Papers by Francisco Hernandez
Pattern Recognition, 2006
The main goal of this work is to compare pyramidal structures proposed to solve segmentation task... more The main goal of this work is to compare pyramidal structures proposed to solve segmentation tasks. Segmentation algorithms based on regular and irregular pyramids are described, together with the data structures and decimation procedures which encode and manage the information in the pyramid. In order to compare the different segmentation algorithms, we have employed three types of quality measurements: the shift variance measure, the F function and the Q function.
Pattern Recognition, 2002
This paper presents a non-parametric method to extract a very short feature vector from the curva... more This paper presents a non-parametric method to extract a very short feature vector from the curvature function of a planar shape. Curvature is adaptively calculated using a new procedure that removes noise from the contour without missing relevant points. Then, its Fourier transform is projected onto a set of vectors, which have been chosen to be as representative as possible, to obtain the similarity between the input object and each vector of the set. These similarity values are the elements of the feature vector. The proposed method is very fast and classi"cation has proven that the representation is good.
Pattern Recognition, 2004
This paper presents a new segmentation technique for color images. It relies on building an irreg... more This paper presents a new segmentation technique for color images. It relies on building an irregular pyramid into a regular one, presenting only nodes associated to homogeneous color regions. Hence, the size of the irregular pyramid is bounded. Segmentation is performed by rearranging the set of links among pyramid nodes. Unlike other hierarchical methods based on relinking procedures, our algorithm does not operate in an iterative way and it preserves region connectivity.
Fresenius Journal of Analytical Chemistry, 1993
An analytical study on the determination of boron in environmental water samples was carried out.... more An analytical study on the determination of boron in environmental water samples was carried out. The curcumin and carmine standard methods were compared with the most recent Azomethine-H method in order to evaluate their analytical characteristics and feasibility for the analysis of boron in water samples. Analyses of synthetic water, ground water, sea water and waste water samples were carried out and a statistical evaluation of the results was made. The Azomethine-H method was found to be the most sensitive (detection limit 0.02 mg 1−1) and selective (no interference of commonly occurring ions in water was observed), showing also the best precision (relative standard deviation lower than 4%). Moreover, it gave good results for all types of samples analyzed. The accuracy of this method was tested by the addition of known amounts of standard solutions to different types of water samples. The slopes of standard additions and direct calibration graphs were similar and recoveries of added boron ranged from 99 to 107%.
Hablar del Renacimiento implica entrar en complicadas disquisiciones sobre el carácter de éste mo... more Hablar del Renacimiento implica entrar en complicadas disquisiciones sobre el carácter de éste momento histórico y su relación con la Edad Media y con la Modernidad.
Uploads
Papers by Francisco Hernandez