1. University of Extremadura,Department of Graphic Expression,Cáceres,Spain
2. Complutense University,Department of Computer Architecture,Madrid,Spain
3. Computer Graphics and Data Engineering Group (COGRADE), Centro Singular de Investigación en Tecnoloxías Intelixentes (CITIUS), University of Santiago de Compostela,Spain
4. University of Extremadura,Department of Technology of Computers and Communications,Spain