Impact of object extraction methods on classification performance in surface inspection systems

In surface inspection applications, the main goal is to detect all areas which might contain defects or unacceptable imperfections, and to classify either every single 'suspicious' region or the investigated part as a whole. After an image is acquired by the machine vision hardware, all pixels that deviate from a pre-defined 'ideal' master image are set to a non-zero value, depending on the magnitude of deviation. This procedure leads to so-called "contrast images", in which accumulations of bright pixels may appear, representing potentially defective areas. In this paper, various methods are presented for grouping these bright pixels together into meaningful objects, ranging from classical image processing techniques to machine-learning-based clustering approaches. One important issue here is to find reasonable groupings even for non-connected and widespread objects. In general, these objects correspond either to real faults or to pseudo-errors that do not affect the surface quality at all. The impact of different extraction methods on the accuracy of image classifiers will be studied. The classifiers are trained with feature vectors calculated for the extracted objects found in images labeled by the user and showing surfaces of production items. In our investigation artificially created contrast images will be considered as well as real ones recorded on-line at a CD imprint production and at an egg inspection system. © Springer-Verlag 2009

Procedimiento de preparación de materiales superconductores texturados obtenidos por fusión zonal inducida por láser

Fecha de solicitud: 01.09.2000.- Consejo Superior de Investigaciones Científicas (CSIC).- Universidad de Zaragoza.[EN]Procedure for preparing textured superconductor materials obtained by laser-induced zone melting.Materials of the YBCO, Bi-2212 and Bi-2223 families are obtained from a ceramic using a laser zone melting system, including: a watertight growth chamber in which two mechanical extensions are housed to support the system for shaft transfer and rotation movement; two separate windows, made of quartz and of zinc selenide, which provide passage for the two lasers connected to the chamber, one Nd:YAG and the other CO2. Each laser focuses on the preform with two or more different shapes. The preforms are fastened to the shafts with various types of very small, commercially available clamps. These materials, given their textured microstructure, are useful in application such as power supply busbars, current limiter components, network filters, etc. [ES] Procedimiento de preparación de materiales superconductores texturados obtenidos por fusión zonal inducida por láser. Se obtienen materiales de las familias YBCO, Bi-2212 y Bi-2223, a partir de una cerámica y mediante un sistema de fusión zonal por láser, que incluye: una cámara de crecimiento estanca, donde se encuentran alojadas dos extensiones mecánicas que hacen de soporte del sistema de movimiento de traslación y rotación de ejes; dos ventanas distintas, de cuarzo y de seleniuro de cinc, que permiten el paso de dos láseres acoplados a la cámara, uno de Nd:YAG y otro de CO2. Cada láser se enfoca sobre la preforma de dos o más formas distintas. las preformas se sujetan sobre los ejes con diversos tipos de mordazas comerciales de tamaño muy reducido. estos materiales por su microestructura texturada les hace útiles en aplicaciones como barras de alimentación, componentes para limitadores de corriente, filtros de red, etc.Peer reviewe