Chom Kimpan

Handwritten Thai Character Recognition Using Fourier Descriptors and Genetic Neural Networks

This article presents a method to solve the rotated and scaling character recognition problem using Fourier descriptors and genetic neural networks. The contours of character image are extracted and separated between the outer contour and inner or loop contours. The loop contours are a special characteristic of Thai characters, called the head of the character. The special features of Thai characters (loop contours) are used at the rough classification stage, and Fourier descriptors with genetic neural networks are used at the fine classification stage. The Fourier descriptors detect the outer contour of a character and it is fed to network. These features are recognized by a multilayer neural network. Genetic algorithms (GAs) are utilized to help compute the weights of the neural network optimally and reduce uncertain states in the neural networks output. Experimental results have shown that the combination of the Fourier descriptors with genetic neural networks, loop features, and local curvature charateristics of similar characters are powerful tools for successfully classifying Thai characters. The recognition rate by this method is 99.12% for 1200 examples of handwritten Thai words (a total of 13,500 characters) written by 60 persons.

Printed Thai character recognition using topological properties method

This paper describes a printed Thai character recognition method which uses topological properties. The recognition system is divided into two stages. In the rough classification stage, a thinning technique is applied to eliminate noise and fine features. The thinned characters are separated into cluster domains by using a linear decision function based on the height and width of each character. In the fine classification stage, the ‘connected numbers’ of points in the character pattern are computed. Topological properties are then used to distinguish between the characters.

3-D object recognition from shadow shape curves

The 3-D object recognition can be normally done by collecting 2-D projections taken at various viewing angles, which requires a large size of database. In this paper we present the 3-D object-recognition approach by analyzing the shadow shape curve of 2-D from horizontal 360/spl deg/ viewing angles, projections which depend on typical characters of objects. The process starts from shooting the subject with the light source behind the subject or a subject with a light background while the subject is being turned around in various viewing angles. The process is independent of the size of the shadow shape curves or position of the subject taken. This process shows the shadow shape curves which are then converted to patterns of slope scores and later matched with the standard slope score patterns in the database. By comparing the sequential aspects of the figure members in the slope patterns with the standard ones, this process can recognize 3-D objects with better than 92 percent of accuracy.

Blocking probability of the reverse link cellular CDMA system

The blocking probability of the reverse link cellular CDMA system is presented. Gaussian and lognormal approximation are the methods for determination of blocking probability. In the analysis in this paper, the parameter for the number of resolvable paths over a Rayleigh multipath fading channel is presented. In addition, we also show the effect of power control errors.

K-MEANS BASED IMAGE DENOISING USING BILATERAL FILTERING AND TOTAL VARIATION

Bilateral filter and Total variation image denoising are widely used in image denoising. In low noisy level, bilateral filtering is better than TV denoising for it reveals better SNR and sharper edges. However, in high noisy level, TV denoising outperforms bilateral filtering in terms of SNR and more details of non edges. It is very difficult to perform denoising of a very noisy image for the resulted image rarely improves its SNR comparing to the original noisy one. Even though Total variation image denoising could be used for a very noisy image, the resulted SNR still needs some improvement. In this research, the K-means-based Bilateral-TV denoising (K-BiTV) approach using pixel-wise bilateral filtering and TV denoising has been derived based on the gradient magnitude calculation of the guideline map using K-means clusters. The denoising result of K-BiTV was depended on the level of noise density and the appropriate cluster. The experimental result showed that comparing to the conventional TV denoising and bilateral filter, K-BiTV gave the higher SNRs for some images with higher level of noise density.

Effect of multipath fading on the Erlang capacity of imperfect power control in cellular CDMA system

This paper presents an approach to the evaluation of the reverse link capacity of a cellular CDMA system, which is based on using Gaussian and lognormal approximations. We include the fading channel multipath intensity profile (MIP) shape factor in the Erlang capacity formula. Imperfect power control and Rayleigh multipath fading channels are considered.

Outage probability of the overlapped carriers allocation scheme with imperfect power control in DS-CDMA

The outage probability is investigated in cellular FD/CDMA (frequency division/code division multiple access) in terms of the SNR under the overlapped carrier allocation scheme in the reverse link of a cellular radio system, which is based on using Gaussian and lognormal approximations, respectively. In numerical results, the bandlimited pulse generated by raised cosine pulse shaping filters (SRRC) of the transmitted signal is investigated and compared in conventional FD/CDMA and OC-CDMA (overlapping carrier CDMA) for the outage probability. It is also shown that the outage probability can be improved by overlapping of carriers.

Outage probability, throughput and delay analysis of cellular DS-CDMA system in the presence of correlated signal and interference

In this paper, we evaluate the performance of a cellular DS-CDMA system, by taking into account the correlation between signal and interference, to determined outage probability, throughput and delay for the reverse link with power control error. The numerical results show that when the correlation is considered the outage probability decreased, the throughput value increased, that is, the performance can be achieved.

Capacity analysis of forward-link in DS-CDMA cellular system with power control

In this paper, we analyze the forward-link capacity of a cellular DS-CDMA system, especially the effects of power control, path loss exponent (/spl gamma/) and orthogonality factor (f/sub 0/) of multipath propagation on the system. The problem of finding an optimum power control factor (n) is evaluated. According to n, the proper threshold distance is estimated for optimum performance. With these factors, the numerical results show that the capacity is reduced by changing f/sub 0/ from 0.7 to 0.2 and /spl gamma/ from 5 to 3.