5,971 research outputs found
Adaptive polyphase subband decomposition structures for image compression
Cataloged from PDF version of article.Subband decomposition techniques have been extensively used for data coding and analysis. In most filter
banks, the goal is to obtain subsampled signals corresponding to different spectral regions of the original data. However, this approach leads to various artifacts in images having spatially varying characteristics, such as images containing text, subtitles, or sharp edges. In this paper, adaptive filter banks with perfect reconstruction property are presented for such images. The filters of the decomposition structure which can be either linear or nonlinear vary according to the nature of the signal. This leads to improved image compression ratios. Simulation examples are presented
A 2-D orientation-adaptive prediction filter in lifting structures for image coding
Cataloged from PDF version of article.Lifting-style implementations of wavelets are widely used in image coders. A two-dimensional (2-D) edge adaptive lifting structure, which is similar to Daubechies 5/3 wavelet, is presented. The 2-D prediction filter predicts the value of the next polyphase component according to an edge orientation estimator of the image. Consequently, the prediction domain is allowed to rotate ±45° in regions with diagonal gradient. The gradient estimator is computationally inexpensive with additional costs of only six subtractions per lifting instruction, and no multiplications are required. © 2006 IEEE
Nonlinear subband decomposition structures in GF-(N) arithmetic
Cataloged from PDF version of article.In this paper, perfect reconstruction filter bank structures for GF-(N) fields are developed. The new filter banks are based on the nonlinear subband decomposition and they are especially useful to process binary images such as document and fingerprint images. (C) 1998 Elsevier Science B.V. All rights reserved
Block wavelet transforms for image coding
Cataloged from PDF version of article.In this paper, a new class of block transforms is presented.
These transforms are constructed from subband decomposition filter
banks corresponding to regular wavelets. New transforms are compared
to the discrete cosine transform (DCT). Image coding schemes that
employ the block wavelet transform (BWT) are developed. BWT's can be
implemented by fast (O(N log N)) algorithms
Cumulant based identification approaches for nonminimum phase FIR systems
Cataloged from PDF version of article.In this paper, recursive and least squares methods
for identification of nonminimum phase linear time-invariant
(NMP-LTI) FIR systems are developed. The methods utilize the
second- and third-order cumulants of the output of the FIR
system whose input is an independent, identically distributed
(i.i.d.) non-Gaussian process. Since knowledge of the system
order is of utmost importance to many system identification algorithms,
new procedures for determining the order of an FIR
system using only the output cumulants are also presented. To
illustrate the effectiveness of our methods, various simulation
examples are presented
Motion-compensated prediction based algorithm for medical image sequence compression
Cataloged from PDF version of article.A method for irreversible compression of medical image sequences is described. The method relies on discrete cosine
transform and motion-compensated prediction to reduce intra- and inter-frame redundancies in medical image sequences.
Simulation examples are presented
A note on the (h,q)-Zeta type function with weight alpha
The objective of this paper is to derive symmetric property of (h,q)-Zeta
function with weight alpha. By using this property, we give some interesting
identities for (h,q)-Genocchi polynomials with weight alpha. As a result, our
applications possess a number of interesting property which we state in this
paper.Comment: 7 page
Detection of microcalcifications in mammograms using higher order statistics
Cataloged from PDF version of article.A new method for detecting microcalcifications in
mammograms is described. In this method, the mammogram image
is first processed by a subband decomposition filterbank. The
bandpass subimage is divided into overlapping square regions
in which skewness and kurtosis as measures of the asymmetry
and impulsiveness of the distribution are estimated. The detection
method utilizes these two parameters. A region with high
positive skewness and kurtosis is marked as a region of interest.
Simulation results show that this method is successful in detecting
regions with microcalcifications
Content-adaptive color transform for image compression
Cataloged from PDF version of article.In this paper, an adaptive color transform for image compression
is introduced. In each block of the image, coefficients of the color
transform are determined from the previously compressed neighboring
blocks using weighted sums of the RGB pixel values, making the transform
block-specific. There is no need to transmit or store the transform coeffi-
cients because they are estimated from previous blocks. The compression
efficiency of the transform is demonstrated using the JPEG image coding
scheme. In general, the suggested transformation results in better peak
signal-to-noise ratio (PSNR) values for a given compression level. ( C) 2011
Society of Photo-Optical Instrumentation Engineer
Subband domain coding of binary textual images for document archiving
Cataloged from PDF version of article.In this work, a subband domain textual image compression
method is developed. The document image is first decomposed into
subimages using binary subband decompositions. Next, the character
locations in the subbands and the symbol library consisting of the
character images are encoded. The method is suitable for keyword search
in the compressed data. It is observed that very high compression ratios
are obtained with this method. Simulation studies are presented
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