Diagonal Edges Research Articles

Efficient all path score computations on grid graphs

We study the Integer-weighted Grid All Paths Scores (IGAPS) problem, which is given a grid graph, to compute the maximum weights of paths between every pair of a vertex on the first row of the graph and a vertex on the last row of the graph. We also consider a variant of this problem, periodic IGAPS, where the input grid graph is periodic and infinite. For these problems, we consider both the general (dense) and the sparse cases.For the sparse periodic IGAPS problem with 0–1 weights, we give an O(rlog3(n2/r)) time algorithm, where r is the number of (diagonal) edges of weight 1. Our result improves upon the previous O(nr) result by Krusche and Tiskin for this problem.For the periodic IGAPS problem we give an O(Cn2) time algorithm, where C is the maximum weight of an edge. This improves upon the previous O(C2n2) algorithm of Tiskin. We also show a reduction from periodic IGAPS to IGAPS. This reduction yields o(n2) algorithms for this problem.

Constant-Hue-Based Color Filter Array Demosaicking Sensor for Digital Still Camera Implementation

In this paper, we propose an edge-oriented constant-hue scheme for a color filter array demosaicking sensor to reduce costs and the complexity of the digital camera system. Most digital still cameras use color filter arrays to sample the scenery. The image information needs proper interpolation to present a complete image. This paper proposes a novel design for color image interpolation to improve the result of such processing without great hardware and processing cost. The edge-oriented scheme and constant-hue interpolation are performed to process diagonal edge information. Experimental results show that our algorithm only adds some exquisite comparison function and provides a fine image quality. It is easy to implement in hardware design by simple operation.

해양 환경에서 웨이블렛 변환을 이용한 크기 변화에 무관한 물표 탐지 알고리즘

In this paper, we propose an algorithm to detect scale invariant object from IR image obtained in the sea environment. We create horizontal edge (HL), vertical edge (LH), diagonal edge (HH) of images through 2-D discrete Haar wavelet transform (DHWT) technique after noise reduction using morphology operations. Considering the sea environment, Gaussian blurring to the horizontal and vertical edge images at each level of wavelet is performed and then saliency map is generated by multiplying the blurred horizontal and vertical edges and combining into one image. Then we extract object candidate region by performing a binarization to saliency map. A small area in the object candidate region are removed to produce final result. Experiment results show the feasibility of the proposed algorithm.

Effective technique for the recognition of offline Arabic handwritten words using hidden Markov models

In this paper, we present a novel segmentation-free Arabic handwriting recognition system based on hidden Markov model (HMM). Two main contributions are introduced: a new technique for dividing the image into nonuniform horizontal segments to extract the features and a new technique for solving the problems of the skewing of characters by fusing multiple HMMs. Moreover, two enhancements are introduced: the pre-processing method and feature extraction using concavity space. The proposed system first pre-processes the input image by setting the thickness of the input word to three pixels and fixing the spacing between the different parts of the word. The input image is divided into constant number of nonuniform horizontal segments depending on the distribution of the foreground pixels. A set of robust features representing the gradient of the foreground pixels is extracted using sliding windows. The input image is decomposed into several images representing the vertical, horizontal, left diagonal and right diagonal edges in the image. A set of robust features representing the densities of the foreground pixels in the various edge images is extracted using sliding windows. The proposed system builds character HMM models and learns word HMM models using embedded training. Besides the vertical sliding window, two slanted sliding windows are used to extract the features. Three different HMMs are used: one for the vertical sliding window and two for the slanted windows. A fusion scheme is used to combine the three HMMs. The proposed system is very promising and outperforms all the other Arabic handwriting recognition systems reported in the literature.

Text Extraction of Colour Images using Mathematical Morphology & HAAR Transform

Digital image processing is an ever expanding and dynamic area with applications reaching out into our daily life such as digital signature, authentication, surveillance, medicine, space exploration, automated industry inspection and many others areas. Theseapplications are involved in different processes like image enhancement, object detection, features extraction, colour imaging etc. Implementation of such applications on a general purpose computer can be easier, but every time it is not efficient due to additional constraints on memory and other peripheral devices. Out of the five senses - sight, hearing, touch, smell and taste, humans use to perceive their environment. Among all,sight of images is the most powerful. More than 99% of the activity of the human brain is involved in processing images from the visual cortex. A visual image is rich in information. There is an efficient yet simple method to extract text regions from video sequences or static images. The speed of Haar discrete wavelet transform (DWT) operates the fastest among all wavelets because its coefficients are either 1 or -1. It is one of the reasons that Haar DWT is used to detect edges of candidate text regions. Image sub bands contain both text edges and non-text edges. The intensity of the text edges is also different from that of the non-text edges. Therefore, thresholdingis used to preliminary remove the non-text edges. Text regions of colour images are composed of horizontal edges, vertical edges and diagonal edges. Morphological dilation operators as AND, OR are applied to connect isolated text edges of each detail component sub-band in a transformed binary image. The simulation is carried out on MATLAB 2012 image processing tool.

Image pattern recognition technique for the classification of multiple power quality disturbances

In a practical power system, a power quality (PQ) event often consists of various types of disturbances occurring at the same time. However, most of the existing techniques are trained to classify single disturbances, and hence have very limited usage in classifying real-time data. This work proposes a novel technique to automatically detect and classify multiple disturbances that coexist in PQ monitoring data. The data obtained from PQ monitors are represented in the form of 2-dimensional (2D) images. This 2D data visualization has significant benefits, in that each type of disturbance produces a different type of edge in the image; a sag produces horizontal edges, an oscillatory transient diagonal edges, and so on. The 2D discrete wavelet transform is applied to decompose these 2D images into 4 subbands using the Haar wavelet transform. Each of the events constituting the multiple disturbances has its own signature in each of the subbands and these signatures aid in the detection of these events. Pertinent features extracted from the wavelet subbands are utilized to train decision trees. These decision trees describe the rules needed for multiple event classification. Comparison results with the S-transform classification technique indicate that the proposed technique can offer faster classification and comparable accuracy, not only for a single disturbance, but also for multiple ones. Nevertheless, its memory requirement is very meager compared to S-transform. Moreover, it performs better than 1D wavelet-based event detection and classification techniques.

On the noncommutative geometry of square superpotential algebras

A superpotential algebra is square if its quiver admits an embedding into a two-torus such that the image of its underlying graph is a square grid, possibly with diagonal edges in the unit squares; examples are provided by dimer models in physics. Such an embedding reveals much of the algebras representation theory through a device we introduce called an impression. Let A be a square superpotential algebra, Z its center, and m the maximal ideal at the origin of SpecZ. Using an impression, we•give a classification of all simple A-modules up to isomorphism, and give algebraic and homological characterizations of the simple A-modules of maximal k-dimension;•show that Z is a 3-dimensional normal toric domain and Zm is Gorenstein, by determining transcendence bases and Z-regular sequences; and•show that Am is a noncommutative crepant resolution of Zm, and thus a local Calabi–Yau algebra.A particular class of square superpotential algebras, the Yp,q algebras, is considered in detail. We show that the Azumaya and smooth loci of the centers coincide, and propose that each ramified maximal ideal sitting over the singular locus is the exceptional locus of a blowup shrunk to zero size.

A Compact UWB Microstrip Antenna with Modified Ground Plane for Bandwidth Enhancement

This paper presents a bandwidth enhancing technique using a modified ground plane with diagonal edges, L-shaped slot and parasitic patches with main patch for the design of compact antennas. The proposed low-cost, compact-size rectangular patch antenna on 4.7 cm × 3.6 cm printed circuit board (FR-4) is designed and validated through simulations and experiments. Results show that the ground plane with Lshaped slot in presence of the diagonal cuts at the top corners and the rectangular parasitic patches can increase the bandwidth. Return losses of −23.6 dB and −29.7 dB for the first and second resonant frequencies, respectively, can be achieved when the depth of the diagonal cut is 3 mm, the dimension of each rectangular parasitic patch is 10 mm×3.5 mm, and the L-shaped slot size is 7.5 mm ×2.5mm, providing a 41.27% wider bandwidth than Federal Communication Commission’s(FCC) standard. General Terms Designing of Microstrip Antenna.

Face Recognition using Geometric Measurements, Directional Edges and Directional Multiresolution Information

This paper propose the extraction of geometric measurements of face regions, different directional information and multiscale information offered by real tree dual discrete wavelet transform to generate facial features for face recognition. The proposed scheme calculates feature sets: geometric measurements such as the area measures of eye, nose and mouth, horizontal, vertical, and diagonal directional edge information and multiscale information using whole face information. Existing feature-based or local features based methods, depends on characterization of individual facial features (i.e., eyes, nose, and mouth etc.) and their geometrical relationships. Our approach automatically calculates the measures of important areas of interest that describe the information present in an individual face image. The area of different segmented regions is calculated that describes the information of facial components. The proposed geometric features, directional information using Fast Wavelet transform and multiscale image formation gives the rotation, pose and expression invariant face recognition. Fusion of various generated features improves the recognition considering the different segmented face information. The success of the scheme is the automatic calculation of various geometric features, directional edge information and whole face information. The main features of our approach are detection of important regions, calculation of geometric features and fusion with information offered by edge and multiscale information. We demonstrate the success of our approach by experiments.

Similarity-based demosaicing algorithm using unified high-frequency map

This paper introduces an innovative demosaicing algorithm for color filter array (CFA). Conventional demosaicing algorithms usually detect edges in horizontal-, vertical- or omni-direction, and apply a directional filtering along the edge direction. It is found that these algorithms do not properly work for diagonal edges. We, then, invent a similarity based filtering using unified high-frequency (UHF) map. This new technique enables flexible filtering masks so as to be able to deal with edges of any direction. It is confirmed through experiments that the proposed algorithm outperforms state-of-the-art algorithms in terms of PSNR and subjective quality. In addition, the proposed algorithm requires fewer resources than the state-of-the-art algorithms.

Physical and dosimetric characteristic of high‐definition multileaf collimator (HDMLC) for SRS and IMRT

Physical and dosimetric characteristics of HDMLC were studied for SRS6, 6, and 10 MV X‐rays from Novalis Tx. This in‐built tertiary collimator consists of 60 pairs (32×0.25 cm; 26×0.5 cm and 2×0.7 cm) of leaves. Properties of HDMLC studied included alignment, readout and radiation field congruence, radiation penumbra, accuracy and reproducibility of leaf position and gap width, static and dynamic leaf shift, tongue‐and‐groove effect, leaf transmission and leakage, leaf travel speed, and delivery of dynamic conformal arc and IMRT. All tests were performed using a calibrated ionization chamber, film dosimetry and DynaLog file analysis. Alignment of leaves with isocenter plane was better than 0.03 cm at all gantry and collimator positions. The congruence of HDMLC readout and radiation field agreed to within ± 0.03cm for filed sizes ranging from 1×1 to 20×20 cm2. Mean 80% to 20% penumbra width parallel (perpendicular) to leaf motion was 0.24±0.05(0.21±0.02) cm, 0.37±0.12(0.29±0.07) cm, and 0.51±0.13(0.43±0.07) cm for SRS6, 6, and 10 MV X‐rays, respectively. Circular field penumbra was comparable to corresponding square field. Average penumbra of 1×20 cm2 field was effectively constant over off‐axis positions of up to 12 cm with mean value of 0.16 (± 0.01)cm at 1.5 cm depth and 0.38 (± 0.04)cm at 10 cm depth. Minimum and maximum effective penumbra along the straight diagonal edge of irregular fields increased from 0.3 and 0.32 cm at 70° steep angle to 0.35 and 0.56 cm at 20° steep angle. Modified Picket Fence test showed average FWHM of 0.18 cm and peak‐to‐peak distance of 1.99 cm for 0.1 cm band and 2 cm interband separation. Dynamic multileaf collimation (DMLC) output factor remained within ± 1% for 6 MV and ± 0.5% for 10 MV X‐rays at all gantry positions, and was reproducible within ± 0.5% over a period of 14 months. The static leaf shift was 0.03 cm for all energies, while dynamic leaf shift was 0.044 cm for 10 MV and 0.039 cm for both SRS6 and 6 MV X‐rays. The dose depression and corresponding tongue‐and‐groove size were 24% and 0.17 cm for 6 MV and 19% and 0.20 cm for 10 MV X‐rays. Average transmission through HDMLC was 1.09%, 1.14% and 1.34% for SRS6, 6 and 10 MV X‐rays. Analysis of DynaLog files for leaf speed test in arc dynamic mode, delivery test of dynamic conformal arc, and step‐and‐shoot and sliding window IMRT showed at least 95% or more of the error counts had misplacements < 0.2cm, with maximum root mean square (RMS) error value calculated at 0.13 cm. Accurate and reproducible leaf position and gap width, and less leakage and small consistent penumbra over the fields demonstrate HDMLC suitable for high‐dose resolution SRS and IMRT.PACS number: 87.56.N‐, 87.55.Qr, 87.50.cm, 87.55.de, 87.53.Ly

A novel steganalysis for TPVD steganographic method based on differences of pixel difference histogram

Tri-way Pixel Value Differencing (TPVD) steganographic method is a new modified version of another well-known method called PVD, which intents to increase embedding capacity and security of its successor by hiding secret bits in both vertical and diagonal edges of a cover image, in addition to the horizontal edges used in PVD. In this paper, it is shown that the histogram of difference values of a stego image under the TPVD algorithms is vulnerable to a particular statistical analysis. So, a new steganalytic measure named Growing Anomalies is introduced that its value has a linear relationship with secret message rate. It is shown empirically and theoretically that proposed steganalysis method based on this measure can estimate the amount of secret bits with a negligible error rate. The proposed steganalyser can classify test images as stego or cover with 97% accuracy when they contain more that 10% secret data. Implementation results indicate that proposed method can estimate secret message rate with an average accuracy of 95%.

Study on a Real-Time Corner Detection Algorithm

Conventional Harris corner detector is a desirable detector but it requires significantly more computation time. For MIC detector proposed by Trajkovic, the minimal computational demands of its operator make it well-suited for real-time applications, however the Trajkovic’s operator responses too readily to certain diagonal edges. For this reason, the paper proposed a new corner detection algorithm. The new corner detection algorithm adopted multigrid algorithm and preprocessed the lower resolution revision of the original image to obtain the potential corners, subsequently used autocorrelation matrix to get the corner response function for the corresponding points of the potential corner. The test results indicate the new corner detection algorithm can decrease edge responses and the number of textural corners effectively. Furthermore, it can satisfy the demands of real-time applications.

The energy of a type of lattice

The energy of a simple graph G , denoted by E ( G ) , is defined as the sum of the absolute values of eigenvalues of G . Let G f ( m , n ) (resp., G c ( m , n ) and G t ( m , n ) ) be the lattice obtained from an m × n square lattice with free boundary condition (resp., cylindrical boundary condition and the toroidal boundary condition) by adding two diagonal edges to each square. In this work, we obtain the formulae for the energies of G f ( m , n ) , G c ( m , n ) , and G t ( m , n ) . The asymptotic energies of G f ( m , n ) , G c ( m , n ) and G t ( m , n ) are also given.

방향성 필터를 이용하여 대각선 에지를 고려한 Demosaicing 알고리즘 및 하드웨어 구현

대부분의 디지털 촬영 장치는 비용 및 속도 상의 이점을 위해 Color Filter Array(CFA)를 포함하고 있는 단일 이미지 센서를 사용한다. 따라서 완전한 컬러 영상으로 복원하기 위하여 다양한 컬러 보간 방법이 개발되고 있다. 본 논문은 이러한 컬러 보간 방법 중, 방향성 필터를 이용하여 수직, 수평, 대각선 방향의 에지를 고려한 컬러 보간 방법에 관한 것이다. 하드웨어 구현을 위해 하드웨어 자원의 효율성을 고려하였다. Kodak 테스트 영상 24장으로 실험하여 기존 방법과 비교함으로써 제안한 방법의 성능을 확인하였다. Verilog HDL로 구현하였으며, Virtex4 FPGA 보드와 CMOS 이미지 센서를 이용하여 검증하였다. Most digital cameras use a single image sensor with Color Filter Array(CFA) for the advantage of costs and speed. The various color interpolation(demosaicing) algorithms are researched to reconstruct a full representation of the image. In this paper, we proposed a method of demosaicing about using weighted directional filter for vertical, horizontal, and diagonal direction edge. The method considered the efficiency of hardware resources for hardware implementation. The performance of proposed method was confirmed by comparing the conventional method in experiments using 24 Kodak test images. The proposed method was designed by Verilog HDL and was verified by using Virtex4 FPGA boards and CMOS Image Sensor.

Medical ultrasound image denoising based on improved anisotropic diffusion equation

An improved method based on anisotropic diffusion equation was proposed. By expanding the Perona and Malik anisotropic diffusion model (P-M model) to include diagonal edges,more image details were added. And a new approach of calculating the diffusion coefficient overcame the high rate of convergence;the novel gradient operator could distinguish noise points and detect edge. The simulation results show that the performance of the method is superior to the classical P-M equation and Linshi operator in image smoothing and edge preserving,as well as the reduction of iteration time. The method is an effective way of suppressing speckle noise in ultrasound images.

A spectral characterization of the Delaunay triangulation

The Delaunay triangulation of a planar point set is a fundamental construct in computational geometry. A simple algorithm to generate it is based on flips of diagonal edges in convex quads. We characterize the effect of a single edge flip in a triangulation on the geometric Laplacian of the triangulation, which leads to a simpler and shorter proof of a theorem of Rippa that the Dirichlet energy of any piecewise-linear scalar function on a triangulation obtains its minimum on the Delaunay triangulation. Using Rippa's theorem, we provide a spectral characterization of the Delaunay triangulation, namely that the spectrum of the geometric Laplacian is minimized on this triangulation. This spectral theorem then leads to a simpler proof of a theorem of Musin that the harmonic index also obtains its minimum on the Delaunay triangulation.

Bandwidth Enhancement of UWB Microstrip Antenna with a Modified Ground Plane

This article presents a bandwidth enhancing technique using a modified ground plane with diagonal edges, rectangular slot, and T-shape cut for the design of compact antennas. The proposed low-cost, compact-size circular patch antenna on 3 cm 5.1 cm printed circuit board (FR-4) is designed and validated through simulations and experiments. Results show that the T-shaped ground plane with the presence of the diagonal cuts at the top corners and the rectangular slots can increase the bandwidth. Return losses of 19 and 26 dB for the first and second resonant frequencies, respectively, can be achieved when the depth of the diagonal cut is 5 mm, the dimension of each rectangular slot is mm, and the T-shaped size is mm, providing a 28.67% wider bandwidth than FCC standard.

Bandwidth Increasing Technique Using Modified Ground Plane with Diagonal Edges

This paper presents a bandwidth increasing technique using a modified ground plane with diagonal edges for the design of compact antennas. The proposed low-cost, compact-size circular patch antenna on 3 cm × 5.1 cm printed circuit board (FR-4) is designed and validated through simulations and experiments. Results show that with diagonal cuts at corners of the ground plane, the enhanced bandwidth can be tunable depending on the removed area. Return losses of minus 17 and minus 30 dBs for the first and second resonant frequencies, respectively, can be achieved when the depth of the diagonal cut is at optimum value of five mm, providing an 18.13% wider bandwidth (2.95–12.615 GHz) than the Federal Communication Commission (FCC) standard.

Adaptive blocking artifact reduction using wavelet-based block analysis

In this paper a signal adaptive postprocessing algorithm is presented to remove visually annoying blocking artifacts in BDCT-coded images. The wavelet-based block analysis is adopted to exploit the directional activity of each block, as a systematic approach in decision of the block type. The proposed 1D filters that are applied activity-adaptively alleviate grid noises effectively and a directional 2D filter reduces staircase noises and corner outliers near diagonal edges while preserving original details. Comprehensive experiments indicate that the proposed algorithm outperforms a number of deblocking methods in the literature in terms of PSNR and subjective visual quality. Moreover, the proposed algorithm takes less run time than those of the conventional methods, and thus it can be used in real-time applications for moving pictures as well as still images.