This PDF file contains the editorial “Reading in the 21st Century” for OE Vol. 45 Issue 04

An experimental system for liquid concentration measurement was set up based on the optoacoustic effect and a fiber Bragg grating (FBG) underwater sound sensor. Measurement theory and each element of the experimental setup are introduced. The light beam was injected into the liquid by a fiber bundle with a graded-refractive-index lens at the end. A matched FBG was used to demodulate the wavelength shift signals from the sensing FBG. Preliminary experimental results of sodium carbonate liquid concentration measurement were obtained, which verifies the feasibility of the method.

Planar diffractive optical interconnects have many advantages, however, their inherent chromaticity leads to temperature instability due to the wavelength shift of laser diodes' radiation. This shift can be compensated if the optical interconnect is bended in an appropriate direction with curvature proportional to the relative wavelength shift. The bending can be performed by attaching an additional plate to the element with a different thermal expansion coefficient. Theoretical analysis and ray tracing are reported.

We experimentally investigate the influence of vestigial sideband (VSB) filtering in a 40-Gbit/s optical system. Two kinds of optical filters and different pseudorandom bit sequences (PRBS) are used in experiment. The results show that optical filter ramp and PRBS length will cause different impacts in a VSB carrier suppressed return-to-zero system.

Scanning fiber optical endoscopy shows promise as a small, inexpensive imaging tool. Using this method of image acquisition, a scanning fiber is actuated at mechanical resonance, projecting a light spot across an imaged surface. Light backscattered from scanned spots is measured to form an image. The acquired image field of view, resolvable pixels, and frame rate are dependent on the dynamics of the optical fiber used as a resonant scanner. A finite-element analysis (FEA) model was constructed to predict scanning fiber dynamics, and compared with experimental results. A scanning fiber microfabrication process was developed that allows for the controlled manufacture of fiber scanners. Experimental results confirm that the theoretical model was accurate in predicting the system transfer function with less than 6% error in amplitude and less than 10% error in resonant frequency at the first two resonant modes of a cylindrical and a microfabricated fiber. The scanning fiber microfabrication process proved to be capable of repeatably etching notches in optical fibers as small as 2.00±0.05 mm in length and 15±2 µm in diameter. FEA was used to predict the effect of geometry change on microfabricated fiber scan dynamics, yielding candidate designs chosen for enhanced performance of future scanning endoscopes.

Ray tracing is used to design two-dimensional lens ducts with maximum transfer efficiency for specified parameters. Diode efficiency and ray efficiency are introduced in order to study transmission of rays through the lens duct. Calculation shows that the transfer efficiency depends on the lens duct parameters and the divergence of the input ray. With high-performance antireflection coating on the exit aperture of the lens duct, diode transfer efficiency as large as 99% is obtained for the slow axis of the laser diode.

A heterodyne optical head of a phase-shift laser range finder has been developed to measure distances with high accuracy. To increase the signal-to-noise ratio of the photoelectric current, an avalanche photodiode (APD) working as an optoelectronic mixer was used. A new behavioral model is proposed to describe the optical head in order to evaluate its performance according to the background light intensity. When the APD is biased with a dc current source, it is then demonstrated that the signal-to-noise ratio of the signal at the intermediate frequency, as well as the conversion gain, is inversely proportional to the average primary photoelectric current, i.e., to the background light collected by the APD. Yet, the performance obtained can be improved by using an optical filter. Furthermore, the background light also introduces a phase-shift error, which is evaluated so as to estimate the distance error.

We describe the rigorous results of a wide-angle laser beam scanner, obtained with the help of the vector refraction theory. Using the rigorous results, the distortion of the beam shape is discussed. The distortion to the beam varies with the different relative angles of double prisms. The scanner expands the beam in some directions while it contracts the beam in other directions. According to the conservation of energy, the distribution of the laser intensity is changed as well.

Due to the need of a highly sensitive touch keyboard for the disabled, we propose no-moving-parts optical touch keyboard architectures based on the use of light splitting and blocking concepts. Light splitting via a fiber optic splitter is also introduced to reduce the precise optical alignment technique required in our free-space-based optical touch keyboard. Several key features are accomplished, including high switch sensitivity, scalability, ease of implementation, and low electrical power consumption. Our free-space-based 5×4 optical touch keyboard prototype shows a key activating time of 19 ms for a keyboard scanning rate of 180 ms per 20 keys. Our optical touch keyboard prototype is also tested in more than 4000 key operations under environmental illuminations from a typical 400 lux to a high 3000 lux without keyboard failure, thus promising good use in practice.

In this investigation, an optical system is introduced for inspecting the interiors of confined spaces, such as the walls of containers, cavities, reservoirs, fuel tanks, pipelines, and the gastrointestinal tract. The optical system wirelessly transmits stereoscopic video to a computer that displays the video in realtime on the screen, where it is viewed with shutter glasses. To minimize space requirements, the videos from the two cameras (required to produce stereoscopic images) are multiplexed into a single stream for transmission. The video is demultiplexed inside the computer, corrected for fisheye distortion and lens misalignment, and cropped to the proper size. Algorithms are developed that enable the system to perform these tasks. A proof-of-concept device is constructed that demonstrates the operation and the practicality of the optical system. Using this device, tests are performed assessing validities of the concepts and the algorithms.

Smooth patterns were written into PMGI electron-beam resist using electron-beam lithography on BK7 blank concave mirror substrates, resulting in aspheric optics with sag as large as 4 µm. Interference microscope measurements revealed that the fabricated optics had height accuracy of 10 nm. These optics were designed for flattop mode shaping in laser resonators. Excellent performance of these optics has been demonstrated by testing them as fixed phase-conjugate mirrors outside laser resonators, as well as mode-shaping mirrors within laser resonators.

We describe a process to fabricate an optical-quality grating using protein as the biomaterial building block. The resulting grating is capable of generating high-quality diffraction. We demonstrate how such a biograting has the potential for the detection of small amounts of unlabeled biological analyte.

The surface microroughness of paper has an important role on its gloss. Unfortunately, commercial glossmeters do not provide information on the local gloss of paper. In this study a low-coherence interferometer was employed for the assessment of the average surface roughness of fine, supercalendered, and Xerox papers by means of recorded topography maps. Furthermore, the local and average gloss were measured by a diffractive-optical-element-based glossmeter. This is the first time that the measurement of the local gloss of paper has been accomplished. The information on both surface roughness and gloss, obtained by the two devices in this study, should help papermakers in their research and development of optimal paper surface quality, which is crucial to optimal ink absorption in printing.

A new calibration method is proposed for calibrating cameras with large lens distortion, using a planar grid pattern. The distortions are adjusted with an iterative algorithm. When the points on each curve in the image of the grid pattern are fitted with a linear equation in the image space, the distortion correction factors are determined. The camera's optical center is obtained through a Hough transform. Then, a group of linear equations and a cubic equation are established in the corrected image space. The remaining parameters of the camera are then deduced. Only one view of a planar grid pattern is needed for this method. The experimental results verify the effectiveness of the proposed method.

A low-cost, compact electro-optical leveler, using a CMOS image sensor, has been developed for level measurement. The two-lens optical system is designed to find the tilt information for the total system. ZEMAX is used to design and predict the performance of this optical system. One lens is bowl-shaped so that it can hold a liquid. The centroid of the light spot on the CMOS image sensor is converted into pixel coordinates proportional to the tilt angle to be measured. The experimental results verified the simulation results. The reading tilt angle can be estimated with a resolution at better than 8 arcsec.

A two-dimensional small-rotation-angle measurement system based on fringe projection is proposed and demonstrated. Simple and effective signal processing is described and applied to the angular calculation. Several measurements indicate a measurement accuracy of ≈ 0.4 arcsec, which is comparable to that of a high-priced autocollimator. The two-dimensional two-pitch grating used in our prototype system provides a wide measurement range, which is expected to reach 1300 arcsec for both x- and y-direction rotations.

We describe an automated three-axis gonioreflectometer, which can help increase the physical realism of computer graphics renderings by providing light scattering data for the surfaces in a scene. The gonioreflectometer performs rapid measurements of the bidirectional reflectance distribution function (BRDF) for flat, isotropic, sample surfaces over the complete visible spectrum and over most of the incident and reflection hemispheres. The instrument employs a broadband light source and a detector with a diffraction grating and linear diode array. Validation is achieved by comparisons against reference surfaces and other instruments. The accuracy and spectral and angular ranges of the BRDFs are appropriate for computer graphics imagery, while reciprocity and energy conservation are preserved. Measured BRDFs on rough aluminum, metallic silver paint, and a glossy yellow paint are reported, and an example rendered automotive image is included.

A model of the spectral responsivity of In_1–χGa_χSb p-n junction infrared photodetectors is developed. This model is based on calculations of the photogenerated and diffusion currents in the device. Expressions for the carrier mobilities, absorption coefficient, and normal-incidence reflectivity as a function of temperature are derived from extensions made to Adachi and Caughey-Thomas models. Contributions from the Auger recombination mechanism, which increase with a rise in temperature, are also considered. The responsivity is evaluated for different doping levels, diffusion depths, operating temperatures, and photon energies. Parameters calculated from the model are compared with available experimental data, and good agreement is obtained. These theoretical calculations help us to better understand the electro-optical behavior of In_1–χGa_χSb photodetectors, and can be utilized for performance enhancement through optimization of the device structure.

We describe the application of smectic A (SmA) liquid crystals for beam deflection. SmA materials can be used in digital beam deflectors (DBDs) as fillers for passive birefringent prisms. SmA prisms have high birefringence and can be constructed in a variety of shapes, including single prisms and prismatic blazed gratings of different angles and profiles. We address the challenges of uniform alignment of SmA, such as elimination of focal conic domains. Fast rotation of the incident light polarization in DBDs is achieved by an electrically switched 90-deg twisted nematic (TN) cell.

We experimentally demonstrate a temperature-stable multiwavelength erbium-doped fiber laser source using a high-birefringent photonic crystal fiber (HiBi-PCF) as the birefringent component of the Sagnac loop filter within the laser cavity. Three different high-birefringence (Hi-Bi) fibers are used in the loop filter to compare the temperature stability of the fiber laser systems: polarization-maintaining erbium-doped fiber (PM-EDF), panda Hi-Bi fiber, and HiBi-PCF. Because of the high birefringence and low temperature sensitivity of the HiBi-PCF, fiber length in the loop is greatly reduced and the temperature stability of the system is dramatically enhanced.

A method of gas phase chemical analysis using direct absorption spectroscopy is implemented with long-wavelength vertical-cavity surface-emitting lasers (VCSELs) operating near 1577 nm. The method is based on a linear dependence of widths of collisionally broadened absorption lines on gas pressure. It is shown that the absolute gas concentrations in multicomponent gas mixtures can be extracted from the line widths of all compounds measured simultaneously. The concentrations of both absorbing and nonabsorbing compounds are extracted from the results of simultaneous measurements of peak absorption and line width of the absorbing compound. Long-wavelength VCSELs with a buried tunnel junction (Vertilas, Germany) are used, for the first time, for multispecies and trace gas detection. Continuous single-mode tuning of the VCSELs up to 30 cm^–1 is achieved with temperature and injection current varied in the range 0 to 50 °C and 1.3 to 6.5 mA, respectively. A fractional absorption of ~10^–4 (600 ppm of CO₂ in air) is measured with a single-beam spectroscope. The method described can be used for laser chemical analysis of gas mixtures with relatively high concentrations of target compounds and for open-path trace gas sensing. Compact sensors based on long-wavelength VCSELs can be developed for environmental and industrial gas monitoring.

A low-cost prototype of a laser range finder using a complementary metal-oxide semiconductor (CMOS) image sensor is developed for the automotive field. The system presented here is based on triangulation. The centroid of the infrared laser spot on the CMOS image sensor is converted into pixel coordinates proportional to the distance to be measured. The system is operated in two modes: continuous wave (cw) and pulsed mode. A comparison of these two modes is also conducted and discussed here. Based on the experimental results, the distance can be measured with an accuracy of better than 1.1% within the range of 5 to 45 m.

We describe a new gold-silver complex based on 2,2′-bipyridine, whose formula is {Au₂Ag₂(C₆F₅)₄[(C₅H₄N)-(C₅H₄N)]₂}_n, used to detect volatile organic compounds (VOCs) such as ethanol, methanol, and acetic acid. This organometallic material is presented in the form of bright yellow powder, and suffers a change in its optical properties when it is exposed to VOCs. A new fiber optic sensor is presented based on the properties of a new vapochromic material. The sensor works in a reflection configuration and consists of an optic fiber pigtail (core diameter is 200 µm and cladding is 230 µm) on the cleaved end of which the vapochromic material, previously mixed with a commercially available solvent, Liquicoat®, is deposited by using the dip-coating technique. Using an optical source and a photodetector, it is possible to detect and quantify the change in reflected intensity-modulated signal when the sensor is exposed to VOC inside a sealed chamber. This behavior can be related to the VOC concentration. The study of the sensor's response is made at a specific wavelength for different VOC concentrations. Limits of detection of 2.16, 1.73, and 3.73 mg/L of vapors of ethanol, methanol, and acetic acid vapors, respectively, are attained.

We have designed and fabricated a hollow optical waveguide with omnidirectional reflectors (ODRs) on a silicon substrate. The pattern is defined by photolithography on a (100) silicon wafer. The groove is etched by inductive coupled plasma. Plasma-enhanced chemical vapor deposition technology is used to deposit six-pair Si/SiO₂ (0.111/0.258 µm) multilayer stacks on the sample. Finally, the top of the sample is covered with an identical ODR. Hence, the light is confined in a hollow waveguide.

Based on the guided-mode propagation analysis method and the self-imaging effect, the general imaging properties of the two-dimensional multimode interference coupler (2-D MMI) are generalized and discussed. The general formulas for the positions, intensities, and phases of the self-images, and for image overlap in 2-D MMIs are derived. The numbers, positions, intensities, and phases of the self-images are directly related to the position of the input field and the positional number. The self-imaging properties of 2-D MMIs can be regarded as the interference superposition of two orthogonal one-dimensional self-imaging effects. These results are verified by guided-mode propagation analysis.

We present preliminary experimental results for silicon-on-insulator polarization rotators with asymmetric external waveguiding layers. These devices consist of a waveguide with vertical and sloped sidewalls and are fabricated using a combination of plasma and chemical etching techniques. For a device length of 3256 µm, a TE-to-TM polarization conversion efficiency of 75% was measured.

cw assist light in the gain region or at transparency wavelength of a semiconductor optical amplifier (SOA) is introduced into an SOA-based clock recovery circuit to overcome the pattern effect. A numerical model considering intraband effects in the SOA, such as carrier heating and spectrum hole burning, is constructed to study the pattern effect on clock recovery. The pattern effect reductions for different injection powers and wavelengths of cw assist light and different bias currents of the SOA are simulated to optimize this system. In an experiment, high-quality clock pulses were recovered from a (2³¹–1)-pseudorandom-bit sequence (PRBS) at 20 and 40 Gbit/s by using cw assist light. Simulation and experimental results show that a lower pattern effect can be effectively obtained by using a cw assist light with highest power near the highest-gain wavelength when the SOA works at a high current level. In this respect, cw assist light in the gain region is superior to light at the transparency wavelength. This scheme can be applied to SOA-based all-optical clock recovery and other all-optical signal processing for pattern effect reduction.

The main advantage of using soliton pulses in optical communication systems is that the shape of the pulse remains almost unaltered over a long distance. We propose a simple method to achieve the proper power shape function of a pulse for generation of an optical soliton by using an electro-optic modulator in amplitude modulation mode. In this connection some important new characteristics of the pulse are pointed out.

A novel optical interleaver scheme based on nested optical glass pairs is proposed. The assembly of pairs behaves as a cascaded Mach-Zehnder interferometer. The interleaver, with simple structure, low cost, and compact size, can be easily implemented with inexpensive material and mature preparation technology. Small channel spacing (≤50 GHz), high isolation (<–30 dB), a wide, flat passband and stop band (>2/11 period), and center-frequency tunability can be obtained simultaneously. An optimum design of a 50-GHz tunable interleaver based on this structure is given as an example. Its environmental temperature sensitivity and fabrication tolerance are also analyzed.

This study proposes a spectral polarization coding scheme for the implementation of complementary bipolar optical correlation in a noncoherent optical code-division multiple-access network. The coder-decoders are implemented over differential photodetectors based on fiber Bragg gratings and polarization beamsplitters. Traditionally, complementary unipolar spectral amplitude coding (SAC) schemes are used to transmit the specific codeword on data bit 1 and its complementary codeword on data bit 0. In the proposed scheme, the spectral amplitude is incorporated with polarization coding as the specific signature address code. A Walsh-Hadamard code is employed as the signature address to allocate to each specified wavelength to an individual vertical or horizontal state of polarization. The results indicate that multiple-access interference can theoretically be eliminated by correlation subtraction at the differential photodetectors. Neglecting the effects of shot noise and thermal noise, and considering only phase-induced intensity noise with a degree-of-polarization setting of P=0 for the ideal case, the bit error rate (BER) versus the number of simultaneous active users is improved by 43% in the proposed scheme over the complementary unipolar SAC scheme for a 10^–9 error probability. Setting P=1 for the worst case, the BER performance of the proposed scheme matches that of the complementary unipolar SAC scheme.

Automation of fiber optic alignment is critical to reduce the cost of fiber optic devices packaging and ensure the quality of the products. The conventional fiber optic alignment method based on a hill-climbing algorithm is usually time consuming and it often fails to search the optimal alignment position. The reason is that the hill-climbing algorithm is a 1-D method, while multiple degrees of freedom (DOF) adjustments are needed in fiber optic alignment processes. The hill-climbing algorithm will be subject to noise because of intercoupling among axes. Thus, application of the pattern search algorithm in fiber optic alignment automation is developed in this work. The pattern search algorithm can adjust misalignments on multiple axial directions simultaneously. The intercoupling problem can be solved, and then the potential risk of missing the real peak can be avoided. Comparison of the simulation and experimental results between the pattern search and the hill-climbing algorithm is presented. Simulation results indicate that the pattern search algorithm converges nine times faster than the hill-climbing algorithm; it converges to the maximum coupling efficiency within eight iterations for the five degrees of freedom alignment between the laser diode and the single mode fiber. The experimental results demonstrate that the average time for locating the optimal coupling position in the x-y plane using the pattern search algorithm is reduced compared to the conventional hill-climbing algorithm; and the global convergence of the pattern search algorithm is much better than that of the hill-climbing algorithm.

An advanced continuous wavelet transform algorithm for digital interferogram analysis and processing is proposed. The algorithm is an extension of the traditional wavelet transform; the mother wavelet and normalization parameter are selected based on the characteristics of optical interferograms. To reduce the processing time, a fast Fourier transform scheme is employed to implement the wavelet transform calculation. The algorithm is simple and is a robust tool for interferogram filtering and for whole-field fringe and phase information detection. The concept is verified by computer simulation and actual experimental interferogram analysis.

This paper proposes a novel simple image encryption and decryption technique based on the principle of interference and a binary-phase computer-generated hologram (BPCGH). To obtain a stable interference pattern, a technique involving a photorefractive material is also proposed. The proposed scheme is composed of digital encryption and optoelectronic decryption. For the encryption process, a BPCGH that reconstructs the original image perfectly is designed, using a simulated annealing algorithm, and the resulting hologram is regarded as the image to be encrypted digitally. In addition, a reference image with key information is created using a random two-phase generator. The hologram is then encrypted using the reference image and the interference rule. For the decryption process, the interference intensity is obtained by interfering the reference image and the encrypted image, binarized with software, and then transformed into phase information. Finally, the original image is recovered by an inverse Fourier transformation of the binary-phase information. During this process, since the intensity information generated by the interference of the two images is very sensitive to external vibrations, a stable interference pattern is achieved using a self-pumped phase-conjugate mirror made of the photorefractive material BaTiO₃.

The author introduces new parameters for ice-cloud retrieval: the reduced optical depth and the particle absorption length. The retrieval of these parameters from backscattering solar light measurements depends only weakly on the assumption on the habits of particles made in retrieval procedures. This allows one to avoid major difficulties in modern ice-cloud retrieval algorithms related to a priori assumptions on the shape of crystals in ice clouds.

Pansharpening is a pixel-level fusion technique used to increase the spatial resolution of the multispectral image using spatial information from the high-resolution panchromatic image, while preserving the spectral information in the multispectral image. Various pansharpening algorithms are available in the literature, and some have been incorporated in commercial remote sensing software packages such as ERDAS Imagine® and ENVI®. The demand for high spatial and spectral resolutions imagery in applications like change analysis, environmental monitoring, cartography, and geology is increasing rapidly. Pansharpening is used extensively to generate images with high spatial and spectral resolution. The suitability of these images for various applications depends on the spectral and spatial quality of the pansharpened images. Hence, the evaluation of the spectral and spatial quality of the pansharpened images using objective quality metrics is a necessity. In this work, quantitative metrics for evaluating the quality of pansharpened images are presented. A performance comparison, using the intensity-hue-saturation (IHS)-based sharpening, Brovey sharpening, principal component analysis (PCA)-based sharpening, and a wavelet-based sharpening method, is made to better quantify their accuracies.

We apply the x-ray extended-range technique (XERT) to measure mass attenuation coefficients over one order of magnitude more accurately than previously reported in the literature. We describe the application of the XERT to the investigation of systematic effects due to harmonic energy components in the x-ray beam, scattering and fluorescence from the absorbing sample, the bandwidth of the x-ray beam, and thickness variations across the absorber. The high-accuracy measurements are used for comparison with different calculations of mass attenuation coefficients, and to identify particular regions where these calculations fail.

In the last 20 years, x-ray imaging technology has developed to meet the needs of x-ray photoetching, spatial exploration, high-energy physics, and diagnosis of inertial confinement fusion. Because conventional imaging methods are not suitable in the x-ray range, grazing reflective imaging and coded aperture imaging methods have been adopted. In this paper, we describe the design of a noncoaxial grazing incidence KBA microscope. The microscope consists of two sets of spherical mirrors that scatter in orthogonal planes. An optical ray tracing program is used to analyze and evaluate the theoretical aberrations of the microscope. This allows us to optimize the x-ray imaging system. The analytical results provide a reliable foundation for determining the useful range and the manufacturing and assembly tolerances of the microscope.

Existing methods of 3-D object modeling and recovering 3-D data from uncalibrated 2-D images are subject to errors introduced by assumptions about camera parameters and mismatches in finding point pairs in the images. In this study, we experimentally evaluate the effect of each of these assumptions together with the inaccuracy in the measurements in the images. Sensitivity of reconstruction errors to inaccuracies in the estimation of camera parameters and mismatches due to noise in input data is measured using a linear and two nonlinear autocalibration methods for a projective camera. Our experimental results show that some assumptions such as a vanishing skew can be safely made; however, other parameters such as principal point location are quite sensitive to wrong assumptions.

A novel method of color and texture feature extraction for image retrieval is proposed. First, an input image is divided into 4×4 nonoverlapping blocks. Then, each block is quantized into two colors by color moment preserving and merging similar colors according to their color difference values under a preset threshold value. A few dominant colors are obtained, and a color histogram of the reconstructed image is computed for the color feature. For the texture feature, by preserving some color moments in the 4×4 neighborhood of each pixel, a bitmap is generated, which can be matched with 64 predefined bitmaps. Then a bitmap spectrum is obtained by counting bitmaps frequencies when all pixels of the input image are considered. An efficient method of similarity measurement is also presented. Experimental results show the proposed method performs well in terms of precision and recall.

Face detection from images is a key problem in human computer interaction studies and pattern recognition research. In this work, we propose an efficient genetic algorithm (EGA) that solves the face detection problem in color images. The proposed EGA is based on the Takagi-Sugeno-Kang(TSK)-type fuzzy model employed to perform parameter learning. Compared with traditional genetic algorithms, the EGA uses the sequential-search based-efficient generation (SSEG) method to generate an initial population to determine the most efficient mutation points. Experimental results show that the performance of the EGA is superior to the existing traditional genetic methods.

Optical single backscattering spectroscopy can be used for sizing particles suspended in aqueous solution. In this work, we present results of backscattering spectroscopy applied to the determination of radii of calibrated spherical latex microparticles when a beam of white light is incident on the sample. From Mie calculations and Fourier analysis, we can determine the radius of particles covering the range between 0.5 and 12 µm for monomodal samples, with a mean error of 0.7 µm. To improve the accuracy, a correlation algorithm is applied that reduces the uncertainty in more than an order of magnitude and compares to the traceable error given by the manufacturer. The method can be also applied to bimodal and trimodal samples, allowing the separation of different size components.

A modified class associative fringe-adjusted filter-based technique is proposed for multiple target detection, where the number of processing steps remains fixed irrespective of the number of objects in the class. An enhanced version of generalized fringe-adjusted filters is developed for correlation improvement. Again, a shifted phase encoding technique is employed for generation of a single correlation peak per target object. The effectiveness of the proposed technique is verified by computer simulation for binary as well as gray-level images both with and without noise.

This PDF file contains the errata for “OE Vol. 45 Issue 04 Paper 2197520” for OE Vol. 45 Issue 04