Lorenzo Mattos

Digital Images Phase Encryption Using Fractional Fourier Transform

In the present paper the fractional Fourier transform was used to make phase encryption of color digital images. The image to encrypt is placed as the phase of a complex exponential, then is fractionally transformed three times and multiplied in intermediate steps by two statistically independent random phase masks thus to obtain the encrypted image, to decrypt the coding image the encryption procedure is applied in the inverse sense to the conjugated complex of the encrypted image, then is taken the negative of the phase of the resulting function from the decryption process and the original image is obtained this way that had been encrypted. The use of the fractional Fourier transform and the phase encryption of the image add much more complexity to the decryption of the image to who wants decrypt it without being authorized. In the cryptographic algorithm implemented five keys are used, made up of three fractional orders and two random phase masks, all these keys are necessary for proper decryption affording reliability to image transference via transmission networks

Image encryption using the fractional wavelet transform

In this paper a technique for the coding of digital images is developed using Fractional Wavelet Transform (FWT) and random phase masks (RPMs). The digital image to encrypt is transformed with the FWT, after the coefficients resulting from the FWT (Approximation, Details: Horizontal, vertical and diagonal) are multiplied each one by different RPMs (statistically independent) and these latest results is applied an Inverse Wavelet Transform (IWT), obtaining the encrypted digital image. The decryption technique is the same encryption technique in reverse sense. This technique provides immediate advantages security compared to conventional techniques, in this technique the mother wavelet family and fractional orders associated with the FWT are additional keys that make access difficult to information to an unauthorized person (besides the RPMs used), thereby the level of encryption security is extraordinarily increased. In this work the mathematical support for the use of the FWT in the computational algorithm for the encryption is also developed.

Fractional Hartley transform applied to optical image encryption

A new method for image encryption is introduced on the basis of two-dimensional (2-D) generalization of 1-D fractional Hartley transform that has been redefined recently in search of its inverse transform We encrypt the image by two fractional orders and random phase codes. It has an advantage over Hartley transform, for its fractional orders can also be used as addictional keys, and that, of course, strengthens image security. Only when all of these keys are correct, can the image be well decrypted. Computer simulations are also perfomed to confirm the possibilty of proposed method.

Sign Language Recognition System using Neural Network for Digital Hardware Implementation

This work presents an image pattern recognition system using neural network for the identification of sign language to deaf people. The system has several stored image that show the specific symbol in this kind of language, which is employed to teach a multilayer neural network using a back propagation algorithm. Initially, the images are processed to adapt them and to improve the performance of discriminating of the network, including in this process of filtering, reduction and elimination noise algorithms as well as edge detection. The system is evaluated using the signs without including movement in their representation.

Design and implementation in VHDL code of the two- dimensional fast Fourier transform for frequency filtering, convolution and correlation operations

The two-dimensional Fast Fourier Transform (FFT 2D) is an essential tool in the two-dimensional discrete signals analysis and processing, which allows developing a large number of applications. This article shows the description and synthesis in VHDL code of the FFT 2D with fixed point binary representation using the programming tool Simulink HDL Coder of Matlab; showing a quick and easy way to handle overflow, underflow and the creation registers, adders and multipliers of complex data in VHDL and as well as the generation of test bench for verification of the codes generated in the ModelSim tool. The main objective of development of the hardware architecture of the FFT 2D focuses on the subsequent completion of the following operations applied to images: frequency filtering, convolution and correlation. The description and synthesis of the hardware architecture uses the XC3S1200E family Spartan 3E FPGA from Xilinx Manufacturer.

Template characterization and correlation algorithm created from segmentation for the iris biometric authentication based on analysis of textures implemented on a FPGA

Among the most used biometric signals to set personal security permissions, taker increasingly importance biometric iris recognition based on their textures and images of blood vessels due to the rich in these two unique characteristics that are unique to each individual. This paper presents an implementation of an algorithm characterization and correlation of templates created for biometric authentication based on iris texture analysis programmed on a FPGA (Field Programmable Gate Array), authentication is based on processes like characterization methods based on frequency analysis of the sample, and frequency correlation to obtain the expected results of authentication.

Detection of wavelengths in the visible range using fiber optic sensors

This paper shows the design and implementation of a fiber optic sensor for detecting and identifying wavelengths in the visible range. The system consists of a diffuse optical fiber, a conventional laser diode 650nm, 2.5mW of power, an ambient light sensor LX1972, a PIC 18F2550 and LCD screen for viewing. The principle used in the detection of the lambda is based on specular reflection and absorption. The optoelectronic device designed and built used the absorption and reflection properties of the material under study, having as active optical medium a bifurcated optical fiber, which is optically coupled to an ambient light sensor, which makes the conversion of light signals to electricas, procedure performed by a microcontroller, which acquires and processes the signal. To verify correct operation of the assembly were utilized the color cards of sewing thread and nail polish as samples for analysis. This optoelectronic device can be used in many applications such as quality control of industrial processes, classification of corks or bottle caps, color quality of textiles, sugar solutions, polymers and food among others.

Simple method of fabrication tapered fiber

This paper presents a simple method for manufacturing fiber tapered through elongation, by the combination of heating with a butane torch and controlled stretch. Reducing the diameter of the multimode fiber of 100 microns to 10 microns, the displacement of the fiber is performed through bipolar stepping motors with one driver L293B and one PIC16F628A microcontroller for controlling movement. The system allows control of the desired fiber diameter up to 10 microns; the results are seen in a microscope and a rule of separation 2.5μm micrometer to calculate the diameter of the fiber.

Automated coal petrography for macerals characterization using histograms technique

Coal composition is popularly characterized in terms of macerals which are the microscopically recognizable individual constituents of coal; petrographic studies are mainly used for determining coal quality, coking properties and composition or coal rank (Taylor et al., 1998); maceral analysis can be carried out using manual and automated techniques, although both have drawbacks. Manual analysis is time consuming and unavoidably subjective, especially when comparing results of different analysts. Automated analysis is one possible alternative to manual analysis but is not without its difficulties, especially when resolving the various macerals from each other and from the support media used to suspend the coal in a polished block; the smallest microscopically recognizable entities in coal are called macerals, they are analogous to minerals in rocks. However they differ since minerals have an homogeneous chemistry and an orderly internal structure. Coal macerals are distinguished by their optical characteristics of color, relief of the polished surface, morphology, reflectance and fluorescence. A coal reflectogram (histogram) provides the reflectance distribution of coal sample in the form of a frequency histogram, the present work aims to study the macerals histograms in order to implemented this tool in petrographic analysis and coal characterization.

Fingerprint verification by correlation using wavelet compression of preprocessing digital images

In this paper, we implemented a practical digital security system that combines digital correlation, wavelet compression with digital images preprocessing. The system has a biometric sensor; it is charge to capture the images and to digitize them. These images are preprocessed using wavelet based image compression and are skeleting for to stand out elements of the image that are considered of greater importance, eliminating the undesired signals, that because of the method of acquisition, or the conditions under which it was captured they appear in the same one. These images are stored in the data base, which to the being passed through different algorithms makes a compound filter, that serves as reference or pattern fingerprint for making the comparisons. These comparisons are showing in a graph where are observed amplitude different for each one from fingerprint, this make with help Fourier transformed and the correlation operations that allows quantifying the degree of similarity between two images. Depending on the results thrown by the system at the time of comparing a new fingerprint with the compound filter the access will be allowed or not the user.