requires a large number of observers to obtain(More)
In this paper we provide the reader with a visual representation of relationships among the impact of book chapters indexed in the Book Citation Index using information gain values and published by different academic publishers in specific disciplines. The impact of book chapters can be characterized statistically by citations histograms. For instance, we(More)
This paper presents a method for selecting proper scale parameters for edge detection. To this aim the image is preliminarily segmented into regions with a homogeneous intensity change model, by using a clustering algorithm based on a dissimilarity measure applied on feature vectors associated to the regions. The used algorithm is a standard clustering(More)
We introduce a novel methodology for mapping academic institutions based on their journal publication profiles. We consider that journals in which researchers from academic institutions publish their works can be considered as useful identifiers for representing the relationships between these institutions and establishing comparisons. But, when academic(More)
Here we study the relationship between journal quartile rankings of ISI impact factor (at the 2010) and journal classification in four impact classes, i.e., highest impact, medium highest impact, medium lowest impact, and lowest impact journals in subject category computer science artificial intelligence. To this aim, we use fuzzy maximum likelihood(More)