This PDF file contains the editorial “What’s Important?” for OE Vol. 47 Issue 03

For frames involving an abrupt scene change, almost all macroblocks are encoded using intramode in H.264/AVC. Before encoding such frames, one must first determine whether a scene has changed to perform the appropriate rate control. Since the computation load of H.264/AVC is heavy, a more cost-effective algorithm for detecting scene changes is necessary for real-time operations. We propose such an algorithm for high-motion video, and the results show that the proposed algorithm reduces the computational load by 37 to 92% from existing algorithms.

A new unsymmetrical photochromic diarylethene 1a is synthesized, and the photochromic properties of it are also investigated. The compound exhibits good photochromism with UV/visible light irradiation. Compound 1a in polymethyl methacrylate (PMMA) film changes color upon 313-nm light irradiation from colorless to blue, in which the absorption maximum is observed at 587 nm. Photon-mode polarization multiplexing holographic optical recording is performed successfully using this compound as a recording medium. In the diarylethene 1b/PMMA film, polarization multiplexing hologram recording and retrieval, and a combination with the angular multiplexing scheme, are demonstrated systematically. The results indicate that recording capacity can be significantly improved with the combined method of polarization and angular multiplexing holographic recording.

I propose on-time modulation (OTM) to compensate for insufficient time to charge column lines in liquid crystal displays (LCDs). OTM modulates turn-on times of row signals as a function of column signal delay. Most LCD panels for monitors and laptop computer displays adopt a two-line inversion. OTM extends turn-on times of even row signals and reduces pulse widths of the next odd rows. Experimental results showed that turn-on times of even row signals should be unequally extended in accordance with a distance of the row from a column driver. Because OTM successfully solves the charging time problem, it contributes to the success of 120-Hz driving, which has been widely investigated to solve motion blur in LCDs, but has a very severe charging problem.

We discuss a very simple method to encode binary data as circular polarization states with opposite helicity by means of a standard twisted nematic liquid crystal display (TN-LCD). This idea is applied to produce a steganographic imaging system, where binary data are hidden on a background with the same polarization but opposed helicity. A variant is also proposed that maintains some visible information. Experimental results obtained with a commercial TN-LCD are presented.

Among the different instruments that have been selected for the Pasteur payload on ExoMars is the Raman–laser-induced-breakdown-spectroscopy (LIBS) instrument. The novel, and technologically challenging, feature of this instrument is the integration of both Raman spectroscopy and LIBS techniques in the same hardware. An international team under the lead of TNO has been gathered together to produce a combined Raman-spectrometer–LIBS elegant breadboard. The instrument has been designed around an extremely compact spectrometer with a high resolution over a large wavelength range, which is suitable for both Raman spectroscopy and LIBS measurements. Low mass, size, and power consumption are the main drivers of the instrument design concept. A summary of the functional and environmental requirements together with a description of the optical design and its performance are included.

Previously, the author described a closed-form analytical approach to obtaining the complete solution set for four-mirror anastigmats in which all the mirrors were spherical. Two novel types of four-spherical-mirror anastigmats with concave primary were reported. This approach has been modified by setting up baseline systems with good first-order characteristics and adding the minimum number of aspheric lenses necessary to provide anastigmatic correction. In this way, searches for useful four-mirror anastigmats with one, two, or three mirrors kept strictly spherical have been carried out. By using this technique, a system with only one conicoid mirror can be found that has very similar first-order properties and equivalent correction to a system with three conicoids.

In a previous survey, closed-form analytical solutions for four-spherical-mirror anastigmats were developed and used to map the solution space for such systems. In all cases, the systems investigated had objects at infinity, concave primary mirrors, and the primary mirror was always the element with the largest diameter. This survey includes systems with elements larger than the primary mirror. It also includes both new types of concave-primary-mirror systems and all of the convex-primary-mirror systems, which were previously excluded. Numerous systems are presented, including new forms of concentric-mirror systems and systems that have zero Petzval curvature. Also investigated are off-axis or schiefspiegler forms, which include systems excluded from the previous survey due to large central obstructions when considered as on-axis systems. The fact that closed-form solutions are used to map out all solutions over the relevant parameter space means that the systems presented here (together with an earlier survey) represent the full and final range of possibilities for four-spherical-mirror anastigmats for which at least one of the system imaging conjugates is infinite.

When extreme ultraviolet (EUV) mirror systems having several high-order aspheric surfaces are optimized, the configurations sometimes enter into highly unstable regions of the parameter space. Small changes of system parameters lead then to large changes in ray paths and optimization algorithms fail. A technique applicable for any rotationally symmetric optical system that keeps the configuration away from unstable regions during optimization is described. A finite-aberration quantity is computed for several rays, and its average change per surface is determined for all surfaces. For not too large values of these average changes, optimization remains stable. A design for EUV lithography is discussed.

Images describing polarimetric characteristics of objects are more and more used when studying complex scenes. In some cases, only the depolarization phenomenon, mostly due to scattering, proves of interest and estimating the degree of polarization (DOP) is sufficient. For a linearly polarized beam under normal incidence, when the materials in the scene exhibit neither birefringence nor dichroism, this comes down to an intensity measurement in two crossed directions. Nevertheless, the classical optical setup, consisting mainly of a rotating polarizer used as a polarization state analyzer, gives good-quality images, but cannot provide dynamic information. In this paper, we propose to use a ferroelectric liquid-crystal modulator in an imaging polarimeter. We demonstrate the use of this modulator as a polarization state analyzer for frame rates up to about 400 Hz. Provided a fast camera is used, we show that the polarimeter allows us to surpass the classical video frame rate. We propose a setup using a rapid CCD camera (up to 233 Hz). Images in DOP are of very high quality and hold their own against images obtained with a classical polarizer. With a faster camera, we were able to obtain images at up to 400 Hz.

High dynamic range imaging (HDRI) has become a topic of intense research interest in many fields. One kind of HDRI system based on the spatial light modulator (SLM) has a problem with output image instability because of feedback modulation. The HDRI system is introduced, and then a feedback modulation model for the HDRI system is established to discuss the oscillation reason for the output images. The relationship between the input light intensity and the feedback progress is analyzed. A method that adjusts the modulate index of the SLM is proposed to solve the instability problem, and the stability conditions are given to obtain stable images. Lastly, experimental images prove that the feedback model is correct and the output image with high dynamic range is stable.

Optical coherence tomography was used to collect cross-sectional images of glass powder beds consisting of microspheres with diameters ranging from 8 to 175 μm. Images were formed by a collection of individual interferogram envelopes that give the backscattered light amplitude as a function of the optical path in the glass powder bed. The diameter distribution, for microspheres located near the surface of the beds, is obtained by appropriate peak distance measurements on threshold-selected envelopes after having performed the surface profilometry. The measured distributions are in good agreement with those obtained by laser diffraction. When considering the whole powder volume, the evaluation of the mean light penetration depth inside the powder beds proves to be a useful approach to evaluate the mean particle diameter, although no information is obtained on the actual particle size distribution in this case. Two simplified models are introduced to understand the linear relationship observed between the penetration depth and the mean particle size.

In order to have an efficient design methodology and achieve high-performance inertial instruments, it is important to analyze the dynamic characteristics of micromechanical vibratory gyroscopes. In this paper, a novel optical method based on a high-speed CMOS camera and digital image spectrum correlation is developed to measure the motion of the sensitive elements. Unlike digital image correlation (DIC) in the spatial domain, correlation in the spectral domain gives direct access to the whole image under translational motion, which retains all the advantages of DIC and provides an expanded range of measurement. In addition, the proposed method is much faster in computation and capable of calculating dynamic temporal serial images in real time. The proposed method is employed to obtain the displacement of temporal series images and to extract dynamical parameters such as resonant frequency and quality factor at atmospheric pressure. During dynamic testing, the discrete wavelet transform is employed to eliminate the low-frequency components, and the continuous wavelet transform (CWT) for identification of the frequency and damping ratio. Experimental results show that the proposed method is a direct inspection tool and a practical alternative to the conventional electrical measurements of micromechanical vibratory gyroscopes.

A new trinocular stereo matching algorithm is proposed. The collinear trinocular stereo, which is an almost occlusion-free system, is adopted, and the classical binocular stereo algorithm, adaptive support weight, is used for window selection. A novel camera selection technique is presented to utilize the information of different target images more efficiently. Moreover, a trinocular disparity calibration algorithm is introduced, so the initial disparity can be refined and a precise result can be produced. Some image sequences of real scenes are used to evaluate our algorithm. The result shows that the proposed method can extract an accurate disparity map. It is concise and efficient.

A confocal microscopic setup with a pair of birefringent lenses having their crystal axes crossed is used to measure birefringence of thin samples. The method can be used to measure phase down to the order of λ/10. The fast and slow axes of the object also can be identified. The principle of the method along with the experimental setup is described. Some first-order experimental results are also presented.

In the current moiré literature, techniques to determine displacements, strains, and techniques to get geometrical parameters of surfaces using the shadow-projection moiré method are considered two separated branches of moiré. We have formulated a mathematical model that shows a deeper commonality between the two moiré applications: strain fields and surfaces are tensors of the second order. A direct consequence of this property is that a system of orthogonal grids is required in both cases when Cartesian tensors are utilized. The two systems of lines projected on a surface to get its contour are assimilated to parametric lines used in differential geometry to describe a surface. The classical moiré equations of projection and observation from infinity are extended to more general conditions of projection and observation. The use of four projectors (i.e., two groups of two projectors) in a mutually orthogonal system with one camera is shown to provide the necessary means to implement the model for high-accuracy contouring. Geometrical primitives are introduced to provide a simple and direct procedure to reduce all the measured values to a preselected coordinate system. Different views of the same surface are merged to the selected coordinate system directly without the need to introduce markers on the surface or utilize correlation methods to identify identical regions. Examples of the application of the new model of contouring to practical cases are presented in the companion paper "A general model for moiré contouring, part 2: applications."

Applications are presented of the general shadow-projection moiré model described in the companion paper, "A general model for moiré contouring, part 1: theory." Two examples are discussed in detail. One example deals with the deflection of a large-size thin panel subjected to bending. The other example analyzes the accuracy that can be achieved in laser lithography rapid prototyping. The first example illustrates some theoretical aspects of the general contouring model proposed in this research and explains the reasons for differences between theoretical predictions and experimental results. In the second example, the whole process of data gathering and merging using geometric primitives and optimization techniques is demonstrated practically. Finally, a clear relationship between the measured standard deviations and moiré sensitivity values is obtained. The results show that the proposed methodologies lead to a quasi-quadratic correlation.

Combined with the digital image correlation (DIC), the stereo vision calibrated by a circle grid can be used to measure the surface deformation of a deformable body. The grid dot centers are taken as the calibration points. A subpixel localization technique was developed to precisely find the location of the edge points of a dot. A conical section was then fitted to the obtained edge points to locate the dot center so that the intrinsic and extrinsic camera parameters can be accurately extracted after the camera calibration. The baseline measurement error of the stereo vision was evaluated by performing rigid body translation tests. By using the DIC to find the conjugate pairs in stereo images, the calibrated stereo vision is used to measure the strain field of a tension test specimen to evaluate its applicability to the surface deformation measurement of a deformable body.

Three-dimensional data merging is vital for full-field three-dimensional (3D) shape measurement. All 3D range data patches, acquired from either different sensors or the same sensor in different viewing angles, have to be merged into a single piece to facilitate future data analysis. A novel method for 3D data merging using Holoimage is proposed. Similar to the 3D shape measurement system using a phase-shifting method, Holoimage is a phase-shifting–based computer synthesized fringe image. The 3D information is retrieved from Holoimage using a phase-shifting method. If two patches of 3D data with overlapping areas are rendered by OpenGL, the overlapping areas are resolved by the graphics pipeline, that is, only the front geometry can be visualized. Therefore, the merging is performed if the front geometry information can be obtained. Holoimage is to obtain the front geometry by projecting the fringe patterns onto the rendered scene. We also demonstrated that each point of the geometry in the overlapping area can be obtained by averaging the corresponding point of the geometries reconstructed from Holoimage for each patch. Moreover, using Holoimage, the texture can also be obtained. Both simulation and experiments demonstrated the success of the proposed method.

Micro- and nanopolycrystalline VO₂ thin films with hysteretic first-order metal-insulator transition were fabricated by the reactive ion-beam sputtering method. The phase transition temperatures of the micro- and nanopolycrystalline films are at 68 and 45° C, respectively. Using the random-resistor-network model, the characteristics of hysteretic resistance versus temperature are simulated for these films. The modeling results are checked against the experimental measurements. There is satisfactory agreement between the calculated resistance-temperature trajectories and the measured major hysteresis loops for both micro- and nanopolycrystalline films over the whole temperature range from the low-temperature semiconductor behavior to the high-temperature metallic state, which gives strong support to the present approach.

We propose a technique of applying the prism-coupler method for accurate measurement of the effective indices of channel waveguides, which can have step- or graded-index profiles. The technique involves coupling light from a prism into an array of waveguides, varying the angle between the prism axis and the array axis, and curve fitting of the measurement data. We demonstrate the technique with arrays of polymer waveguides and ion-exchanged glass waveguides.

Optical systems involving multimode fibers generally suffer from increased noise. The noise is present whenever nonuniform optical surfaces follow the multimode fiber, unless the fiber and the conditions of the input radiation are perfectly stable. We have demonstrated fiber mode noise in an optical spectrum analyzer measurement, and developed a simple algorithm to predict the amplitude of this noise, based on the transmission properties of the nonuniform optical surfaces. The algorithm can be useful in estimating the overall signal-to-noise ratio in optical systems; it is particularly useful for designing spectroscopic sensors.

We have experimentally investigated a new two-stage C+L-band (1525 to 1605-nm) amplified spontaneous emission (ASE) fiber source using a dual forward pumping configuration. The proposed source offers a high pumping efficiency of 24.6%, output power of about 52 mW, and a wide bandwidth of 80 nm. Without using any external spectral filters, the source has a low spectral ripple between 2.4 and 2.9 dB for different pumping power levels. This designed configuration is also suitable for high-efficiency L-band ASE. The obtained source will be useful in characteristic measurement for wavelength-division multiplexing components and spectrum-sliced multiwavelength fiber sources for local access networks.

Semiconductor optical amplifiers (SOAs) as nonlinear devices always work in the gain saturation region. Therefore, the saturation gain is an important parameter of SOAs. However, the existing theoretical gain formula greatly deviates from the experimental measurements. We find experimentally that the effect of the absorption loss on the SOA gain cannot be neglected, especially when the SOA is biased into the saturation region. In this paper, considering the influence of the absorption loss, we propose a modification to the SOA gain formula in common use. We are able to validate the revised formula against the experimental measurements. Thus the theoretical formula after modification can be accurately applied to evaluate the SOA gain in practice.

The polarization-scrambling technique could be used not only to suppress the polarization-induced detrimental effects in a long-haul lightwave system, but also to monitor various polarization-related parameters. However, this technique could interact with polarization-mode dispersion (PMD) and polarization-dependent loss, and then cause timing jitters, irregular intensity modulations, and PMD-induced repolarization. This problem could be substantially reduced by using the optimized scrambling frequency of about 10 kHz.

Proposes one of the multiuser detection schemes, a new technique that has the potential to reduce interference or suppress multiple-access interference and, therefore, increase the capacity of optical code-division multiple access (CDMA) systems. It is a successive interference cancellation (SIC) scheme known as a low-complexity multiuser detection method for direct sequence CDMA systems. A SIC scheme is analyzed using an optical orthogonal code, with a different power for each user, that takes into account the impact of imperfect interference cancellation.

A 2×2 switch based on an acousto-optic Bragg cell for telecommunications applications was developed. Two Bragg gratings are superimposed in the same crystal by applying two RF signals simultaneously to the cell. This results in the appearance of spurious optical beams. All the unwanted beam characteristics have been evaluated to optimize the performances of this device. The measurements have been made using an optical heterodyne detection method. The cell is made with a planar phased array transducer with a TeO₂ crystal.

In this paper, the investigation of 10 channels at 80-Gb/s wavelength-division-multiplexing (WDM) transmission over 910-km single-mode fiber and dispersion compensating fiber using cascaded in-line semiconductor optical amplifiers at a span of 70 km for soliton return zero differential phase-shift keying (RZ-DPSK) modulation format is achieved. With the narrow channel spacing (i.e., 200 GHz), the results of quality is more than 15 dB the received signals after covering 910-km transmission distance without any power drop. The semiconductor optical amplifier (SOA) structure parameters for in-line amplifier is optimized to obtain low cross talk in multichannel WDM systems at nil power penalty with sufficient gain. For the differential gain 200 atto cm² and length 750 mm of SOA has minimum SOA-induced cross talk is observed. The impact of optical power received and the Q factor at different differential gain, carrier lifetime, and length has been illustrated. It is found that for a transmission distance of 700 km, with decrease the channel spacing, there is an increase in cross talk among channels, hence the signal quality continues to decrease. A clear eye diagram and a good optical spectrum are observed at a transmission distance of 910 km in a soliton RZ-DPSK system.

An optical four-bit parallel-shift register that consists of four serially connected optical flip-flop memories is driven by common clock pulses. Each optical flip-flop consists of two coupled polarization switches that share an all-optical demultiplexer, which makes the optical flip-flops easily connected with each other to form a parallel-shift register. The optical flip-flops are controlled by clock pulses. The parallel-shift register and an optical parallel adder are used to demonstrate an all-optical binary multiplier and its optical control circuit. The concept is demonstrated at an operation speed of 10 MHz for registers and 1 MHz for a multiplier, which is limited by long laser cavities formed by the optical fiber.

An SW-banyan network can play an important role in an optical interconnection network. A smart and compact SW-banyan network with a 2×2 node switch is proposed that uses polarizing beamsplitters (PBSs), phase spatial light modulators (PSLMs), and mirrors. PBS features include an s-component (perpendicular to the incident plane) of the incident light beam that is reflected, and a p-component (parallel to the incident plane) that passes through it. According to switching logic, under the control of external electrical signals, a PSLM controls the routing paths of the signal beams, i.e., the polarization of each optical signal is rotated or not rotated 90 deg by a programmable PSLM. Since the proposed optical setup consists of only optical polarization elements, it is compact in structure and possesses a low energy loss, a high signal-to-noise ratio, and a large number of available optical channels. Finally, the discussions and experimental results show that the SW-banyan network proposed here may be used in optical communication and optical information processing.

A new kind of waveguide and waveguide coupler formed in a nematic liquid crystal (lc) cell is created by means of a weak-intensity laser beam that propagates along the flat boundary between layers of lc and photoconductive polymer. To obtain a waveguide, the connection between the lc and polymer must be driven by the properly polarized voltage. The examined lc cells were of a common kind with indium-tin-oxide (ITO) uniform electrodes on both inner sides of a glass plate. The planar homogeneous alignment of the lc layer was confined by a poly (N-vinyl carbazole) (PVC) layer on one side and a polyimide layer on the opposite side. We applied the PVC doped with a photosensitizer as the photoconductive polymer and a nematic lc mixture of high birefringence. A waveguide was created along a light beam propagation path, and coupling between the waveguides was fabricated in the same way. The energy transfer between the waveguides was proved in properly prepared experiments for laser beam wavelengths equal to 532 nm and 632.8 nm. For both wavelengths, the outcomes of the experiments were of the same quality.

Free-space optics (FSO) has gained considerable importance in this decade of demand for high-bandwidth transmission capabilities. FSO can provide the last mile solution, but the availability and reliability issues concerned with it have received increasing attention and need thorough investigation. In this work, we present our results on fog attenuation measurement and prediction at wavelengths 650, 850, and 950 nm with peak values up to 500 dB/km. For the attenuation measurement, optical wavelengths are transmitted over the same path of fog in free air to a receiver, measuring the power at every wavelength. The measurement of fog attenuation was performed at the France Telecom R&D test facility at La Turbie (in the south of France). We compare our measurement data with the commonly used light attenuation models (Kruse and Kim models) and with a new proposed model allowing the prediction of fog attenuation for the 0.69- to 1.55-μm spectral band. We present some interesting insights and discuss the wavelength dependence. The practical measurements described promise to validate the models and therefore should lead to more accurate availability prediction for FSO links.

A partially coherent vortex beam propagating in a turbulent atmosphere is investigated by using extended Huygens-Fresnel diffraction integral. The influence of the turbulence, the spatial coherence, and the topological charges of the incident beam on the propagation characteristics of the beam is studied in great detail. It is shown that the spreading of the partially coherent vortex beam is less influenced by atmospheric turbulence than that of a partially coherent nonvortex beam, and that a partially coherent vortex beam of lower coherence is less influenced than one of higher coherence.

Lasers play an ever-increasing role in aerospace communication systems by providing the most logical connectivity channels. They drive the advancements in modern optoelectronics; however, successful implementation of this technology hinges on having an equally advanced beam-steering system for tracking the communication counterpart in the presence of complex maneuvers and the resident vibration of the airframe. The work presented in this paper concentrates on the development of agile acousto-optic beam-steering systems for laser communication terminals, which use constant-gain controllers augmented with an adaptive Kalman filter. Experimental results are presented to demonstrate communication performance as a function of the sampling rate in the tracking loop.

A new impulsive noise removal algorithm, the selective adaptive weighted median filter (SAWMF), is introduced. The proposed solution is a class of adaptive weighted median filters with incorporation of a switching mechanism. Using a median-based comparison technique to classify each image pixel as an impulse or a noise-free one, the new algorithm employs a weighted median filter where the weights are adaptively selected from two fixed values to restore the detected noisy pixels and keep the noise-free ones unchanged. The experimental results indicate that the SAWMF provides a significant performance improvement over many of the existing filtering techniques in suppressing impulsive noise with different contamination ratios.

We present a snake-based scheme for efficiently detecting contours of objects with complex boundary concavities. The proposed method is composed of two steps. First, the object's boundary is detected using the proposed snake model. Second, snake points are optimized by inserting new points and deleting unnecessary points to better describe the object's boundary. We use the Frenet formula to calculate the binormal vector at snake points and use the result to control the direction of movement for snake points near boundary concavities. The proposed algorithm can successfully extract objects with boundary concavities. Experimental results have shown that our algorithm produces more accurate segmentation results than the conventional algorithm.

We demonstrate the detection of metallic and nonmetallic foreign bodies in chocolate using pulsed terahertz imaging. Investigating the shape of the temporal waveform allows for the discrimination between wanted ingredients like nuts on one hand and foreign bodies like stone, glass, or plastic particles on the other hand. Yet, the intensity image alone does not provide enough information to evaluate the quality of the chocolate bar. To achieve a low false-alarm rate it is important to measure the height profile of the sample and to include the measured results in the image-processing step. Our results show that terahertz imaging can be used for the detection of contaminations in chocolate bars. Furthermore, other kinds of dry food can be investigated with our technique.

A phase-contrast cone-beam computed tomography (PC CBCT) system is proposed for small-animal imaging that incorporates the in-line holography technique into CBCT system. Theoretical analysis shows that the in-line holographic image can be approximately transformed into line integrals of an object function composed of an attenuation term and a phase term. The Fresnel diffraction theory is applied to generate in-line holographic images along a circular orbit, and the Feldkamp-Davis-Kress algorithm is applied to reconstruct the object function. The proposed system was investigated using a numerical phantom, and the reconstruction was evaluated using the edge-enhancement factor and the relative reconstruction error. The reconstruction results show that all the structures in the numerical phantom are bounded with enhanced edges with negligible artifacts. These enhanced edges make the reconstruction visually sharper and clearer. The results show that while the relative reconstruction errors are very close to that of the conventional CBCT reconstruction, having a small cone angle, weak attenuation, small focal spot size, and high-resolution detector are preferred for a greater edge-enhancement effect.

This paper presents a novel multiresolution approach for texture classification based on the moment features, which are extracted in the x direction and y direction, of a histogram in each image resolution. Then we propose a weighted multiresolution moment feature for supervised texture classification. Moreover, because of their capability of expressing image information using moment methods, these features achieved better performance on rotation invariance and noise robustness than most of popular texture features presented in recent years.

In the traditional vector quantization (VQ) encoding procedure, the quality of all parts of the image is evenly distributed. The code words selected for encoding depend on the complexity of the image and quality requirements. However, VQ cannot be used to enhance the quality of only the regions of interest (ROI). Therefore, an improved weighted cell-split algorithm based on weighted ROI blocks is proposed to train a code book to generate improved code words with emphasis on the ROI blocks. Furthermore, code words can be manipulated to allow the user to define the percentage of ROI emphasis. Experimental results show that the image quality of ROIs is significantly improved by more than 1 dB peak signal-to-noise ratio. Moreover, the improved cell-split algorithm can be easily integrated into the traditional VQ coding procedure since only the contents of the code book are modified. The algorithm can be applied to medical images where the integrity of the ROI blocks is important.

Most existing video compression standards use block-matching motion estimation to exploit temporal correlation between frames. To reduce the costly computation of exhaustive searches on all possible motion displacements, researchers have developed many fast algorithms. Some of these successfully proposed algorithms take advantage of the motion correlations between adjacent macroblocks. On the basis of the idea of second-order motion correlation between macroblocks in particular, we developed a new algorithm that applies a set of adaptive search patterns to benefit the statistical model of motions. In addition, adaptive early termination rules are used to prevent the waste of unnecessary computation. Simulation results show that the proposed algorithm outperforms most other existing algorithms in the areas of speed and visual quality.

We propose a new edge-dependent deinterlacing method using weighted motion estimation. Motion-compensated methods use the motion information and produce improved performance. However, they still tend to produce unsatisfactory picture quality in rapid motion areas and edge regions due to incorrect motion estimation. The proposed method mitigates these problems by limiting motion estimation to an appropriate search range and applying a weighted edge motion estimation with a piecewise linear weight function. Experimental results show that the proposed method provides noticeable improvement in terms of the peak signal-to-noise ratio and produces better picture quality in edge regions.

A multiscale contour matching method using basis functions is presented. In this scheme, curves are parametrized by the curve length s and s′, and contours are matched by finding a matching function s′=f(s). A set of basis functions, which are monotonic and continuous in the interval [0,1], are designed. The sum of these weighted basis functions approximates f(s). The weight of each function can be computed through optimization of the objective function. Multiscale schemes can make matching insensitive to initial value. Experimental validation is carried out with a sequence of human active contours and the result shows this method is effective.

A novel fragile watermarking scheme is proposed. This scheme not only can verify the authenticity and integrity of the video streams with fine granularity scalability, but also can reduce the size of bit streams after embedding fragile watermark information into the base-layer stream and the bit-plane coding symbol in the enhancement-layer stream. For clarifying the effectiveness of the proposed scheme, a series of experimental simulations were conducted. The results show that the scheme can detect tampering modification in the content of video streams and identify the locations at which these modifications have been made. Furthermore, the scheme can further reduce the average length of the compressed bit stream by about 12%.

Automatic processing of digital images of falling raindrops is complicated by a less than ideal grayscale image histogram. These histograms do not display a bimodal shape and lack an easily defined minimum, making it difficult to choose a threshold for creating a binary image. To help identify peaks in these histograms, and simplify threshold selection, a histogram modification technique originally developed by Peleg is used. This method was modified slightly and then applied to raindrop image processing. Its performance is quantified.

Most images f(x,y) are not smoothly differentiable functions of x and y, but display edges, localized singularities, and other significant fine-scale roughness, or texture. Correct characterization and calibration of image roughness is vital in many image processing tasks. The L¹ Lipschitz exponent α, where 0<1α≤1, measures fine-scale image roughness provided the image is relatively noise free. A recently developed mathematical technique for estimating α is described. The method is based on successively blurring the image by convolution with increasingly narrower Gaussians, using commonly available fast Fourier transform algorithms. Instructive examples are used to illustrate the quantitative changes in α that occur when an image is either degraded or restored. Of particular interest are the documented changes in α that accompany APEX blind deconvolution of real images from the Hubble space telescope, from magnetic resonance imaging and positron emission tomography brain scans, and from state-of-the-art nanoscale scanning electron microscopy. Additional applications include monitoring of image sharpness and imaging performance in imaging systems, evaluation of image reconstruction software quality, detection of abnormal fine structure in biomedical images, and monitoring of surface finish in industrial applications.

A new core-point detection method using orientation and edge maps, where a color loop-up table is defined and used to obtain the orientation map, is presented. To achieve high speed detection, all processes are performed with the reduced image. The edge map is obtained by detecting the edges on the orientation map. Then an upper-part maximum edge region is defined as the edge region with maximum area in the edge map. Finally, the core point can be detected simply by finding a point located in the lowest part of the upper-part maximum edge region. Experimental results show that the proposed method can effectively detect the core point for all types of fingerprints including the arch type.

A model for digital image computation of a driving scene during daytime fog has been implemented in order to evaluate targets' visibility. Using a semi-Monte Carlo method to solve the radiative transfer equation inside fog, we establish a physically based rendering with an accurate lighting simulation. The fog is modeled as a layer of water droplets described by a Deirmendjian size distribution, and the scattering properties of each droplet are computed using Mie theory. The boundary conditions are sky luminance and sun illuminance on top of the fog layer, and a bidirectional reflectance distribution function (BRDF) model derived from measurements on road samples. The veiling luminance inside the layer in all directions and for several altitudes is computed and allows us to evaluate the attenuation of every surface existing in the scene. As an example, the visibility of a Lambertian reflective silhouette is given.

As digital multimedia are transmitted more easily and rapidly, pirates can more easily and unlimitedly copy them. Therefore, people are more attentive to intellectual property and copyright protection. Watermarking is a potential technique for copyright protection and authentication of multimedia data on the internet. A watermark, acting like content, is embedded into the original host signal. For digital watermarking of an image, it is often inserted in the spatial or the frequency domain. A watermark can be embedded into the image intensity in the spatial domain, or into the coefficients of the discrete cosine transform in the frequency domain. We propose a novel video-watermarking algorithm based on a block-matching algorithm to achieve copyright protection in the spatial domain. The advantages of our proposed algorithm are robustness against not only signal attacks but also intentional attacks. Moreover, our proposed technique is easy to perform and can provide an adjustable threshold to achieve superior performance in imperceptibility and robustness. The results show that our approach can effectively extract the watermark under various common attacks such as MPEG compression, luminance, noise, filtering, cropping, and blurring, and can thus achieve copyright protection.