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Full-Text Articles in Signal Processing
Facial Features Localization In Front View Head And Shoulders Images, Adnan M. Alattar, Sarah A. Rajala
Facial Features Localization In Front View Head And Shoulders Images, Adnan M. Alattar, Sarah A. Rajala
Sarah A. Rajala
The computerized process of locating human facial features such as the eyes, nose and mouth in a head and shoulders image is crucial to such applications as automatic face identification and model-based video coding. A new model-based algorithm for locating these major features is developed. The algorithm estimates the parameters of the ellipse which best fits the head view in the image and uses these parameters to calculate the estimated locations of the facial features. It then refines the estimated coordinates of the eyes, mouth, and nose by exploiting the vertical and horizontal projections of the pixels in windows around …
Subband Absolute Moment Block Truncation Coding, Kai-Kuang Ma, Sarah A. Rajala
Subband Absolute Moment Block Truncation Coding, Kai-Kuang Ma, Sarah A. Rajala
Sarah A. Rajala
In this paper, a new subband coding system called subband absolute moment block truncation coding (SAMBTC) is introduced to compress monochrome images and color images recorded in YIQ and L*u*v* uniform color spaces. The SAMBTC incorporates full‐band absolute moment block truncation coding (AMBTC) into subbands along with a new subband dynamic bit allocation algorithm which is derived from the Shannon rate‐distortion bound. Simulation results show that the proposed Shannon/bound‐based bit allocation algorithm outperforms the commonly used standard‐deviation‐based bit allocation scheme. Compared with ABMTC, SAMBTC achieves superior imaging without blocking artifacts at low bit rates
Three-Dimensional Location Estimation Of Trajectories Of Point Targets Using A Projection-Based Transformation Method, Jae-Ho Choi, Sarah A. Rajala
Three-Dimensional Location Estimation Of Trajectories Of Point Targets Using A Projection-Based Transformation Method, Jae-Ho Choi, Sarah A. Rajala
Sarah A. Rajala
A new computational approach for determining the parameters that characterize the locations of trajectories of point targets in a 3-D space is described. The targets of concern are dim, unresolved point targets moving along straight paths across the same field of view. Since the target's signal-to-noise ratio is low and the spatial extent of the target is less than a pixel, one must rely on integration over a target track that spans many image frames. The proposed method estimates these parameters by transforming the entire set of time-sequential images of a constant field of view into the projection space by …
Impact Of Human Visual Perception Of Color On Very Low Bit-Rate Image Coding, Sarah A. Rajala
Impact Of Human Visual Perception Of Color On Very Low Bit-Rate Image Coding, Sarah A. Rajala
Sarah A. Rajala
One of the keys to obtaining acceptable quality imagery/video encoded at very low bit rates is to transmit only that information which is critical to human perception. To successfully achieve this goal, one must not only understand the human visual system, but be able to utilize this information in the design of their codec. This paper will present an overview of the properties associated with color science and human visual perception, and how they could make an impact on very low bit-rate image coding.
Reducing Respiratory Artifacts In Chest Mr Images Through Hybrid Space Motion Tracking And Postprocessing, John N. Campbell, Wesley E. Snyder, Peter Santago Ii, Sarah A. Rajala, Craig A. Hamilton
Reducing Respiratory Artifacts In Chest Mr Images Through Hybrid Space Motion Tracking And Postprocessing, John N. Campbell, Wesley E. Snyder, Peter Santago Ii, Sarah A. Rajala, Craig A. Hamilton
Sarah A. Rajala
A new postprocessing method of correcting for respiratory motion induced artifacts in MRI is presented. The motion of the chest during respiration is modeled as a combination of translation and dilation. Displacements of the chest wall are tracked via a thin, MR-sensitive plate placed on the patient's chest during a scan. Scanning with phase encoding left/right (L/R) and frequency encoding anterior/posterior (A/P) causes the motion artifacts to be repeated in the L/R direction, thus not overlapping on the plate. By performing the inverse A/P Fourier transform, the resulting hybrid space data has A/P spatial data and L/R spatial frequency data, …
Use Of Extrapolation In Computing Color Look-Up Tables, Sarah A. Rajala, H. Joel Trussell, Atish P. Kakodkar
Use Of Extrapolation In Computing Color Look-Up Tables, Sarah A. Rajala, H. Joel Trussell, Atish P. Kakodkar
Sarah A. Rajala
Colorimetric reproduction requires calibrated color output devices. One way to characterize a color output device is with a 3D look-up table which maps the tristimulus values, t, to the control values, c of the output device. The functional form of the output device can be written in vector notation as t equals F(c). The purpose of calibration is to define an inverse mapping from tristimulus values to control values. Since the function F((DOT)) has no closed form, it is defined by interpolation from a table of values. Given a set of control values ]ci[ on a regular grid and the …
Parallel Image Segmentation Using A Hopfield Neural Network With Annealing Schedule For Neural Gains, Yungsik Kim, Sarah A. Rajala
Parallel Image Segmentation Using A Hopfield Neural Network With Annealing Schedule For Neural Gains, Yungsik Kim, Sarah A. Rajala
Sarah A. Rajala
Neural network architectures have been proposed as new computer architectures and a Hopfield neural network has been shown to find good solutions very fast in solving complex optimization problems. It should be noted, however, that a Hopfield neural network with fixed neural gains only guarantees to find local optimum solutions, not the global optimum solution. Image segmentation, like other engineering problems, can be formalized as an optimization problem and implemented using neural network architectures if an appropriate optimization function is defined. To achieve a good image segmentation, the global or the nearly global optimum solutions of the appropriate optimization function …
Optimum Displacement Estimates Using Mean Field Annealing, Ikhlas M. Abdelqader, Sarah A. Rajala, Griff L. Bilbro, Wesley E. Snyder
Optimum Displacement Estimates Using Mean Field Annealing, Ikhlas M. Abdelqader, Sarah A. Rajala, Griff L. Bilbro, Wesley E. Snyder
Sarah A. Rajala
In this paper a new algorithm to estimate dense displacement fields from a sequence of images is developed. The algorithm is based on modeling the displacement fields as Markov Random fields. The Markov Random fields-Gibbs equivalence is then used to convert the problem into one of finding an appropriate energy function that describes the motion and any constraints imposed on it. Mean field annealing, a technique which finds global minima in nonconvex optimization problems, is used to minimize the energy function, and solve for the optimum displacement fields. The algorithm results in accurate estimates even for scenes with noise or …
Image Segmentation Using An Annealed Hopfield Neural Network, Yungsik Kim, Sarah A. Rajala
Image Segmentation Using An Annealed Hopfield Neural Network, Yungsik Kim, Sarah A. Rajala
Sarah A. Rajala
Good image segmentation can be achieved by finding the optimum solution to an appropriate energy function. A Hopfield neural network has been shown to solve complex optimization problems fast, but it only guarantees convergence to a local minimum of the optimization function. Alternatively, mean field annealing has been shown to reach the global or the nearly global optimum solution when solving optimization problems. Furthermore, it has been shown that there is a relationship between a Hopfield neural network and mean field annealing. In this paper, we combine the advantages of the Hopfield neural network and the mean field annealing algorithm …
Segmentation-Based Texture Coding Algorithm For Packet Video: A Goal-Oriented Approach, Day-Fann Shen, Sarah A. Rajala
Segmentation-Based Texture Coding Algorithm For Packet Video: A Goal-Oriented Approach, Day-Fann Shen, Sarah A. Rajala
Sarah A. Rajala
The design of an image coder for packet-switched transmission is formulated as a minimization problem. A general set of design requirements is derived and used to design a segmentation-based texture coding algorithm. The segmentation process is performed on a pyramid data structure and uses the just noticeable difference (JND) of the human visual system as the merge criterion. To reduce the bit-rate while maintaining image quality, each region is classified as either texture or non-texture. Texture regions are approximated by a one-dimensional polynomial, while the non-texture regions are approximated by the region's mean intensity. A set of parameters for bit-rate/image …
Tracking Of Unresolved Targets In Infrared Imagery Using A Projection-Based Method, Jae-Ho Choi, Sarah A. Rajala
Tracking Of Unresolved Targets In Infrared Imagery Using A Projection-Based Method, Jae-Ho Choi, Sarah A. Rajala
Sarah A. Rajala
The conventional two-dimensional Hough transform technique is generalized into a projection- based transform method by using the modified Radon transform for estimating a three- dimensional target tracks embedded in a time-sequential set of image frames. The target of concern are dim, unresolved point targets moving along straight paths across a same field of view. Since the target signal-to-noise is low and the spatial extend of the target is less than a pixel, one must rely on integration over a target track which span over many image frames. Instead of processing the entire 3-D data set, a set of projections are …
Segmentation-Based Motion Estimation And Residual Coding For Packet Video: A Goal-Oriented Approach, Day-Fann Shen, Sarah A. Rajala
Segmentation-Based Motion Estimation And Residual Coding For Packet Video: A Goal-Oriented Approach, Day-Fann Shen, Sarah A. Rajala
Sarah A. Rajala
Image transmission via packet switched networks has a significant impact on encoded image data. To develop an efficient image codec for packet video, the goals of image coding are redefined and formulated as an optimization problem. Guided by these goals, a set of design requirements and a new segmentation based coding technique is developed. This approach features region based motion estimation, region based residual coding and region based single frame coding. The performance of the proposed algorithm is evaluated and a packet loss compensation algorithm is presented. As a result, good image quality at very low-bit rates can be achieved.
Visual Sensitivity To Color-Varying Stimuli, Sarah A. Rajala, H. Joel Trussell, B. Krishnakumar
Visual Sensitivity To Color-Varying Stimuli, Sarah A. Rajala, H. Joel Trussell, B. Krishnakumar
Sarah A. Rajala
We present the results of a study of the sensitivity of the human visual system (HVS) to spatially varying color stimuli. Sinusoidal grating patterns of different spatial frequencies were presented to six observers and the contrast required to just distinguish the pattern from the surrounding uniform field was determined. Tables and curves of contrast (measured in ΔELab) as a function of frequency were generated at different values of; the orientation (horizontal, vertical and diagonal) of the pattern, the average luminance, the x and y chromaticity co-ordinates, and the direction of the variation of the stimulus in color space (luminance, red-green, …
Detection Of Unresolved Target Tracks In Infrared Imagery, Sarah A. Rajala, Loren W. Nolte, James V. Aanstoos
Detection Of Unresolved Target Tracks In Infrared Imagery, Sarah A. Rajala, Loren W. Nolte, James V. Aanstoos
Sarah A. Rajala
Two methods for detecting dim, unresolved target tracks in infrared imagery are presented. Detecting such targets in a sequence of noisy images is very challenging from the standpoint of algorithm design as well as detection performance evaluation. Since the signal-to-noise ratio per pixel is very low (a dim target) and the target is unresolved (of spatial extent less than a pixel), one must rely on integration over target tracks which span over many image frames. In addition, since there is a large amount of uncertainty as to the pattern and location of target tracks, good algorithms must consider a large …
Image Segmentation Using Human Visual System Properties With Applications In Image Compression, Heidi A. Peterson, Sarah A. Rajala, Edward J. Delp
Image Segmentation Using Human Visual System Properties With Applications In Image Compression, Heidi A. Peterson, Sarah A. Rajala, Edward J. Delp
Sarah A. Rajala
Many image compression techniques involve segmentation of a gray level image. With such techniques, information is extracted that describes the regions in the segmented image, and this information is then used to form a coded version of the image. In this paper we present a region-growing-based segmentation technique that incorporates human visual system properties, and describe the use of this technique in image compression. We also discuss the effect of requantizing a segmented image. Requantization of a segmented image is useful because it can lead to a reduction in the number of bits required to code the description of the …
Segmentation-Based Image Coding In A Packet-Switched Network Environment, Sarah A. Rajala, Wonrae M. Lee
Segmentation-Based Image Coding In A Packet-Switched Network Environment, Sarah A. Rajala, Wonrae M. Lee
Sarah A. Rajala
In this paper, a segmentation-based image coding technique incorporating properties of the human visual system is presented. The approach taken in this research is to first segment an image into regions with spatial similarity and then to define an efficient method for encoding the segmented image data. Furthermore, specific attention is given in this paper to defining the requirements for using a segmentation-based image coder for video transmission over a packet-switched network.
Second Generation Hybrid Image-Coding Techniques, M. Reha Civanlar, Sarah A. Rajala, Wonrae M. Lee
Second Generation Hybrid Image-Coding Techniques, M. Reha Civanlar, Sarah A. Rajala, Wonrae M. Lee
Sarah A. Rajala
Recently, ways to obtain a new generation of image-coding techniques have been proposed. The incorpordtion of the human visual system (IIVS) models and tools of the image analysis, such as segmentation, are two defining features of these techniques. In this paper, an application of the new approach to the classical linear predictive coding (LPC) of images and an HVS based segmentation technique for the second genera-tion coders will be discussed. In the case of LPC, the error image is encoded using an image decomposition approach and binary image coding. This improves the compression ratio keeping the quality nearly the same. …
Implementation Of A Projection Onto Convex Sets Iteration Based Image Coder, M. Reha Civanlar, Sarah A. Rajala, Thomas K. Miller
Implementation Of A Projection Onto Convex Sets Iteration Based Image Coder, M. Reha Civanlar, Sarah A. Rajala, Thomas K. Miller
Sarah A. Rajala
Projection onto convex sets iteration based image coding, where efficiently encodable sets are used to describe an image, is a recent approach to image compression. The technique allows the use of a variety of sets to encode an image. The focus of this paper, however, will be on two particular sets: the set of images whose cosine transform is known for certain frequencies and the set of images which are nonzero over a specified region. These sets can be used to encode interframe difference pictures of video teleconferencing images. A drawback of this new type of codec is its computational …
New Solution For Frequency And Pixel Domain Coding Using Convex Sets, Pete Santago, Sarah A. Rajala
New Solution For Frequency And Pixel Domain Coding Using Convex Sets, Pete Santago, Sarah A. Rajala
Sarah A. Rajala
This paper describes a new algorithm for combining spatial and frequency domain information about an image in order to improve coding. The algorithm utilizes successive projections onto two non-intersecting sets in order to determine the optimal frequency domain coefficients to transmit given some known spatial information. This technique is best suited to fixed block size transform coders and builds on the techniques used in previous work.
Technique For Video Compression By Projection Onto Convex Sets, P. Santago, Sarah A. Rajala
Technique For Video Compression By Projection Onto Convex Sets, P. Santago, Sarah A. Rajala
Sarah A. Rajala
This paper describes a video compression technique which utilizes the alternating projection theorem for convex sets. The image to be transmitted is determined to be in certain convex sets and parameters defining these sets are sent. The receiver can then use the method of successive projections to locate an image which is in the intersection of the sets. If the intersection is small then the image determined should be close to the desired image. The coder can be made more robust by easily adding additional convex sets or using it in conjunction with other coding schemes such as motion compensation.
An Evaluation Of The Directed Flow Graph Methodology, Wesley E. Snyder, Sarah A. Rajala
An Evaluation Of The Directed Flow Graph Methodology, Wesley E. Snyder, Sarah A. Rajala
Sarah A. Rajala
The purpose of this project was to evaluate the applicability of the Directed Graph Methodology (DGM) to the design and analysis of special purpose image and signal processing hardware. To this end, a special purpose image processing system was designed and described using DGM. The design, suitable for VLSI, implements an innovative region labeling technique. The utility of DGM was evaluated using this design.
Turbine Blade Image Processing System, Neal S. Page, Wesley E. Snyder, Sarah A. Rajala
Turbine Blade Image Processing System, Neal S. Page, Wesley E. Snyder, Sarah A. Rajala
Sarah A. Rajala
A vision system has been developed at North Carolina State University to identify the orientation and three dimensional location of steam turbine blades that are stacked in an industrial A-frame cart. The system uses a controlled light source for structured illumination and a single camera to extract the information required by the image processing software to calculate the position and orientation of a turbine blade in real time.