An important factor to improve the visual quality of an image is contrast enhancement. The more the value of contrast, the simpler it is to identify and compare between different objects in an image. This paper focuses on experimenting how efficient different contrast enhancement techniques developed for visual images work for infrared images. It also determines which technique suites well to s...

A region based illumination-normalization method which only uses gray level values in an image as information is proposed in this paper. The general purpose of illumination normalization is to reduce lighting effect when the testing images are captured in different environment and supplies useful and uniform data. We apply the algorithm in our face recognition system. The algorithm first divide...

We investigate new constructions of n-circular counterexamples with a focus on the case of n = 2. We have a particular interest in what qualities a cryptosystem must have to be able to separate such circular security from IND-CPA or IND-CCA security. To start, we ask whether there is something special about the asymmetry in bilinear groups that is inherent in the works of [1] and [16] or whethe...

The paper presents basic concepts of the discrete system theory from the viewpoint of Banach algebras and shows that some Banach algebras of sequences are not only suitable mathematical framework for the multidimensional discrete system theory but also open ways to new models of discrete systems and lead to hitherto unknown methods of homomorphic signal processing and deconvolution. Three Banac...

We investigated a number of image processing techniques for enhancing the retinal nerve fiber layer (NFL) in fundus photographs taken with red-free light. Wedge-type defects within the NFL were enhanced best by contrast enhancement algorithms such as histogram modification and extremum sharpening. Narrow, slitlike NFL defects can be enhanced by directional enhancement techniques. Normal NFL fea...

Privacy concerns are a major hurdle in the success of personalized services in ubiquitous computing environments. Personalized recommendations are usually served using Collaborative Filtering techniques. In this paper, we propose a framework for privacy preserving collaborative filtering in ubiquitous computing environments. The proposed framework is based on a biclustering algorithm which empl...

An identification method for uniform linear motion blurring direction based on second-order difference spectrum was proposed. The power spectrum of the blurred image was calculated after the Laplace second-order difference, and then the power spectrum was processed by the homomorphic filtering and the circular low-pass filtering. The blurring direction was attained by linear fitting of the freq...

For short rp-verberation times (~ 10 msec) t and over short intervals (~ 50 msec) , speech waveforms reverberated by small rooms can be approximated by the convolution of a function interpreted as the "room impulse response" with the uncorrupted speech. It is possible, therefore, to remove the effects of reverberation by applying a deconvolution process to 50-msec sections of reverberated wavef...

When a digital medical image is enhanced, the useful details of the image should be strengthened, but the details cannot be strengthened by these algorithms based on traditional illumination-reflection model. According to the imaging principle and medical requirement, wavelet illumination-reflection model and a new algorithm based on the model are proposed. The image is decomposed into illumina...

In this paper, we propose a novel technique to reconstruct 3D surface of an underwater object using stereo images. Reconstructing the 3D surface of an underwater object is really a challenging task due to degraded quality of underwater images. There are various reason of quality degradation of underwater images i. e. , non-uniform illumination of light on the surface of objects, scattering and ...