IMDSP-9.1

Lapped Directional Transform: A New Transform for Spectral Image Analysis
Dietmar Kunz (Philips Research Laboratories, Aachen, Germany), Til Aach (Medical University Luebeck, Germany)

We propose a new real-valued lapped transform for 2D-signal and image processing. Lapped transforms are particularly useful in block-based processing, since their intrinsically overlapping basis functions reduce or prevent block artifacts. Our transform is derived from the modulated lapped transform (MLT), which, as a real-valued and separable transform like the Discrete Cosine Transform, does not allow to unambiguously identify oriented structures from modulus spectra. This is in marked contrast to the (complex-valued) Discrete Fourier Transform (DFT). The new lapped transform is real-valued, and at the same time allows unambiguous detection of spatial orientation. Furthermore, a fast algorithm for this transform exists. As an application example, we investigate the transform's performance in spectral approaches to image restoration and enhancement in comparison to the DFT.

IMDSP-9.2

A Mathematical Description of the Dot Diffusion Algorithm in Image Halftoning, with application in Inverse Halftoning
Murat Mese, P. P Vaidyanathan (California Institute of Technology)

The dot diffusion method for digital halftoning has the advantage of parallelism unlike the error diffusion method. The method was recently improved by optimization of the so-called class matrix so that the resulting halftones are comparable to the error diffused halftones. In this paper, we will give a mathematical description of the dot diffusion method. This description is then applied in inverse halftoning.

IMDSP-9.3

FROM GAUSSIAN SCALE-SPACE TO B-SPLINE SCALE-SPACE
Yu-Ping Wang, Seng Luan Lee (Wavelets Strategic Research Programme, Department of Mathematics, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260)

The Gaussian kernel has long been used in the classical multiscale analysis. The purpose of the paper is to propose the uniform B-spline as an alternative for the visual modeling. A general framework for various scale-space representations is formulated using the B-spline approach. In particular, the evolution of the wavelet models can be well understood from such an approach. Most of the wavelet representations can be factored into B-spline bases and hence can be implemented efficiently using the spline technique. Besides, it is shown that the B-spline scale-space representations not only inherit most of the properties of the Gaussian scale-space but also have many advantages with respect to the efficiency, compactness and parallel structure.

IMDSP-9.4

A Genetic Algorithm Based Image Segmentation for Image Analysis
Miki Haseyama, Masateru Kumagai, Hideo Kitajima (School of Engineering, Hokkaido University)

In this paper a new genetic algorithm (GA) based image segmentation method is proposed for image analysis. This method using a mean square error (MSE) based criterion can segment an image into some regions, while estimating a suitable region representation. The criterion is defined as MSE caused by interpolating each region of an observed image with a parametric model. Since the criterion is expressed with not only the parameters of the model but also shape and location of the regions, the criterion can not be easily minimized by the usual optimization methods, the proposed method minimizes the criterion by a GA. The proposed method also includes a processor to eliminate fragile regions with the Markov random field (MRF) model. Though the thresholds of the existent methods negatively affect image segmentation results; since no thresholds are required in the proposed method, it segments images more accurately than the existent methods.

IMDSP-9.5

A Nonlinear Diffusion Equation as a Fast and Optimal Solver of Edge Detection Problems.
Ilya Pollak, Alan S Willsky (Massachusetts Institute of Technology), Hamid Krim (North Carolina State University)

A nonlinear diffusion process known to be effective for image segmentation is analyzed in 1-D. It is shown that it optimally solves certain edge detection problems. A fast implementation of the algorithm is introduced.

IMDSP-9.6

Automatic Index Creation for Handwritten Notes
Shingo Uchihashi, Lynn Wilcox (FX Palo Ato Laboratory, Inc.)

This paper describes a technique for automatically creating an index for handwritten notes captured as digital ink. No text recognition is performed. Rather, a dictionary of possible index terms is built by clustering groups of ink strokes corresponding roughly to words. Terms whose distribution varies significantly across note pages are selected for the index. An index page containing the index terms is created, and terms are hyper-linked back to their original location in the notes. Further, index terms occurring in a note page are highlighted to aid browsing.

IMDSP-9.7

Compensation of Partly Photographed Page-Images Using 3-D Shape Information
Toshifumi Nakajima, Masaaki Kashimura, Shinji Ozawa (Faculty of Science and Technology Department of Electrical Engineering, Keio University)

we propose a method in order to compensate page image distortion caused by photographing a book opened and placed on the stage just above. For compensating distortion 3D shape information of page is necessary to apply geometrical adjustments. To obtain much higher resolution pages need to be photographed partly, in this situation each neighboring image necessarily has overlap areas for joining together. we put characters exist in overlap area to good use for seeking of corresponding points in stereo method,3D shape information of book surface can be obtained. If the assumption that no change of the shape of page cross section along the binding are satisfied, satisfactory compensated images were obtained and joining them together was well performed.

IMDSP-9.8

Fast ad-hoc Inverse Halftoning using Adaptive Filtering
Oscar C Au (Hong Kong University of Science and Technology)

We propose a novel fast inverse halftoning technique using an adaptive spatial varying filtering. The proposed algorithm is significantly simpler than most existing algorithms while achieving a PSNR close to that of the set theoretic POCS.

IMDSP-9.9

Color Scanner Calibration via a Neural Network
Michael J Vrhel (Color Savvy Systems Limited), H J Trussell (North Carolina State University)

The mathematical formulation of calibrating color scanners is presented. The mapping from scanned values to colorimetric values is inherently nonlinear. Calibration required approximating this nonlinear mapping. Neural networks are particularly suited to this task. Performance using an artificial neural network generated LUT is compared to that achieved by other commonly used methods.

IMDSP-9.10

Circularly Symmetric Watermark Embedding in 2-D DFT Domain
Vassilios Solachidis, Ioannis Pitas (University of Thessaloniki)

This paper presents an algorithm for rotation and scale invariant watermarking of digital images. An invisible mark is embedded in magnitude of the DFT domain. It is robust in compression, filtering, cropping, translation and in small rotation. The watermark introduces image changes that are invisible to the human eye. The detection algorithm does not require the original image.

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Last Update: February 4, 1999 Ingo Höntsch