In the current era of communications and information technologies, automatic biometric personal recognition systems represent the state of the art in high-performance signal- and image-processing applications. In fact, it is not difficult to find in our daily lives systems requesting our personal authentication/identification before allowing us to use them; electronic tellers, computers, mobile phones and even cars require such authorization. Many end-user applications that demand better levels of security than PINs, passwords or ID cards use personal recognition algorithms based on biometric (physiological or behavioral) characteristics, usually delivering them as a kernel.