Sharif Digital Repository

Today digital imaging systems have been widely used due to their ease of use and proper costs, but still they suffer from low contrast and resolution. Because of technical limits and expensiveness of hardware, software techniques like super resolution have been used. By super resolution we mean increasing the density of an image’s pixels. Super resolution can be categorized as “single image super resolution” and “multi-image super resolution”. Single image super resolution is applied on a low quality image which has blur and/or noise of environment and imaging system and increases its quality and density to an acceptable level. In multi-image super resolution some auxiliary images captured... 

The emergence of complex equations in engineering sciences leads to development of numerical methods for solving these equations. Obviously, each of the proposed Algorithms and various methods in this field were evaluated according to the limitations of time, software and hardware and based on these limitations the advantages and disadvantages of these methods were determined. Direct Discrete method is one of the modern methods used in solving the conservation equations. In this method, in addition to the advantages of numerical methods, equations will be produced in discrete space to avoid involving with differential equations. This method was first studied in the field equations. The... 

white noise or an innovation process through an all-pole filter. Applications of these processes include speech processing, RADAR signals and stock market data modeling. There exists an extensive research material on the AR processes with Gaussian innovation, however studies about the non-Gaussian case have been much more limited, while in many applications the asymptotic behavior of the signal is non-Gaussian. Non-Gaussian processes have an advantage over Gaussian ones in being capable of modeling sparsity. Assuming an appropriate non-Gaussian innovation one can suggest a more realistic description of sparse signals and predict their behavior or estimate their unknown values successfully.... 

Diffusion Weighted Imaging (DWI) is a non-invasive method for investigating the brain white matter. Assuming the Gaussian model for diffusion process, diffusion tensor is constructed and Diffusion Tensor Images (DTI) are obtained. White matter is constructed from fiber bundles which have crossing in most of the regions. In the crossing regions, the Gaussian model cannot work. In this situation, DTI cannot reconstruct the fiber structures correctly. Therefore, High Angular Resolution Diffusion Imaging (HARDI) was proposed to solve this problem. Q-ball imaging is a new technique for HARDI reconstruction which is useful for estimating diffusion Orientation Distribution Function (ODF). ODF is a...