Avoiding staff removal stage in optical music recognition: application to scores written in white mensural notation

Staff detection and removal is one of the most important issues in optical music recognition (OMR) tasks since common approaches for symbol detection and classification are based on this process. Due to its complexity, staff detection and removal is often inaccurate, leading to a great number of errors in posterior stages. For this reason, a new approach that avoids this stage is proposed in this paper, which is expected to overcome these drawbacks. Our approach is put into practice in a case of study focused on scores written in white mensural notation. Symbol detection is performed by using the vertical projection of the staves. The cross-correlation operator for template matching is used at the classification stage. The goodness of our proposal is shown in an experiment in which our proposal attains an extraction rate of 96 % and a classification rate of 92 %, on average. The results found have reinforced the idea of pursuing a new research line in OMR systems without the need of the removal of staff lines.

A competition-based deformable template for junction extraction

Comunicación presentada en el VIII Simposium Nacional de Reconocimiento de Formas y Análisis de Imágenes, Bilbao, mayo 1999.

Topological SLAM using a graph-matching based method on omnidirectional images

Comunicación presentada en el XI Workshop of Physical Agents, Valencia, 9-10 septiembre 2010.

Contextual visual localization: cascaded submap classification, optimized saliency detection, and fast view matching

In this paper, we present a novel coarse-to-fine visual localization approach: contextual visual localization. This approach relies on three elements: (i) a minimal-complexity classifier for performing fast coarse localization (submap classification); (ii) an optimized saliency detector which exploits the visual statistics of the submap; and (iii) a fast view-matching algorithm which filters initial matchings with a structural criterion. The latter algorithm yields fine localization. Our experiments show that these elements have been successfully integrated for solving the global localization problem. Context, that is, the awareness of being in a particular submap, is defined by a supervised classifier tuned for a minimal set of features. Visual context is exploited both for tuning (optimizing) the saliency detection process, and to select potential matching views in the visual database, close enough to the query view.

Design of online practical lessons in colorimetry

Applied colorimetry is an important module in the program of the elective subject "Colour Science: industrial applications”. This course is taught in the Optics and Optometry Degree and it has been used as a testing for the application of new teaching and assessment techniques consistent with the new European Higher Education Area. In particular, the main objective was to reduce the attendance to lessons and encourage the individual and collective work of students. The reason for this approach is based on the idea that students are able to work at their own learning pace. Within this dynamic work, we propose online lab practice based on Excel templates that our research group has developed ad-hoc for different aspects of colorimetry, such as conversion to different colour spaces, calculation of perceptual descriptors (hue, saturation, lightness), calculation of colour differences, colour matching dyes, etc. The practice presented in this paper is focused on the learning of colour differences. The session is based on a specific Excel template to compute the colour differences and to plot different graphs with these colour differences defined at different colour spaces: CIE ΔE, CIE ΔE94 and the CIELAB colour space. This template is implemented on a website what works by addressing the student work at a proper and organized way. The aim was to unify all the student work from a website, therefore the student is able to learn in an autonomous and sequential way and in his own pace. To achieve this purpose, all the tools, links and documents are collected for each different proposed activity to achieve guided specific objectives. In the context of educational innovation, this type of website is normally called WebQuest. The design of a WebQuest is established according to the criteria of usability and simplicity. There are great advantages of using WebQuests versus the toolbox “Campus Virtual” available in the University of Alicante. The Campus Virtual is an unfriendly environment for this specific purpose as the activities are organized in different sectors depending on whether the activity is a discussion, an activity, a self-assessment or the download of materials. With this separation, it is more difficult that the student follows an organized sequence. However, our WebQuest provides a more intuitive graphical environment, and besides, all the tasks and resources needed to complete them are grouped and organized according to a linear sequence. In this way, the student guided learning is optimized. Furthermore, with this simplification, the student focuses on learning and not to waste resources. Finally, this tool has a wide set of potential applications: online courses of colorimetry applied for postgraduate students, Open Course Ware, etc.

NGC 7419 as a template for red supergiant clusters

Context. The open cluster NGC 7419 is known to contain five red supergiants and a very high number of Be stars. However, there are conflicting reports about its age and distance that prevent a useful comparison with other clusters. Aims. We intend to obtain more accurate parameters for NGC 7419, using techniques different from those of previous authors, so that it may be used as a calibrator for more obscured clusters. Methods. We obtained Strömgren photometry of the open cluster NGC 7419, as well as classification spectroscopy of ~20 stars in the area. We then applied standard analysis and classification techniques. Results. We find a distance of 4 ± 0.4 kpc and an age of 14 ± 2 Myr for NGC 7419. The main-sequence turn-off is found at spectral type B1, in excellent agreement. We identify 179 B-type members, implying that there are more than 1200 M⊙ in B stars at present. Extrapolating this to lower masses indicates an initial cluster mass of between 7000 and 10 000 M⊙, depending on the shape of the initial mass function. We find a very high fraction (≈40%) of Be stars around the turn-off, but very few Be stars at lower masses. We also report for the first time a strong variability in the emission characteristics of Be stars. We verified that the parameters of the red supergiant members can be used to obtain accurate cluster parameters. Conclusions. NGC 7419 is sufficiently massive to serve as a testbed for theoretical predictions and as a template to compare more obscured clusters. The distribution of stars above the main-sequence turn-off is difficult to accommodate with current evolutionary tracks. Though the presence of five red supergiants is marginally consistent with theoretical expectations, the high number of Be stars and very low number of luminous evolved B stars hint at some unknown physical factor that is not considered in current synthesis models.