scholarly journals Global model for uneven illumination enhancement of document images

2020 ◽  
Author(s):  
Moad Hakim ◽  
Fatim Zahra Ait Bella ◽  
Idriss El Mourabit ◽  
Said Raghay
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Visual Recognition ◽  
Low Cost ◽  
Computational Photography ◽  
Optimization Techniques ◽  
Digital Imagery ◽  
Document Images ◽  
Low Contrast ◽  
Variable Illumination

Abstract Exponential growth of low-cost digital imagery is latterly observed. Images acquired under uneven lighting are prone to experience poor visibility, which may severely limit the performance of most computational photography and automatic visual recognition applications. Different from current optimization techniques, we design a novel partial differential equation based model to rectify the variable illumination artifacts. In this study, a large number of document samples capturing uneven illumination and low contrast conditions are tested to compare the effectiveness of the proposed local and nonlocal approaches. The suggested algorithm can be applied in Arabic, Latin and Chinese document images with any type of shade.

Symmetrical Fourth-Order Partial Differential Equation De-Noise for THz Pulse Imaging

2014 ◽  
Vol 631-632 ◽  
pp. 502-507
Author(s):  
Hai Tao Xing ◽  
Jian Jun Liu ◽  
Chao Yang Chen ◽  
Yong Du
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Fourth Order ◽  
Order Partial Differential Equation ◽  
Thz Imaging ◽  
Image Block ◽  
Partial Differential ◽  
Low Contrast ◽  
Significant Interest ◽  
Sharp Edges

Over past several years, there has been a significant interest in employing terahertz (THz) imaging technology. Due to low contrast and bit noise in scanning THz pulse imaging, a novel fourth-order partial differential equation (PDE) denosing algorithm is proposed in this paper. The proposed approach is capable of overcoming THz pulse image block suppressing noise and preserving the sharp edges at the same time. A symmetric discrete algorithm based on four-neighbor system is developed to solve the new model. Median filtering is applied to alleviate the speckle effects in the processed image at last. Experimental results are provided to show that the proposed approach outperforms the image denoising approaches developed in the literature, which is useful for further image processing and recognition.

scholarly journals Optimization of Complex Geometry Using Tenth Order Partial Differential Equation

2018 ◽  
Vol 2 (2) ◽  
pp. 23-31
Author(s):  
Syed Khawar Nadeem Kirmani ◽  
Raja Noshad Jamil
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Design Optimization ◽  
Complex Geometry ◽  
Optimization Techniques ◽  
Design Parameters ◽  
Order Partial Differential Equation ◽  
Partial Differential ◽  
Complex Shapes ◽  
Shape Parameterization

This paper presents an efficient and intuitive technique of shape parameterization for design optimization using a partial differential equation (PDE) of order ten. It shows how the choice of two introduced parameters can enable one to parameterize complex geometries. With the use of PDE based formulation, it is shown in this paper how the shape can be defined and manipulated on the basis of parameterization and the boundary value approaches by which complex shapes can be created. Further the boundary conditions which are used in it are a boundary and an intermediate curves for defining the shape. This technique allows complex shapes to be parameterized intuitively using a very small set of design parameters. Hence, Practical design optimization of problems becomes more achievable by applying PDE based approach of shape parameterization by incorporating standard numerical optimization techniques.

Qxygen transfer in gravity flow sewers

2000 ◽  
Vol 42 (3-4) ◽  
pp. 417-422 ◽  
Author(s):  
T.Y. Pai ◽  
C.F. Ouyang ◽  
Y.C. Liao ◽  
H.G. Leu
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Dissolved Oxygen ◽  
Flow Velocity ◽  
Molecular Diffusion ◽  
Eddy Diffusion ◽  
Partial Differential ◽  
Diffusion Term ◽  
Sewer Pipes ◽  
Gravity Sewer

Oxygen diffused to water in gravity sewer pipes was studied in a 21 m long, 0.15 m diameter model sewer. At first, the sodium sulfide was added into the clean water to deoxygenate, then the pump was started to recirculate the water and the deoxygenated water was reaerated. The dissolved oxygen microelectrode was installed to measure the dissolved oxygen concentrations varied with flow velocity, time and depth. The dissolved oxygen concentration profiles were constructed and observed. The partial differential equation diffusion model that considered Fick's law including the molecular diffusion term and eddy diffusion term were derived. The analytic solution of the partial differential equation was used to determine the diffusivities by the method of nonlinear regression. The diffusivity values for the oxygen transfer was found to be a function of molecular diffusion, eddy diffusion and flow velocity.

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