Engineering Commons^™

The Applications Of Grid Cells In Computer Vision, Keaton Kraiger

Undergraduate Research & Mentoring Program

In this study we present a novel method for position and scale invariant object representation based on a biologically-inspired framework. Grid cells are neurons in the entorhinal cortex whose multiple firing locations form a periodic triangular array, tiling the surface of an animal’s environment. We propose a model for simple object representation that maintains position and scale invariance, in which grid maps capture the fundamental structure and features of an object. The model provides a mechanism for identifying feature locations in a Cartesian plane and vectors between object features encoded by grid cells. It is shown that key object features …

Good Similar Patches For Image Denoising (Poster), Si Lu

Computer Science Faculty Publications and Presentations

Patch-based denoising algorithms like BM3D have achieved outstanding performance. An important idea for the success of these methods is to exploit the recurrence of similar patches in an input image to estimate the underlying image structures....

Video Frame Interpolation Via Adaptive Convolution, Simon Niklaus, Long Mai, Feng Liu

Computer Science Faculty Publications and Presentations

Video frame interpolation typically involves two steps: motion estimation and pixel synthesis. Such a two-step approach heavily depends on the quality of motion estimation. This paper presents a robust video frame interpolation method that combines these two steps into a single process. Specifically, our method considers pixel synthesis for the interpolated frame as local convolution over two input frames. The convolution kernel captures both the local motion between the input frames and the coefficients for pixel synthesis. Our method employs a deep fully convolu- tional neural network to estimate a spatially-adaptive con- volution kernel for each pixel. This deep neural …

Quantitative Carré Differential Interference Contrast Microscopy To Assess Phase And Amplitude, Donald D. Duncan, David G. Fischer, Amanda Dayton, Scott A. Prahl

Electrical and Computer Engineering Faculty Publications and Presentations

We present a method of using an unmodified differential interference contrast microscope to acquire quantitative information on scatter and absorption of thin tissue samples. A simple calibration process is discussed that uses a standard optical wedge. Subsequently, we present a phase-stepping procedure for acquiring phase gradient information exclusive of absorption effects. The procedure results in two-dimensional maps of the local angular (polar and azimuthal) ray deviation. We demonstrate the calibration process, discuss details of the phase-stepping algorithm, and present representative results for a porcine skin sample.

Experimental Observations Of Active Invariance Striations In A Tank Environment, Jorge E. Quijano, Richard L. Campbell, Tobias G. Oesterlein, Lisa M. Zurk

Electrical and Computer Engineering Faculty Publications and Presentations

The waveguide invariant in shallow water environments has been widely studied in the context of passive sonar. The invariant provides a relationship between the frequency content of a moving broadband source and the distance to the receiver, and this relationship is not strongly affected by small perturbations in environment parameters such as sound speed or bottom features. Recent experiments in shallow water suggest that a similar range-frequency structure manifested as striations in the spectrogram exists for active sonar, and this property has the potential to enhance the performance of target tracking algorithms. Nevertheless, field experiments with active sonar have not …

Computer-Aided Assessment Of Diagnostic Images For Epidemiological Research, Alison G. Abraham, Donald D. Duncan, Stephen J. Gange, Sheila West

Electrical and Computer Engineering Faculty Publications and Presentations

Background: Diagnostic images are often assessed for clinical outcomes using subjective methods, which are limited by the skill of the reviewer. Computer-aided diagnosis (CAD) algorithms that assist reviewers in their decisions concerning outcomes have been developed to increase sensitivity and specificity in the clinical setting. However, these systems have not been well utilized in research settings to improve the measurement of clinical endpoints. Reductions in bias through their use could have important implications for etiologic research. Methods: Using the example of cortical cataract detection, we developed an algorithm for assisting a reviewer in evaluating digital images for the presence and …

Measurement Of Oxygen Saturation In The Retina With A Spectroscopic Sensitive Multi Aperture Camera, Jessica C. Ramella-Roman, Scott A. Mathews, Haripriya Kandimalla, Afshin Nabili, Donald D. Duncan, Salvatore A. D'Anna, Syed M. Shah, Quan D. Nguyen

Electrical and Computer Engineering Faculty Publications and Presentations

We introduce a new multi aperture system capable of capturing six identical images of the human fundus at six different spectral bands. The system is based on a lenslet array architecture and is well suited for spectroscopy application. The multi-aperture system was interfaced with a fundus camera to acquire spectroscopic sensitive images of the retina vessel and ultimately to calculate oxygen saturation in the retina in vivo. In vitro testing showed that the system is able to accurately reconstruct curves of partially oxygenated hemoglobin. In vivo testing on healthy volunteers was conducted and yielded results of oxygen saturation similar to …

Non-Laser-Based Scanner For Three-Dimensional Digitization Of Historical Artifacts, Donald D. Duncan, Daniel V. Hahn, Kevin C. Baldwin

Electrical and Computer Engineering Faculty Publications and Presentations

A 3D scanner, based on incoherent illumination techniques, and associated data-processing algorithms are presented that can be used to scan objects at lateral resolutions ranging from 5 to 100 m (or more) and depth resolutions of approximately 2 m. The scanner was designed with the specific intent to scan cuneiform tablets but can be utilized for other applications. Photometric stereo techniques are used to obtain both a surface normal map and a parameterized model of the object’s bidirectional reflectance distribution function. The normal map is combined with height information, gathered by structured light techniques, to form a consistent 3D surface. …

A Simplified Approach To Reduce Blocking And Ringing Artifacts In Transform-Coded Images, Jianping Hu

Dissertations and Theses

Presently Block-based Discrete Cosine Transform (BDCT) image coding techniques are widely used in image and video compression applications such as JPEG and MPEG. At a moderate bit rate, BDCT is usually a quite satisfactory solution to most of practical coding applications. However, for high rate compression it produces noticeable blocking and ringing artifacts in the decompressed image. It has been an active research area for a decade for reducing these artifacts. In this thesis, a novel post-processing algorithm is proposed to remove the blocking and ringing artifacts at low bit rate. It is non-iterative and uses both spatial and transform …

Developing Image Processing Tools In X Window System, Xin Zhang

Dissertations and Theses

The X Window System is an industry-standard software system which facilitates programmers to develop portable graphical user interfaces. This thesis describes an image processing tool developed under the X Window System. A multiwindow image display software with image editing and improvement functions is developed. The software has four modules: environment generation, image creation, image editing and image improvement.

The environment generation module creates working windows, scrollbars, dialogbox and pulldown menu buttons, and tracks mouse cursor positions. The working windows are three adjacent windows allowing display of three different images simultaneously. The dialogbox provides an interface between the user and the …

Low To Medium Level Image Processing For A Mobile Robot, Cecilia H. Espinosa

Dissertations and Theses

The use of visual perception in autonomous mobile systems was approached with caution by mobile robot developers because of the high computational cost and huge memory requirements of most image processing operations. When used, the image processing is implemented on multiprocessors or complex and expensive systems, thereby requiring the robot to be wired or radio controlled from the computer system base.

Decomposition Of Measured Contours Into Geometric Features For Dimensional Inspection, Devaraj Rajkumar

Dissertations and Theses

Image processing systems used in Vision Assisted Dimensional Inspection usually output a set of boundary pixels representing the part edges. This boundary information must be divided into several subsets representing the various edges of the actual object, so that comparisons with the nominal part can be made.

The purpose of this project is to devise a method to divide the set of pixels obtained from the image processing system into subsets of pixels. Each of these subsets represent an edge in the contour of the actual object. This method must also detect transition points between the adjacent features. This project …

A Comparative Study Of The Performance Of Various Image Analysis Methods For Dimensional Inspection With Vision Systems, Ralf Heinrich Koeppe

Dissertations and Theses

Dimensional inspection with Vision Systems requires a careful selection of image analysis methods in order to obtain accurate information about the geometry of the parts to be measured.

The purpose of this project is to study, implement and compare different image evaluation methods and to show their strengths and weaknesses with respect to dimensional inspection. Emphasis is made on the inspection of circular features. The criteria of comparison for these methods are discussed. Using synthetically generated images, various analysis methods are compared and conclusions for their use are drawn. Results of the comparison show that the selection of a method …

Invariant Pattern Recognition Algorithm Using The Hough Transform, Duwang Li

Dissertations and Theses

A new algorithm is proposed which uses the Hough Transform to recognize two dimensional objects independent of their orientations, sizes and locations. The binary image of an object is represented by a set of straight lines. Features of the straight lines, namely the lengths and the angles of their normals, their lengths and the end point positions are extracted using the Hough Transform. A data structure for the extracted lines is constructed so that it is efficient to match the features of the lines of one object to those of another object, and determine if one object is a rotated …

Parallel Approximate String Matching Applied To Occluded Object Recognition, David Smith

Dissertations and Theses

This thesis develops an algorithm for approximate string matching and applies it to the problem of partially occluded object recognition. The algorithm measures the similarity of differing strings by scanning for matching substrings between strings. The length and number of matching substrings determines the amount of similarity. A classification algorithm is developed using the approximate string matching algorithm for the identification and classification of objects. A previously developed method of shape description is used for object representation.

Quadtree-Based Processing Of Digital Images, Ramin Naderi

Dissertations and Theses

Image representation plays an important role in image processing applications, which usually. contain a huge amount of data. An image is a two-dimensional array of points, and each point contains information (eg: color). A 1024 by 1024 pixel image occupies 1 mega byte of space in the main memory. In actual circumstances 2 to 3 mega bytes of space are needed to facilitate the various image processing tasks. Large amounts of secondary memory are also required to hold various data sets.

In this thesis, two different operations on the quadtree are presented.

There are, in general, two types of data …

Two New Parallel Processors For Real Time Classification Of 3-D Moving Objects And Quad Tree Generation, Farjam Majd

Dissertations and Theses

Two related image processing problems are addressed in this thesis. First, the problem of identification of 3-D objects in real time is explored. An algorithm to solve this problem and a hardware system for parallel implementation of this algorithm are proposed. The classification scheme is based on the "Invariant Numerical Shape Modeling" (INSM) algorithm originally developed for 2-D pattern recognition such as alphanumeric characters. This algorithm is then extended to 3-D and is used for general 3-D object identification. The hardware system is an SIMD parallel processor, designed in bit slice fashion for expandability. It consists of a library of …