60,626 research outputs found
Handwritten Arabic character recognition: which feature extraction method?
Recognition of Arabic handwriting characters is a difficult task due to similar appearance of some different characters. However, the selection of the method for feature extraction remains the most important step for achieving high recognition accuracy. The purpose of this paper is to compare the effectiveness of Discrete Cosine Transform and Discrete Wavelet transform to capture discriminative features of Arabic handwritten characters. A new database containing 5600 characters covering all shapes of Arabic handwriting characters has also developed for the purpose of the analysis. The coefficients of both techniques have been used for classification based on a Artificial Neural Network implementation. The results have been analysed and the finding have demonstrated that a Discrete Cosine Transform based feature extraction yields a superior recognition than its counterpart
Type-IV DCT, DST, and MDCT algorithms with reduced numbers of arithmetic operations
We present algorithms for the type-IV discrete cosine transform (DCT-IV) and
discrete sine transform (DST-IV), as well as for the modified discrete cosine
transform (MDCT) and its inverse, that achieve a lower count of real
multiplications and additions than previously published algorithms, without
sacrificing numerical accuracy. Asymptotically, the operation count is reduced
from ~2NlogN to ~(17/9)NlogN for a power-of-two transform size N, and the exact
count is strictly lowered for all N > 4. These results are derived by
considering the DCT to be a special case of a DFT of length 8N, with certain
symmetries, and then pruning redundant operations from a recent improved fast
Fourier transform algorithm (based on a recursive rescaling of the
conjugate-pair split radix algorithm). The improved algorithms for DST-IV and
MDCT follow immediately from the improved count for the DCT-IV.Comment: 11 page
Evolution of the discrete cosine transform using genetic programming
Compression of 2 dimensional data is important for the efficient transmission, storage and manipulation
of Images. The most common technique used for lossy image compression relies on fast application of
the Discrete Cosine Transform (DCT). The cosine transform has been heavily researched and many
efficient methods have been determined and successfully applied in practice; this paper presents a novel
method for evolving a DCT algorithm using genetic programming. We show that it is possible to evolve a
very close approximation to a 4 point transform. In theory, an 8 point transform could also be evolved
using the same technique
Investigation of the effects on embedded watermarks under image manipulations
Abstract: In this paper, different types of image watermarking techniques, the embedding of data or copyright information into the data file, are investigated. Three image watermarking techniques are discussed, namely: least significant bit, least significant bit and discrete cosine transform combined, and discrete cosine transform and discrete wavelet transform combined. These embedded watermarking techniques are evaluated on how robust each technique is under image manipulations. Simulations are done using the three image watermarking techniques to determine the effects on how well the embedded watermarking technique resists manipulations..
Algebraic Signal Processing Theory: Cooley-Tukey Type Algorithms for Polynomial Transforms Based on Induction
A polynomial transform is the multiplication of an input vector x\in\C^n by
a matrix \PT_{b,\alpha}\in\C^{n\times n}, whose -th element is
defined as for polynomials p_\ell(x)\in\C[x] from a list
and sample points \alpha_k\in\C from a list
. Such transforms find applications in
the areas of signal processing, data compression, and function interpolation.
Important examples include the discrete Fourier and cosine transforms. In this
paper we introduce a novel technique to derive fast algorithms for polynomial
transforms. The technique uses the relationship between polynomial transforms
and the representation theory of polynomial algebras. Specifically, we derive
algorithms by decomposing the regular modules of these algebras as a stepwise
induction. As an application, we derive novel general-radix
algorithms for the discrete Fourier transform and the discrete cosine transform
of type 4.Comment: 19 pages. Submitted to SIAM Journal on Matrix Analysis and
Application
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