K. Styczynski

Bio: K. Styczynski is an academic researcher from University of Warsaw. The author has contributed to research in topics: Optical correlator & Filter (video). The author has an hindex of 4, co-authored 8 publications receiving 69 citations.

Dual nonlinear correlator based on computer controlled joint transform processor: Digital analysis and optical results

Abstract: The hybrid optoelectronic processor, presented in this paper, realizes the dual nonlinear correlation (DNC) in a set-up based on a two-step nonlinear joint transform correlator architecture. In the first step three power spectrum distributions (input scene power spectrum, reference target power spectrum, and the joint power spectrum) necessary for the nonlinear processing are captured with a CCD camera. Nonlinear modification of the joint power spectrum, which does not have to be symmetrical in the input and reference channels, is introduced digitally. In the second step, the modified joint power spectrum is Fourier transformed optically. Numerical analysis of this processor shows a crucial influence of the dynamic range and the limited number of grey levels of the CCD camera during image acquisition in the first step, on the output signal parameters and the discrimination capability of the set-up. Optical results of recognition obtained for noise-free segmented input scenes show that the set-up ...

Computer-generated binary phase-only filters with enhanced light efficiency recorded in silver halide sensitized gelatin

Abstract: The silver halide sensitized gelatin (SHSG) technique of bleaching is proposed for producing computer-generated binary phase-only filters. A comparison of light efficiency and recognition results for amplitude- and phase-recorded filters is presented.

Amplitude-encoded phase-only filters for pattern recognition: influence of the bleaching procedure

Abstract: The main techniques for optical pattern recognition are based on the correlation methods. In the past few years several correlation filters related to classical matched spatial filters have been proposed1'2 and different measures of performances have been introduced3. Recent works have shown that the problem of low light efficiency of optical correlators can be avided with the help of several types of pure phase-only filters . They have also good features for recognition process such as high discrimination capability and high sharp correlation peaks. Optical realization of the phase-only5flters (POF) based on holographic recording method is very difficult ' . Using digital methods one cn easily codify and modify the filter depending on the applications. The binary encoding of the phase-only filter (or its binary version) is the best candidate for recent applications in pattern recognition. Nevertheless most of graphic devices controlled by computer such as plotter, laser printer or the majority of spatial light modulators can only modulate the amplitude. For such a reason several methods have been recenly proposed to obtain amplitude encoded phase-only filters (AEPOF) , which can be written on an amplitude modulating device. However, amplitude modulation does not provide high light efficiency of the optical correlator. The use of phase materials for spatial filters recording allows better utilization of laser light in recognition systems and keeps laser power requirements lower. One of the more popular conventional phase materials is the bleached holographic emulsion. Bleaching removes the attenuation giving more light in the output correlation plane, but also in the case of classical matched filtering distortion and increased scattering noise occur in the reconstructed avefront which degrades the recognition capability of the filter . Binary amplitude encoded computer generated holograms do not suffer from distortion after bleaching11, because in this case the distribution of the phase hologram is identical to the distribution of the amplitude hologram without bias. The reconstruction is not more disturbed than the reconstruction of the amplitude hologram. In this paper we analyze the usefulness for pattern recognition of the bleached mplitude encoded phase-only filters based on Burckhardt's method . The silver halide (sensitized) gelatine (SHSG)12 is proposed to record computer generated phase-'only filter. The SHSG provides higher signal to noise ratio (SNR) that conventionally bleached eiitulsions because of absence of scattering centers after processing.

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.

Improved decryption quality and security of a joint transform correlator-based encryption system

Abstract: Some image encryption systems based on modified double random phase encoding and joint transform correlator architecture produce low quality decrypted images and are vulnerable to a variety of attacks. In this work, we analyse the algorithm of some reported methods that optically implement the double random phase encryption in a joint transform correlator. We show that it is possible to significantly improve the quality of the decrypted image by introducing a simple nonlinear operation in the encrypted function that contains the joint power spectrum. This nonlinearity also makes the system more resistant to chosen-plaintext attacks. We additionally explore the system resistance against this type of attack when a variety of probability density functions are used to generate the two random phase masks of the encryption–decryption process. Numerical results are presented and discussed.

Nonlinear optical security system based on a joint transform correlator in the Fresnel domain

Abstract: A new optical security system for image encryption based on a nonlinear joint transform correlator (JTC) in the Fresnel domain (FrD) is proposed. The proposal of the encryption process is a lensless optical system that produces a real encrypted image and is a simplified version of some previous JTC-based encryption systems. We use a random complex mask as the key in the nonlinear system for the purpose of increasing the security of the encrypted image. In order to retrieve the primary image in the decryption process, a nonlinear operation has to be introduced in the encrypted function. The optical decryption process is implemented through the Fresnel transform and the fractional Fourier transform. The security system proposed in this paper preserves the shift-invariance property of the JTC-based encryption system in the Fourier domain, with respect to the lateral displacement of the key random mask in the decryption process. This system shows an improved resistance to chosen-plaintext and known-plaintext attacks, as they have been proposed in the cryptanalysis of the JTC encrypting system. Numerical simulations show the validity of this new optical security system.

Multifactor authentication reinforces optical security

Abstract: A new optical method to obtain multifactor image encoding and authentication is proposed. The encoded complex-amplitude image function fulfills the general requirements of invisible content, extreme difficulty in copying or counterfeiting, and real-time automatic verification. This optical technique is attractive for high-security purposes that require multifactor reliable authentication. A demonstration using a combination of biometric images and key codes is provided. Retina images, which are very effective for authentication, are used as biometric signals. To the best of our knowledge, this is the first report on combined multiple signal encoding and simultaneous AND authentications for optical security reinforcement.