Advanced optical correlation and digital methods for pattern matching—50th anniversary of Vander Lugt matched filter

Abstract

On the verge of the 50th anniversary of Vander Lugt's formulation for pattern matching based on matched filtering and optical correlation, we acknowledge the very intense research activity developed in the field of correlation-based pattern recognition during this period of time. The paper reviews some domains that appeared as emerging fields in the last years of the 20th century and have been developed later on in the 21st century. Such is the case of three-dimensional (3D) object recognition, biometric pattern matching, optical security and hybrid optical-digital processors. 3D object recognition is a challenging case of multidimensional image recognition because of its implications in the recognition of real-world objects independent of their perspective. Biometric recognition is essentially pattern recognition for which the personal identification is based on the authentication of a specific physiological characteristic possessed by the subject (e.g. fingerprint, face, iris, retina, and multifactor combinations). Biometric recognition often appears combined with encryption-decryption processes to secure information. The optical implementations of correlation-based pattern recognition processes still rely on the 4f-correlator, the joint transform correlator, or some of their variants. But the many applications developed in the field have been pushing the systems for a continuous improvement of their architectures and algorithms, thus leading towards merged optical-digital solutions.

Encriptación de información mediante procesamiento óptico

“…Más tarde, en lo que constituyó un trabajo pionero, se propuso un método de encriptación de datos usando una arquitectura óptica 4f y dos máscaras aleatorias de fase (Refregier & Javidi, 1995). Dicha arquitectura se había usado hasta ese momento para el procesamiento óptico de información, particularmente para correlacionar dos funciones (Goodman, 1996;Vander-Lugt, 1964), con el fin de detectar, localizar e identificar la presencia de un objeto de interés (Millán, 2012), pero en el contexto de la encriptación óptica el objetivo es la protección de la información. En este método de encriptación (Refregier & Javidi, 1995) una de las máscaras se ubica en el plano de entrada, en contacto con el dato que se desea proteger, en tanto que la segunda máscara se ubica en el primer plano de Fourier del sistema 4f.…”

Holographic photonic neuron

“…There has been significant work on optical implementations of machine vision systems based on the Vander Lugt optical correlator [15,16]. The correlator epitomizes classical optical computing that measures the similarity between two patterns.…”

Optical image encryption using gamma distribution phase masks in the gyrator domain

“…Optical information encryption technology has received extensive attention from researchers in recent years because of its advantages of parallel and high-speed processing capability, as well as the controllability of phase components. One of the earliest and most widely studied optical encryption method for image encryption was the double random phase encoding (DRPE) system which was proposed by Refregier and Javidi [1][2][3][4][5]. This architecture is based on a 4-f imaging system and together with a pair of independent random phase keys (PRKs), which one in the input plane and another in the Fourier plane for encryption amplitude image.…”