Giuseppe Spagnolo - Academia.edu (original) (raw)

Papers by Giuseppe Spagnolo

Optics Communications, 2002

A digital white-light speckle system is proposed for measurements in free convection. White-light... more A digital white-light speckle system is proposed for measurements in free convection. White-light speckle photography has certain advantages with respect to traditional speckle photography. Theory of the method and its application to free convective flows in liquids are presented.

In this paper we propose an asymmetric cryptography as subset of digital hologram watermarking, w... more In this paper we propose an asymmetric cryptography as subset of digital hologram watermarking, which is able to detect malicious tampering while tolerating some incidental distortions. It is a fragile watermark; in fact the mark is readily altered or destroyed when the host image is modified through a linear or nonlinear transformation. The proposed technique could be applied to Color Images as well as to Gray Scale ones. Using digital hologram watermarking, the embedded mark could be easily recovered by means of a Fourier Transform. Due to this fact the host image can be tampered and watermarked with the same holographic pattern. To avoid this possibility we have introduced an encryption method using an asymmetric Cryptography. The proposed scheme is based on the knowledge of original mark from the Authentication Entity, for applying Image Correlation between this and the extracted one.

Proceedings of Spie the International Society For Optical Engineering, Sep 1, 2005

In order to measure small diffusion coefficients of miscible fluids, in this paper we propose an ... more In order to measure small diffusion coefficients of miscible fluids, in this paper we propose an improved version of digital projection moiré. The system uses a simple and flexible fringe generator realized by means of a video projector with a modification of projection optic. The fringe patterns are projected on the bottom of a ground glass plate. The phase object (diffusion cell) is placed in front of the ground glass (in other words, in front of the fringe pattern), which is imaged by a digital video camera. Grating patterns, during the evolution of diffusion phenomena, are captured by a CCD camera and stored in a computer at different times. With the aid of signal demodulating techniques, the images are processed to obtain the diffusion coefficients. The theoretical aspects of the method are presented and the relationship between the fringe shift and the diffusion coefficient is derived. Furthermore, we report some experiments conducted for demonstrating the usefulness of the system.

Meas Sci Technol, 2000

In this work, we use the diffraction properties of gratings (Talbot effect) to obtain a distance ... more In this work, we use the diffraction properties of gratings (Talbot effect) to obtain a distance measurement through a Fourier transform method. The proposed technique is easy to use and requires low mechanical stability. Furthermore, it is suitable for out-of-laboratory applications and provides real-time (frame refresh) data acquisition capability.

Proceedings of Spie the International Society For Optical Engineering, Jun 25, 2003

Physical access to historic and artistic manufactures can be limited by a lot of factors. In part... more Physical access to historic and artistic manufactures can be limited by a lot of factors. In particular, the access to the collection of the ancient coins is difficult, especially for students. Indeed, for coins digital archive of high quality three-dimensional model and remote fruition is of great interest. In this work we propose 3D acquisition and digitizing techniques for the virtualized reality of ancient coins (virtual gallery). The system used for creating 3D shape of coins is based on conoscopic holography. This technique is a non-contact three-dimensional measuring technique that makes possible to produce holograms, even with incoherent light, with fringe periods that can be measured precisely to determine the exact distance to the point measured. It is suitable to obtain 3D profile with high resolution also on surface with unevenness reflectivity (this situation is usual on the surface of the ancient coins). By conoscopic holography, high-resolution 3D model can be obtained. However, accurate representation and high-quality display are fundamental requirements to avoid misinterpretation of the data. Therefore, virtual galleries can be obtained through a procedure involving 3D acquisition, 3D model and visualization. In conclusion, we propose an optoelectronic application, integrated with multimedia techniques, in order to improve the access to collection of ancient coins belonging to museums or privates.

Proceedings of Spie the International Society For Optical Engineering, Feb 2, 2006

Fragile watermark is designed to detect slight changes to the watermarked image with high probabi... more Fragile watermark is designed to detect slight changes to the watermarked image with high probability. In the security community, an integrity service is unambiguously defined as one, which insures that the sent and received data are identical. This binary definition can also be applicable to images; however it is too strict and not well adapted to this type of digital document. Indeed, in real life situations, images will be transformed. Their pixel values will therefore be modified but not the actual semantic meaning of the image. In order to provide an authentication service for still images, it is important to distinguish between malicious manipulations, which consist of changing the content of the original image such as captions or faces, and manipulations related to the use of an image, such as format conversion, compression, filtering, and so on. Unfortunately this distinction is not always clear; it partly depends on the type of image and its use. Scope of this paper is to present potentiality of Holographic technique in fragile watermarking for digital image authentication of medical or military images.

Meas Sci Technol, 2010

Nowadays all the National Central Banks are continuously studying innovative anti-counterfeiting ... more Nowadays all the National Central Banks are continuously studying innovative anti-counterfeiting systems for banknotes. In this note, an innovative solution is proposed, which combines the potentiality of a hylemetric approach (methodology conceptually similar to biometry), based on notes' intrinsic characteristics, with a well-known and consolidated 2D barcode identification system. In particular, in this note we propose to extract from the banknotes a univocal binary control sequence (template) and insert an encrypted version of it in a barcode printed on the same banknote. For a more acceptable look and feel of a banknote, the superposed barcode can be stamped using IR ink that is visible to near-IR image sensors. This makes the banknote verification simpler.

Measurement Science and Technology, Aug 24, 2010

ABSTRACT Nowadays all the National Central Banks are continuously studying innovative anti-counte... more ABSTRACT Nowadays all the National Central Banks are continuously studying innovative anti-counterfeiting systems for banknotes. In this note, an innovative solution is proposed, which combines the potentiality of a hylemetric approach (methodology conceptually similar to biometry), based on notes' intrinsic characteristics, with a well-known and consolidated 2D barcode identification system. In particular, in this note we propose to extract from the banknotes a univocal binary control sequence (template) and insert an encrypted version of it in a barcode printed on the same banknote. For a more acceptable look and feel of a banknote, the superposed barcode can be stamped using IR ink that is visible to near-IR image sensors. This makes the banknote verification simpler.

The European Physical Journal Applied Physics, May 31, 1999

An electronic speckle-pattern shearing interferometer (ESPSI) is proposed for measuring the free ... more An electronic speckle-pattern shearing interferometer (ESPSI) is proposed for measuring the free convection heat transfer coefficient in liquids. The heat transfer coefficient may be deduced by a simple manipulation of the speckle patterns. Theory of the method as well as its application are presented. The method is robust and easy to use for non-skilled operators.

In many cases, forensic scientists rely on measurements as a basis for their opinions. In the pas... more In many cases, forensic scientists rely on measurements as a basis for their opinions. In the past, forensic scientists, testifying about such measurements, have often presented the court with a single point value. The problem is that there is an unavoidable and an inherent element of uncertainty in every measurement. The metrology has developed several methods of quantifying a measurement's margin of error or uncertainty. By using these methods, the testifying expert can put the trier in a much better position to determine the appropriate evidentiary weight of the measurement. The purpose of this paper is to describe the problem of uncertainty in forensic science and in particular uncertainty in measurements by forensic scientists. In this paper, the problem of uncertainty is described in a relatively non-technical way. In other words, the discussion will focus on concepts rather than on analytical analysis.

Optical Engineering, 2001

Sandwich holography is proposed for simultaneous temperature mapping and heat transfer coefficien... more Sandwich holography is proposed for simultaneous temperature mapping and heat transfer coefficient measurement. The latter task requires the knowledge of the temperature gradient. The remarkable feature of the proposed method is that the temperature gradient is obtained avoiding numerical differentiation, which adds errors to the measured data, as well as phase extraction and phase unwrapping procedures. Theory and experimental results are given.

The Journal of Neuropsychiatry and Clinical Neurosciences, Oct 15, 2014

Int J Heat Mass Transfer, 2003

The onset and development of heat convection from a suddenly heated thin horizontal wire in air h... more The onset and development of heat convection from a suddenly heated thin horizontal wire in air has been studied experimentally by an optical technique, named dynamic electronic speckle pattern interferometry, which allows the acquisition of qualitative and quantitative data. Attention is focused in providing temperature field visualizations and data about the temporal behavior. The heat-rate-based Rayleigh number, Ra∗, ranges from 0.069 to 0.67, a region of parameters poorly covered by previous investigations. Experimental results are compared with previous data. The extent, at which existing correlations can be used for wires of 0.2 and 0.4 mm in diameter, is outlined. A new correlation is proposed.

Journal of Optics a Pure and Applied Optics, Aug 8, 2004

For legal purposes there is a requirement for the validation of signatures and handwritten docume... more For legal purposes there is a requirement for the validation of signatures and handwritten documents. A helpful method in this respect is the so-called superposed strokes analysis, based on the observation of some characteristics in the writing, such as some letters and their dynamics. This paper introduces a promising new technique for superposed strokes analysis based on conoscopic holography. Through a non-contact 3D measure a 3D profile is created of the superposed strokes that allows the writing dynamics to be determined, such as, for example, if a stroke was drawn clockwise or counterclockwise. We propose a 3D analysis by an opto-electronic system, in order to improve the graphology analysis for off-line signature verification.

J Opt, 1998

In this work, electro-optic holography is proposed as a diagnostic tool to evaluate the state of ... more In this work, electro-optic holography is proposed as a diagnostic tool to evaluate the state of conservation of mosaics. Some experimental results are given.