This PDF file contains the front matter associated with SPIE Proceedings Volume 7723, including the Title Page, Copyright information, Table of Contents, Introduction and the Conference Committee listing.

Traditionally, optical sensors have been designed to collect the most directly interpretable and intuitive measurements possible. However, recent advances in the fields of image reconstruction, inverse problems, and compressed sensing indicate that substantial performance gains may be possible in many contexts via computational methods. In particular, by designing optical sensors to deliberately collect "incoherent" measurements of a scene, we can use sophisticated computational methods to infer more information about critical scene structure and content. In this paper, we explore the potential of physically realizable systems for acquiring such measurements. Specifically, we describe how given a fixed size focal plane array, compressive measurements using coded apertures combined with sophisticated optimization algorithms can significantly increase image quality and resolution.

Traditional super-resolution methods produce a clean high-resolution image from several observed degraded low-resolution images following an acquisition or degradation model. Such a model describes how each output pixel is related to one or more input pixels and it is called data fidelity term in the regularization framework. Additionally, prior knowledge such as piecewise smoothness can be incorporated to improve the image restoration result. The impact of an observed pixel on the restored pixels is thus local according to the degradation model and the prior knowledge. Therefore, the traditional methods only exploit the spatial redundancy in a local neighborhood and are therefore referred to as local methods. Recently, non-local methods, which make use of similarities between image patches across the whole image, have gained popularity in image restoration in general. In super-resolution literature they are often referred to as exemplarbased methods. In this paper, we exploit the similarity of patches within the same scale (which is related to the class of non-local methods) and across different resolution scales of the same image (which is also related to the fractal-based methods). For patch fusion, we employ a kernel regression algorithm, which yields a blurry and noisy version of the desired high-resolution image. For the final reconstruction step, we develop a novel restoration algorithm. The joint deconvolution/denoising algorithm is based on the split Bregman iterations and, as prior knowledge, the algorithm exploits the sparsity of the image in the shearlet-transformed domain. Initial results indicate an improvement over both classical local and state-of-the art non-local super-resolution methods.

Imaging sensors have physical limitations in spatial resolution, spectral resolution and dynamic range. Super-resolution (SR) image processing technology is to overcome these physical limitations. For decades, numerous researches have been conducted from theoretical points of view, and a variety of high-performance SR algorithms have been proposed. However, there is little work on the implementation of real-world SR imaging system. We have implemented two types of SR imaging systems. First, 9-eye system designed as a prototype is presented, and then 6-eye big system following the prototype is announced and demonstrated. The proposed SR algorithms and a few conventional SR algorithms are applied to both of the SR imaging systems. Problems and further study in SR imaging systems are constructed and discussed through experimental results.

Wavefront coding (WFC) is an imaging technique for enhancing some invariance capabilities of optical instruments (typically invariance against defocus). So far, the procedure has been mostly used in practical environments where the optical aberrations of the optical system correspond to a rotationally symmetrical one, i.e., on-axis imaging. These problems have been extensively tackled in recent years, leading to successful designs like the cubic and petal-shaped phase plates. An interesting aspect of the implementation of the phase plate is the use of a liquid crystal spatial light modulator (SLM) placed at the pupil of the instrument, since it allows enhanced versatility. Under these circumstances, the characteristics of the pupil phase plate, in order to provide invariance, refer only to spherical and defocus aberrations. However, when the optical system is not rotationally symmetrical, like for field imaging, the theoretical framework of the problem is quite different, as one has to deal with more general aberrations. Our aim is to analyze this field imaging invariance problem when using WFC techniques and to try to extend the well known on-axis techniques to this new application.

We propose an adaptive optics system using a Liquid crystal on Silicon Spatial Light Modulator (LCOS-SLM) for wavefront control. The phase diversity technique is used as a wavefront sensor, which estimates a wavefront aberration using processing images acquired by mission sensor instead of using additional wavefront sensor hardware. Because of simplicity in a hardware architecture, the phase diversity technique is suitable especially for a light weight remote sensing satellite. In the conventional phase diversity method, prior information, which is defined as a phase diversity, is applied to the optical system by defocusing. Then wavefront aberrations are estimated using the phase diversity and acquired images. For generating prior information, we uses the LCOS-SLM which generate arbitrary wavefront shape. In this cases, the selection of the phase diversity affect the estimation accuracy of the wavefront aberration. This paper describes the selection strategy of phase diversities, and then validates it by laboratory test.

James Webb Space Telescope (JWST) has a segmented Primary Mirror (PM). PM is made of 18 beryllium hexagonal shaped segments. Flat-to-flat dimension of a segment is 1.315 meters. The PM is an ellipsoid of~ 6.5 meters in diameter with a conic constant of -0.99666 and a radius of curvature ~16 meters. After the PM, telescope are assembled and instruments are installed the observatory will go through environmental testing. The environmental test consist of acoustic and vibration test. The objective is to measure the change in the surface astigmatism of the Primary mirror segments at center of curvature before and after vibration and acoustic test. At the final stage of assembly the inner segments of the PM have no external fiducials. The challenge is to separate the alignment astigmatism from surface astigmatism without any external fiducials. This paper describes an alignment method that uses the print-through in the mirror segments as fiducials to separate the two astigmatisms.

In the paper we present the design of a wide viewing angle display system capable of displaying digital holograms captured in a rotary CCD configuration. We have discussed the two possible configurations of multi LC SLMs system: with a normal LC SLM illumination and with tilted LC SLMs and parallel illumination. The second system was selected and the tilted plane algorithm, necessary for recalculation of displayed holograms was tested. Finally we have presented and discussed different means of visual perception of holographic images: with an asymmetric diffuser and with an eyepiece.

We present a new slot-in type of optical correlator that is more compact than the previous types. The correlator can fit inside the cabinet of commercial personal computers and is fully controllable with windows-based software. The correlator is a Joint Transform type (JTC) and its optical system fits inside a metal box measuring 140 mm (W) x 220 mm (L) x 40 mm (H). The optical source is a 650-nm-band laser diode of the kind used in DVD systems. A spatial light modulator and a CMOS camera are installed in the metal box with the passive optical components required for the JTC. The collimated light from the laser diode is illuminated on the spatial light modulator displaying reference and data to be examined. The light reflected from the modulator is Fourier-transformed by a lens on the plane of the CMOS camera. The computer reads the power spectrum recorded by the camera and modulates the spatial light modulator. This process is repeated. We found that these JTC processes could be performed with the prototype developed in this study.

Recent advances in computer-generated images (CGI) have been used in commercial and industrial photography providing a broad scope in product advertising. Mixing real world images with those rendered from virtual space software shows a more or less visible mismatching between corresponding image quality performance. Rendered images are produced by software which quality performance is only limited by the resolution output. Real world images are taken with cameras with some amount of image degradation factors as lens residual aberrations, diffraction, sensor low pass anti aliasing filters, color pattern demosaicing, etc. The effect of all those image quality degradation factors can be characterized by the system Point Spread Function (PSF). Because the image is the convolution of the object by the system PSF, its characterization shows the amount of image degradation added to any taken picture. This work explores the use of image processing to degrade the rendered images following the parameters indicated by the real system PSF, attempting to match both virtual and real world image qualities. The system MTF is determined by the slanted edge method both in laboratory conditions and in the real picture environment in order to compare the influence of the working conditions on the device performance; an approximation to the system PSF is derived from the two measurements. The rendered images are filtered through a Gaussian filter obtained from the taking system PSF. Results with and without filtering are shown and compared measuring the contrast achieved in different final image regions.

In this paper, we examine the rate-distortion performance in terms of perceptual quality of JPEG XR (ISO/IEC 29199-2 | ITU-T Rec. T.832)1 and earlier standardized image compression algorithms such as JPEG (ISO/IEC 10918-1 | ITU-T Rec. T.81)2 and JPEG 2000 (ISO/IEC 15444-1 | ITU-T Rec. T.800)3. Unfortunately, objective visual quality metrics (like MSE, PSNR, VQM, SSIM, etc.) do not always correlate well with the actual perceived image quality. In some specific cases, it is even possible that certain visible coding artifacts remain undetectable by these objective visual quality tests. As such, we conducted a series of subjective visual quality assessment tests to measure the visual performance of JPEG XR, JPEG 2000 and JPEG. This paper describes the design of the subjective visual quality assessment experiments, addressing the encountered difficulties and potential pitfalls. Our results indicate that for high bit-rates (i.e. more than 1 bpp) all three codecs more or less have an equal overall performance. However, as expected, at lower bit-rates JPEG performs significantly weaker for every tested image than JPEG 2000 and JPEG XR. On the other hand, both JPEG 2000 and JPEG XR appear to be very competitive at these low bit-rate ranges. Only for specific image content types (e.g. smooth gradient surfaces), JPEG XR appears to have some difficulties. Nevertheless, discarding the fact that JPEG 2000 offers more functionality features than JPEG XR, the latter performed very good for most images and almost in par with JPEG 2000. As a conclusion, the results of the subjective visual quality assessment tests show that JPEG XR successfully passed our verification experiments for low dynamic range imagery.

At present time, image fusion is widely recognized as an important aspect of information processing. It consists of combining information originated from several sources in order to improve the decision making process. In particular, multi-focus image fusion combines images that depict the same scene but they are not in-focus everywhere. The task seeks to reconstruct an image as sharp as possible by preserving in-focus areas while discarding blurred areas. The quality of fused images is of fundamental importance. Many objective quality metrics for image fusion have been proposed. However, the evaluation of fused images is still a difficult task, especially because there is no reference image to compare with. Blind image quality assessment refers to the problem of evaluating the visual quality of an image without any reference. In this paper, we describe a blind image fusion quality assessment procedure based on the use of mutual information (MI). This procedure is concise and explicit and will be useful in scenarios where the absence of a reference image can hamper the assessment of the results. Furthermore, several image fusion algorithms have been rated and they have shown that our metric is compliant with subjective evaluations. Consequently, it can be used to compare different image fusion methods or to optimize the parameter settings for a given fusion algorithm.

This paper proposes a novel image enhancement technique based on Gamma Map Processing (GMP). In this approach, a base gamma map is directly generated according to the intensity image. After that, a sequence of gamma map processing is performed to generate a channel-wise gamma map. Mapping through the estimated gamma, image details, colorfulness, and sharpness of the original image are automatically improved. Besides, the dynamic range of the images can be virtually expanded.

Digital long-term preservation has become an important topic not only in the preservation domain, but also due to facilitation by several national and international projects like US National Digital Information Infrastructure and Preservation Program [1], the German NESTOR project [2] and the EU FP7 SHAMAN Integrated Project [3]. The reason for this is that a large part of nowadays produced documents and other goods are digital in nature and even some - called "born-digital" - have no analog master. Thus a great part of our cultural and scientific heritage for the coming generations is digital and needs to be preserved as reliable as it is the case for physical objects even surviving hundreds of years. However, the continuously succession of new hardware and software generations coming in very short intervals compared to the mentioned time spans render digital objects from just some generations ago inaccessible. Thus they need to be migrated on new hardware and into newer formats. At the same time integrity and authenticity of the preserved information is of great importance and needs to be ensured. However this becomes a challenging task considering the long time spans and the necessary migrations which alter the digital object. Therefore in a previous work [4] we introduced a syntactic and semantic verification approach in combination with the Clark-Wilson security model [5]. In this paper we present a framework to ensure the security aspects of integrity and authenticity of digital objects especially images from the time of their submission to a digital long-term preservation system (ingest) up to its latter access and even past this. The framework especially describes how to detect if the digital object has retained both of its security aspects while at the same allowing changes made to it by migration.

With the tremendous growth and usage of digital images nowadays, the integrity and authenticity of digital content is becoming increasingly important, and a growing concern to many government and commercial sectors. Image Forensics, based on a passive statistical analysis of the image data only, is an alternative approach to the active embedding of data associated with Digital Watermarking. Benford's Law was first introduced to analyse the probability distribution of the 1st digit (1-9) numbers of natural data, and has since been applied to Accounting Forensics for detecting fraudulent income tax returns [9]. More recently, Benford's Law has been further applied to image processing and image forensics. For example, Fu et al. [5] proposed a Generalised Benford's Law technique for estimating the Quality Factor (QF) of JPEG compressed images. In our previous work, we proposed a framework incorporating the Generalised Benford's Law to accurately detect unknown JPEG compression rates of watermarked images in semi-fragile watermarking schemes. JPEG2000 (a relatively new image compression standard) offers higher compression rates and better image quality as compared to JPEG compression. In this paper, we propose the novel use of Benford's Law for estimating JPEG2000 compression for image forensics applications. By analysing the DWT coefficients and JPEG2000 compression on 1338 test images, the initial results indicate that the 1st digit probability of DWT coefficients follow the Benford's Law. The unknown JPEG2000 compression rates of the image can also be derived, and proved with the help of a divergence factor, which shows the deviation between the probabilities and Benford's Law. Based on 1338 test images, the mean divergence for DWT coefficients is approximately 0.0016, which is lower than DCT coefficients at 0.0034. However, the mean divergence for JPEG2000 images compression rate at 0.1 is 0.0108, which is much higher than uncompressed DWT coefficients. This result clearly indicates a presence of compression in the image. Moreover, we compare the results of 1st digit probability and divergence among JPEG2000 compression rates at 0.1, 0.3, 0.5 and 0.9. The initial results show that the expected difference among them could be used for further analysis to estimate the unknown JPEG2000 compression rates.

In this paper, the effect of binary labelling bins for lattice quantization index modulation techniques is studied. The problem can be solved in one dimension using Gray codes but it is not straightforward for higher dimensions due to more directionality. We show the impact of different labellings on the overall performance of two-dimensional lattice quantization index modulation watermarking systems. Heuristically, we present solutions for these systems, where our analysis includes (1) robustness tests against JPEG and JPEG 2000 compression and (2) transmission over an AWGN channel.

The Discrete Pascal Transform (DPT) has been proved remarkably useful for edge detection, filter design, discrete-time signal interpolation and data hiding. In the present work a new blind fragile data hiding technique for secretly embedding messages into color images, is proposed. The embedding procedure is based on dividing each color image component into even-sized blocks. Information embedding is determined by monitoring the lower-right corner of the DPT coefficient matrix. This particular coefficient suffers the highest change for small pixel modifications. The embedding affects the coefficient's sign. In case that the sign is not the desired one, i.e. negative for a message bit value of '0' and positive for a message bit value of '1', it is changed by repeatedly adding to the block or subtracting from the block the identity matrix. This process is based on the DPT properties and on the sensitivity of the lower-right coefficient in even the smallest pixel changes. The embedding algorithm takes care of the underflows or overflows that may occur during the consecutive additions or subtractions. The method is evaluated in terms of capacity and image distortion. Experiments are conducted using different images and block sizes namely 2x2 / 4x4 / 8x8 / 16x16, and the overall performance of the scheme is quantified. Block size greatly affects capacity and stego-image quality. Comparisons with existing methods prove the superiority of the proposed method.

In this paper we propose a new imperceptible yellow printer dot watermarking scheme for documents printed on a colour printer. The scheme takes advantage of the imperfections of the human visual system to hide thousands of yellow dots over the entire page. It takes inspiration from the methods used by laser printer manufacturers for printer identification. The novelty of our approach is in providing an automatic embedding and detection method that can survive the distortions of printing and scanning. In order to achieve this a new moving window detection method is proposed. An error correction code is employed to handle the errors that could be present following detection. The scheme is evaluated through embedding and detection experiments on different types of documents; including text, architectural drawings and a cartoon. Our scheme offers an embedding capacity of 26,190 bits per page. Experiments were conducted using error correction codes with rates of 1/2, 1/3 and 1/5, given payloads of 13,095, 8,730, and 5,238 bits per A4 page respectively. We are able to successfully recover the watermark in all documents at a rate of 1/2 and 1/5, and in all document except one at 1/3. Further experiments were conducted with a smaller dot size to evaluate the impact it has on our results. With the smaller dot size we were still able to recover the watermarks from all documents when using an error correction code with rate 1/5. The capacity offered by this approach far exceeds the capacity offered by existing binary watermarking schemes, which are robust to printing and scanning. The substantially larger capacity opens up a wider range of possible applications as well as the possibility of using more robust cryptographic techniques for authentication.

Content-based audio authentication watermarking techniques extract perceptual relevant audio features, which are robustly embedded into the audio file to protect. Manipulations of the audio file are detected on the basis of changes between the original embedded feature information and the anew extracted features during verification. The main challenges of content-based watermarking are on the one hand the identification of a suitable audio feature to distinguish between content preserving and malicious manipulations. On the other hand the development of a watermark, which is robust against content preserving modifications and able to carry the whole authentication information. The payload requirements are significantly higher compared to transaction watermarking or copyright protection. Finally, the watermark embedding should not influence the feature extraction to avoid false alarms. Current systems still lack a sufficient alignment of watermarking algorithm and feature extraction. In previous work we developed a content-based audio authentication watermarking approach. The feature is based on changes in DCT domain over time. A patchwork algorithm based watermark was used to embed multiple one bit watermarks. The embedding process uses the feature domain without inflicting distortions to the feature. The watermark payload is limited by the feature extraction, more precisely the critical bands. The payload is inverse proportional to segment duration of the audio file segmentation. Transparency behavior was analyzed in dependence of segment size and thus the watermark payload. At a segment duration of about 20 ms the transparency shows an optimum (measured in units of Objective Difference Grade). Transparency and/or robustness are fast decreased for working points beyond this area. Therefore, these working points are unsuitable to gain further payload, needed for the embedding of the whole authentication information. In this paper we present a hierarchical extension of the watermark method to overcome the limitations given by the feature extraction. The approach is a recursive application of the patchwork algorithm onto its own patches, with a modified patch selection to ensure a better signal to noise ratio for the watermark embedding. The robustness evaluation was done by compression (mp3, ogg, aac), normalization, and several attacks of the stirmark benchmark for audio suite. Compared on the base of same payload and transparency the hierarchical approach shows improved robustness.

This paper presents a method able to optimize watermarking detection in the MPEG-4 AVC compressed domain. The optimization was achieved by introducing a statistical counter -attack based on the MAP criterion applied on the noise matrices corresponding to each attack. As no statistical models are nowadays available for the attack effects in the MPEG-4 AVC domain, they had to be first estimated. In this respect, 95% confidence limits for noise matrices, computed with relative errors lower than 15% have been obtained for geometric attacks (StirMark, small rotations), and linear or non-linear filtering (Gaussian filtering, sharpening). The viability of these statistical results was demonstrated by the watermarking experiments: it was obtained that the counter-attacks based on the attack model approaches its theoretical upper limit.

In this paper we present a novel 3D scanner to capture the texture characteristics of worn carpets into images of the depth. We first compare our proposed scanner to a Metris scanner previously attempted for this application. Then, we scan the surface of samples from the standard EN1471 using our proposed scanner. We found that our proposed scanner offers additional benefits because it has been specifically designed for carpets, performing faster, cheaper, better and also a lot more suitable for darker carpets. The results of this approach give optimistic expectations in the automation of the label assessment dealing with multiple types of carpets.

An unsupervised novelty detection method for automatic flaw segmentation in textile materials that has no need of any defect-free references or a training stage is presented in this paper. The algorithm is based on the structural feature extraction of the weave repeat from the Fourier transform of the sample image. These features are used to define a set of multiresolution bandpass filters adapted to the fabric structure that operate in the Fourier domain. Inverse Fourier transformation, binarization and merging of the information obtained at different scales lead to the output image that contains flaws segmented from the fabric background. The whole process is fully automatic and can be implemented either optical or electronically. Fabrics having a superstructure of colored squares, bands, etc. superimposed to the basic web structure can be advantageously analyzed using NIR illumination and a camera sensitive to this region of the spectrum. The contrast reduction of the superstructure signal in the NIR image facilitates fabric structure inspection and defect segmentation. Underdetection and misdetection errors can be noticeably reduced in comparison with the inspection performed under visible illumination. Experimental results are presented and discussed for a variety of fabrics and defects.

Metrology is the key to an economically feasible production of fiber-reinforced composites in the field of automated tape laying, applying a novel laser light-section sensor system (LLSS) to measure process quality and feed back the results to close control loops of the production system. The developed method derives 3D measurements from height profiles through an in-process surface scan by the integrated LLSS. Gaps, overlaps, misalignment and defects of the composite tapes are detected during their lay-up and consolidation by comparing the measurement results with a CAD/CAM model of the lay-up. The height profiles are processed with a novel algorithm based on a non-linear least-square fitting to a set of sigmoid functions to ensure sub-pixel accuracy.

Production metrology faces challenges connected to the production industry where consumers of products expect a standard of high quality at inexpensive costs. One approach for the next generation of production metrology devices aims at ensuring the quality of the process technologies in every single process step, therefore measuring in-process. One example of today's production metrology devices is the measurement of shafts in the production. Shafts are vital for every mechanical device that translates rotational energies and the tolerances based on diameter or roundness are in the range of microns. Those shaft measurement devices are either based on tactile measurements or on visible light which cannot be utilized as an in-process device. A novel idea is to use X-rays instead of tactile or visible light methods to be able to acquire robust measurement data despite of distorting debris like water, oil or dust. One focus is set on algorithms that allow robust measurements of diameter and roundness despite of distorting debris like water, oil or dust. The measurement uncertainty of the new method has been investigated and results will be introduced.

We report a passively Q-switched two-component visible laser light source based on frequency conversion. The device consists of a monolithic single transverse mode ridge-waveguide infrared laser diode and a waveguide-type periodically poled magnesium oxide doped lithium niobate crystal for second harmonic light generation. An integrated 45-degree folding mirror and a coupling lens are formed by etching on opposite sides of the monolithic gallium arsenide -based laser diode for coupling the infrared emission into the waveguide-type nonlinear crystal for efficient single pass frequency conversion. Passively Q-switched operation is realized by an integrated electro-absorber section coupled with the in-plane multi-quantum well gain structure. Stable high-repetition rate self-pulsating operation was achieved by reverse-biasing the electro-absorber section and reduced speckle visibility of the second harmonic light was observed when compared to continuous-wave operation of the same laser.

The combination of laser light sources and MEMS technology enables a range of display systems such as ultra small projectors for mobile devices, head-up displays for vehicles, wearable near-eye displays and projection systems for 3D imaging. Images are created by scanning red, green and blue lasers horizontally and vertically with a single two-dimensional MEMS. Due to the excellent beam quality of laser beams, the optical designs are efficient and compact. In addition, the laser illumination enables saturated display colors that are desirable for augmented reality applications where a virtual image is used. With this technology, the smallest projector engine for high volume manufacturing to date has been developed. This projector module has a height of 7 mm and a volume of 5 cc. The resolution of this projector is WVGA. No additional projection optics is required, resulting in an infinite focus depth. Unlike with micro-display projection displays, an increase in resolution will not lead to an increase in size or a decrease in efficiency. Therefore future projectors can be developed that combine a higher resolution in an even smaller and thinner form factor with increased efficiencies that will lead to lower power consumption.

In this paper, we propose a novel design to construct a near-to-eye display with an appearance resembling that of a regular eye wear. Our design combines a scanning display engine with a diffractive exit pupil expander. Both of these components have been used separately earlier, but we propose to combine them in a single device. This allows the construction of a smaller and lighter display system, as well as a more power efficient design as compared to traditional micro display based systems. In our design the light source can be moved away from the display to decrease the weight and size. An exit-pupil expander based on diffractive optics allows a size and weight efficient way to build a near-to-eye display with a large exit pupil. A large exit pupil is desired in near-to-eye displays to accommodate the eye movements and to improve the comfort and ease of the use. The diffractive exit-pupil expander also allows a switchable see-through feature; enabling the viewer the see the surroundings together with the displayed information. In the paper the operation and the design of the proposed near-to-eye display are described. We also present modeling results that support the validity of the design, and finally some preliminary measurement results are given.

We present a LED light source solution based on a variable chip and package platform for color sequential embedded pico projection. These RGB LEDs are optimized to fulfill the requirements on luminous efficacy (lm/W), size and cost for a variety of pico projector engine designs. Efficacies of 7-10lm at 1W can be achieved for DMD™ and LCoS based projector systems with engine sizes <10cc.

We present compact illumination engines for DMD projection systems making use of light emitting diodes (LEDs) as light sources. The impact of uniformization optics and color-combining dichroic filters is investigated with respect to the color uniformity on the screen. PhlatLight LEDs are considered as light sources because of their superior luminance levels. Also PhotonVacuum optics are used to collimate and transform the emitted LED light distribution. The optical engines are simulated with advanced non-sequential ray tracing software. They are evaluated on the basis of étendue efficiency, compactness and color uniformity of the projected images. Color plots are used as tools to investigate the simulated color gradients in the image. To validate our simulation models, we have built a compact prototype LED projector. Its color-related specifications are compared with the simulated values.

We have developed a Near-to-Eye Display (NED) technology based on diffractive optics. Thin and highly transparent plastic light guides enable a light-weight and ergonomic see-through NED design. We have previously reported of a compact NED with an integrated gaze tracker. Eye gaze tracker can detect the user's focus point in the displayed image. We have now made advances to further increase the level of integration as well as to enable the optical see-through. Originally, three separate light guides were used: two for the display (red, green/blue) and one for infrared light of the gaze tracker. To reduce weight and the system complexity, a shared light guide is now used for transmitting red (~630 nm, display) and infrared (~850 nm, gaze tracker) wavelengths. In addition, shared output gratings are used for outcoupling the light. Light guide plates have been characterized by measuring their modulation transfer functions. Measurements show that the deterioration of the NED's resolution, caused by the light guides, is reduced with improved manufacturing techniques. Also, it has been verified that the additional gratings for infrared (light in-coupling and expansion areas) do not have a notable effect on the display resolution.

The main issue in this paper is to deploy a compressing algorithm for heterogeneous content (text, graphics, image and video) with low-complex decoding. Such an algorithm will be involved in the remote display core problem for mobile thin clients: it allows the graphical content, computed on a remote server, to be displayer on the user's thin terminal, even when the network constraints (bandwidth, errors) are very strict. The paper is structured into three parts. First, a client-server architecture is presented. On the server side, the graphical content is parsed, converted and binary encoded into the MPEG 4 (BiFS, LASeR) format. This content is further streamed to the terminal, where it is played into a simple MPEG player. Secondly, this architecture is considered as a test bed for MPEG 4 performance assessment for various types of content (image, graphics, text). The quantitative results were focussed on bandwidth requirements and quality of experience. Finally, the conclusions are structured as a reference benchmarking of the MPEG (BiFS, LASeR) and outside (VNC) mobile remote display potential solutions.

In this paper we present a wavelet-based coding approach for semi-regular meshes, which spatially adapts the employed wavelet basis in the wavelet transformation of the mesh. The spatially-adaptive nature of the transform requires additional information to be stored in the bit-stream in order to allow the reconstruction of the transformed mesh at the decoder side. In order to limit this overhead, the mesh is first segmented into regions of approximately equal size. For each spatial region, a predictor is selected in a rate-distortion optimal manner by using a Lagrangian rate-distortion optimization technique. When compared against the classical wavelet transform employing the butterfly subdivision filter, experiments reveal that the proposed spatially-adaptive wavelet transform significantly decreases the energy of the wavelet coefficients for all subbands. Preliminary results show also that employing the proposed transform for the lowest-resolution subband systematically yields improved compression performance at low-to-medium bit-rates. For the Venus and Rabbit test models the compression improvements add up to 1.47 dB and 0.95 dB, respectively.

Molecular imaging based on Fluorescence Resonance Energy Transfer (FRET) is widely used in cellular physiology both for protein-protein interaction analysis and detecting conformational changes of single proteins, e.g. during activation of signaling cascades. However, getting reliable results from FRET measurements is still hampered by methodological problems such as spectral bleed through, chromatic aberration, focal plane shifts and false positive FRET. Particularly false positive FRET signals caused by random interaction of the fluorescent dyes can easily lead to misinterpretation of the data. This work introduces a Nipkow Disc based FRET microscopy system, that is easy to operate without expert knowledge of FRET. The system automatically accounts for all relevant sources of errors and provides various result presentations of two, three and four dimensional FRET data. Two examples are given to demonstrate the scope of application. An interaction analysis of the two subunits of the hypoxia-inducible transcription factor 1 demonstrates the use of the system as a tool for protein-protein interaction analysis. As an example for time lapse observations, the conformational change of the fluorophore labeled heat shock protein 33 in the presence of oxidant stress is shown.

This paper shows how local directional entropy can be used as a tool to build up a robust local image descriptor for image feature extraction. Among other possible choices, the Rényi entropy has been selected as the main technique for this application. Local directional entropy which is related with the anisotropy images has been considered here as the basis for the design of a new Rényi entropy-based local image descriptor (RELID). The properties of this new descriptor are described and evaluated. The experimental results confirm that the new descriptor is endowed by most of the invariant properties desired for object recognition applications.

Automatic liver segmentation is a crucial step for diagnosis and surgery planning. To extract the liver, its tumors and vessels, we developed an active contour model with an embedded classifier, based on a Gaussian mixture model fitted to the intensity distribution of the medical image. The difference between the maximum membership of the intensities belonging to the classes of the object and those of the background is included as an extra speed propagation term in the active contour model. An additional speed controlling term slows down the evolution of the active contour when it approaches an edge, making it quickly convergent to the ideal object. The developed model has been applied to liver segmentation. Some comparisons are made between the Geodesic Active Contour, C-V (active contour without edges) and our model. As the experiments show, our model is accurate, flexible and suited to extract objects surrounded by a complicated background.

Increasing demand from consumers to integrate camera modules into electronic devices, such as cell phones, has driven the cost of camera modules down very rapidly. Now that most cell phones include at least one camera, consumers are starting to ask for better image quality - without compromising on the cost. Wafer level optics has emerged over the past few years as an innovative technology enabling simultaneous manufacturing of thousands of lenses, at the wafer level. Using reflow-compatible materials to manufacture these lenses permits a reduction in the cost and size of camera module, thus answering the market demand for lowering the cost. But what about image quality? The author will present image quality analysis that was conducted for both VGA and megapixel camera resolutions. Comparison between conventional camera modules and wafer level camera modules shows wafer level technology brings equivalent, if not better, image quality performance compared to conventional camera modules.

We present the design of a 24 mm long variable focus lens for 1/4" sensor. The chosen CMOS color sensor has VGA (640×480) resolution and 5.6 μm pixel size. The lens utilizes one Varioptic Arctic 320 liquid lens that has a voltage-controllable focal length due to the electrowetting effect. There are no mechanical moving parts. The principle of operation of the liquid lens is explained briefly. We discuss designing optical systems with this type of lens. This includes a modeling approach that allows entering a voltage value to modify the configuration of the liquid lens. The presented design consists only of spherical glass surfaces. The choice to use spherical surfaces was made in order to decrease the costs of manufacturing and provide more predictable performance by the better established method. Fabrication tolerances are compensated by the adjustability of the liquid lens, further increasing the feasibility of manufacturing. The lens is manufactured and assembled into a demonstrator camera. It has an f-number of 2.5 and 40 degree full field of view. The effective focal length varies around 6 millimeters as the liquid lens is adjusted. In simulations we have achieved a focus distance controllable between 20 millimeters and infinity. The design differs from previous approaches by having the aperture stop in the middle of the system instead of in front.

Computational imaging technology can modify the acquisition process to capture extra information at the sensor that can be used for various photographic applications, including imaging with extended depth of field, refocusing photographs after the image is taken or depth extraction for 3D applications. In this paper, we propose a generalized phase coded imaging which involves encoding of the captured light and post-capture decoding for improved features and performance. Phase coded optics utilizes optics to purposely encode specific object information in a more efficient way, which is the most flexible and cost effective solution for correcting optical aberrations or any other optical functions. Practically any shape can be generated on any lens surface for shaping the point spread function of the lens module to achieve desired image results. Phase coded optics is a more general scheme than previous proposed for finding the optimal solutions in digital imaging systems and has proven to be an enabling technology to the imaging problem. Some of the possible applications based on this technique are also investigated in this paper.

The current CMOS image sensors market trend leads to achieve good image resolution at small package size and price, thus CMOS image sensors roadmap is driven by pixel size reduction while maintaining good electro-optical performances. As both diffraction and electrical effects become of greater importance, it is mandatory to have a simulation tool able to early help process and design development of next generation pixels. We have previously introduced and developed FDTD-based optical simulations methodologies to describe diffraction phenomena. We recently achieved to couple them to an electrical simulation tool to take into account carrier diffusion and precise front-end process simulation. We propose in this paper to show the advances of this methodology. After having detailed the complete methodology, we present how we reconstruct the spectral quantum efficiency of a pixel. This methodology requires heavy-to-compute realistic 3D modeling for each wavelength: the material optical properties are described over the full spectral bandwidth by a multi-coefficient model, while the electrical properties are set by the given process and design. We optically simulate the propagation of a dozen of wavelengths at normal incidence and collect the distribution of the optical generation then we insert it in the electrical simulation tool and collect the final output quantum efficiency. Besides, we compare the off-axis performance evaluations of a pixel by simulating its relative illumination in a given wavelength. In this methodology several plane waves are propagated with different angles of incidence along a specific direction.

In recent years CCD manufacturers have been supplying their devices with multi-purpose abilities to manipulate the CCD's readout pattern, where one of these versatile options is a flexible pixel binning option. The pixel binning is a process of combining multiple pixel charges in horizontal, vertical or in both directions simultaneously, into a single charge. The binning process positively influences to the signal-to-noise ratio, sensitivity and frame rate at the cost of decreasing spatial resolution, which, in its turn, negatively influences to the spatial frequency response of the imaging system (i.e. to the output image quality). The modulation transfer function (MTF) is an essential measure for characterizing the spatial-frequency response of the array imaging system. In this work we have performed a theoretical and experimental investigation of the MTF of CCD array in the context of the pixel binning option. We have derived a generalized equation of the geometrical MTF for the v x h binning mode, where v and h denote the numbers of binned pixels in vertical and horizontal directions, respectively. The MTF measurements were performed using a method, based on the generation of laser speckle and utilizing the high resolution (1360×1024) monochrome CCD array. The MTF of normal mode, 2×1-horizontal, 1×2 - vertical, and 2x2 quadratic binning modes were measured by employing single-slit aperture method. CCD binning is widely used in spectroscopy, astronomy, in many image processing applications, such as autofocus, object tracking, etc. The results of this work can be useful for designing optical systems, involving CCD pixel binning option.

A simple low resolution volumetric display is presented, based on holographic volume-segments. The display system comprises a proprietary holographic screen, laser projector, associated optics plus a control unit. The holographic screen resembles a sheet of frosted glass about A4 in size (20x30cm). The holographic screen is rear-illuminated by the laser projector, which is in turn driven by the controller, to produce simple 3D images that appear outside the plane of the screen. A series of spatially multiplexed and interleaved interference patterns are pre-encoded across the surface of the holographic screen. Each illumination pattern is capable of reconstructing a single holographic volume-segment. Up to nine holograms are multiplexed on the holographic screen in a variety of configurations including a series of numeric and segmented digits. The demonstrator has good results under laboratory conditions with moving colour 3D images in front of or behind the holographic screen.

The creation of a simple or an interactive multimedia (MM) system can improve the presentation of a project and, in the case of the conservation of energy, it can highlight the numerous possibilities of the RES and help non-expert users be acquainted with them. The use of text, graphics, images, animations, video, and sound provides a more impressive and more complete way of presentation. This paper focuses on the development and implementation of an MM application for the saving of energy in a working place through the use of photovoltaic elements, a wind generator and geothermal heat exchanger. In particular, the mentioned RES, the MM applications together with all the special features that safeguard their proper function are illustrated and included in the present application. The study reveals: - The importance of RES. - The appropriateness of the MM presentation for informing potential users. - The appropriateness of the MM application in physics classes related to RES resources and RES exploitation.

In recent years it has been more common to see 3D visualization of objects applied in many different areas. In neuroscience research, 3D visualization of neurons acquired at different depth views (i.e. image stacks) by means of confocal microscopy are of increase use. However in the best case, these visualizations only help to have a qualitative description of the neuron shape. Since it is well know that neuronal function is intimately related to its morphology. Having a precise characterization of neuronal structures such as axons and dendrites is critical to perform a quantitative analysis and thus it allows to design neuronal functional models based on neuron morphology. Currently there exists different commercial software to reconstruct neuronal arbors, however these processes are labor intensive since in most of the cases they are manually made. In this paper we propose a new software capable to reconstruct 3D neurons from confocal microscopy views in a more efficient way, with minimal user intervention. The propose algorithm is based on finding the tubular structures present in the stack of images using a modify version of the minimal graph cut algorithm. The model is generated from the segmented stack with a modified version of the Marching Cubes algorithm to generate de 3D isosurface. Herein we describe the principles of our 3D segmentation technique and the preliminary results.

3D reconstruction of blood vessels is a powerful visualization tool for physicians, since it allows them to refer to qualitative representation of their subject of study. In this paper we propose a 3D reconstruction method of retinal vessels from fundus images. The reconstruction method propose herein uses images of the same retinal structure in epipolar geometry. Images are preprocessed by RISA system for segmenting blood vessels and obtaining feature points for correspondences. The correspondence points process is solved using correlation. The LMedS analysis and Graph Transformation Matching algorithm are used for outliers suppression. Camera projection matrices are computed with the normalized eight point algorithm. Finally, we retrieve 3D position of the retinal tree points by linear triangulation. In order to increase the power of visualization, 3D tree skeletons are represented by surfaces via generalized cylinders whose radius correspond to morphological measurements obtained by RISA. In this paper the complete calibration process including the fundus camera and the optical properties of the eye, the so called camera-eye system is proposed. On one hand, the internal parameters of the fundus camera are obtained by classical algorithms using a reference pattern. On the other hand, we minimize the undesirable efects of the aberrations induced by the eyeball optical system assuming that contact enlarging lens corrects astigmatism, spherical and coma aberrations are reduced changing the aperture size and eye refractive errors are suppressed adjusting camera focus during image acquisition. Evaluation of two self-calibration proposals and results of 3D blood vessel surface reconstruction are presented.

In the paper we show that the biologically motivated conception of time-pulse encoding usage gives a set of advantages (single methodological basis, universality, tuning simplicity, learning and programming et al) at creation and design of sensor systems with parallel input-output and processing for 2D structures hybrid and next generations neuro-fuzzy neurocomputers. We show design principles of programmable relational optoelectronic time-pulse encoded processors on the base of continuous logic, order logic and temporal waves processes. We consider a structure that execute analog signal extraction, analog and time-pulse coded variables sorting. We offer optoelectronic realization of such base relational order logic element, that consists of time-pulse coded photoconverters (pulse-width and pulse-phase modulators) with direct and complementary outputs, sorting network on logical elements and programmable commutation blocks. We make technical parameters estimations of devices and processors on such base elements by simulation and experimental research: optical input signals power 0.2 - 20 uW, processing time 1 - 10 us, supply voltage 1 - 3 V, consumption power 10 - 100 uW, extended functional possibilities, learning possibilities. We discuss some aspects of possible rules and principles of learning and programmable tuning on required function, relational operation and realization of hardware blocks for modifications of such processors. We show that it is possible to create sorting machines, neural networks and hybrid data-processing systems with untraditional numerical systems and pictures operands on the basis of such quasiuniversal hardware simple blocks with flexible programmable tuning.

In this paper we define operators based on local vector space representation for detecting changes in images when the illumination of the scenes varies. The difference image contains information from objects not present in original images. Most change image detection algorithms assume that the illumination of a scene will remain invariable. But when the illumination conditions of a scene cannot be controlled, image processing algorithms must be adapted. Here we propose methods based on a local vector model when the illumination of a scene may vary locally and when no knowledge about the illumination parameters is available. We evaluate three operators for image difference independently of local changes of intensity. In addition, all difference local operators are defined in terms of correlations which can be useful for optical implementations using conventional Vander Lugt or joint transform correlators.

A research is carried out on the characteristics of CMOS (Complementary Metal-Oxide Semiconductor) image sensors. A CMOS image sensor is used to probe the fluorescence intensity of atoms or absorbed photons in order to measure the shape and atomicity density of Rb (Rubidium) cold-atom-cloud. A series of RGB data of images is obtained and the spectrum response curve of CMOS image sensor is deduced. After filtering out the noise of the pixel signals of CMOS image sensor, the number of photons received by every pixel of the CMOS image sensor is obtained. Compared with CCD camera, the CMOS image sensor has some advantages in measuring the properties of cold-atom-cloud,such as quick response, large sensory area, low cost, and so on.

A deterministic phase-encoded encryption system, which adopts a lenticular lens array (LLA) sheet as a phase modulator (key), based on arbitrary two-step phase-shift interferometry (PSI), with an unknown phase step, is presented. The principle of encryption and decryption which is using a LLA in arbitrary unknown two-step PSI is given. With the aid of key holograms (right key), it can be theoretically shown that only the reconstructed object wavefront term will be left in the image plane, and all the accompany undesired terms be eliminated. Thus the hidden information of object wavefront in this encryption system can be numerically and successfully decrypted using arbitrary unknown two-step PSI with right key. For comparisons, computer simulations are carried out to verify the principle of encryption and decryption without key, with wrong key and with right key, respectively.

One of widely used methods to extract boundaries of objects in the image is the contour method based on the energy models. Two well known energy models are the edge based and the region based model. Although each of the two models works well with its own advantage, it has difficulty in the following situation: When the initial point the contour evolving starts from is not located properly in the inside region of an object or some objects are partially overlapped so that the intensity difference between boundary pixels on the overlapped area and their neighbors becomes relatively small, the edge based model approach fails to produce good results. On the other hand, the region based model approach fails to produce good results when more than two objects with different intensity averages exist. To overcome such difficulty, we suggest the hybrid energy model approach constructed partially from each of the two approaches. In this approach, some initial point the contour evolving starts from is randomly selected from the image. From the selected initial point the contour starts evolving until it meets the boundary of either some object or background. Once the boundary of one object or background is found, its region is removed from the image. On the rest of the image, the same procedure is repeated until the boundaries of all objects and background are found. The suggested approach is illustrated using SEM images of semiconductor wafers.

We propose here a new and novel technique using the dual modulation modes of the spatial light modulator (SLM) in a single-beam set-up, thus enabling a more compact and more shock-proof holographic image storage and retrieval system when compared to a double-beam interference set-up system.

This paper proposes a digital image restoration algorithm for phase-coded imaging systems. In order to extend the depth-of- field (Dof), an imaging system equipped with a properly designed phase-coded lens can achieve an approximately constant point spread function (PSF) for a wide range of depths. In general, a phase-coded imaging system produces blurred intermediate images and requires subsequent restoration processing to generate clear images. For low-computational consumer applications, the kernel size of the restoration filter is a major concern. To fit for practical applications, a pyramid-based restoration algorithm is proposed in which we decompose the intermediate image into the form of Laplacian pyramid and perform restoration over each level individually. This approach provides the flexibility in filter design to maintain manufacturing specification. On the other hand, image noise may seriously degrade the performance of the restored images. To deal with this problem, we propose a Pyramid-Based Adaptive Restoration (PBAR) method, which restores the intermediate image with an adaptive noise suppression module to improve the performance of the phase-coded imaging system for Dof extension.

A new phase mask typology for wavefront-coding is proposed, the meshed phase mask (MPM). It is intended to be a flexible form in order to be easily adaptable. The use of an evaluating criterion to measure the performance of the MPM is used to optimize its shape. The MPM is uniquely defined by the fixed phase in a number of control points equally spaced in the pupil area. These control points define a regular mesh, and the continuous MPM phase surface is obtained from cubic spline interpolation. A global search algorithm is used to optimize the values at the control points, thus optimizing the MPM. The preliminary results show an improvement over the conventional cubic phase mask, especially in reducing the undesired artefacts in the final restored images.

Development, testing, verification and comparison of various image processing techniques require suitable database of test images. In this paper the DEIMOS, an open-source database, is introduced. This database is aiming various application fields of image processing such as enhancement, compression and reconstruction. At first requirements on different image classes are defined in respect to the specific area of application. The paper also describes basic parameters of the database. There are selected application examples to illustrate extensive database content. The DEIMOS database is created gradually step-by-step based upon the contributions of team members.

Fluorescence lifetime detection is widely used in molecular biology to monitor many cell parameters (such as pH, ion concentrations, etc.) and for an early diagnosis of many pathologies. In a typical fluorescence lifetime experiment a pulsed laser is used to excite the fluorescent dyes and the emitted light is revealed by means of high sensitivity detectors, typically: intensified CCD, PMTs or Single-Photon Avalanche Diodes (SPADs).In this contribute we present a SPAD detector module fabricated in a 0.35μm High Voltage CMOS technology to be used within a lab-on-chip system consisting of a micro-reactor array for bioaffinity assays based on fluorescence markers. The detector module, having a total area of 600 x 900 μm2, can be arranged to build a small pixel array to be directly coupled to the micro-reactors. No emission filters are needed, since the ultra-short laser pulse is cut off in the time domain. The module consists of a 10x10-SPAD array, where each SPAD cell is equipped with dedicated active quenching and recharging circuit. Each cell has a pitch of 26μm with a fill factor of 48%. The SPADs have been binned in order to realize a large photosensitive area detector exhibiting a reasonably low dark count rate (DCR) and reduced dead time, as required in a fast measurement system. A memory has also been implemented in order to enable only low DCR SPADs, so that a total DCR of about 100kHz can be achieved for the whole photosensitive area. The digital output generated by the SPAD array is sent to a time-discriminator stage which allows a time-gated detection of the incident light. Two time-windows have been implemented in this architecture. Their time width is controlled by an on-chip digital PLL locked to the external laser clock whereas the width of the time-windows can be set within the range 500ps-10ns with a resolution of 500ps. Photons detected within each time window are then counted by two 10-bits digital counters. Time-interleaved operation has been implemented to read out the pixel data in parallel with the photon detection phase.

Particle tracking velocimetry (PTV) is a non-invasive, full field optical measuring technique that has become one of the dominant tools for obtaining velocity information in fluid motion. In PTV experiments, the fluid of interest is seeded with fluorescent tracer particles, where measurement of individual particle displacements, recorded by means of digital camera at two instances of time, is further used to ascertain overall flow motion. Upper limit of a flow speed a PTV system can measure is bound by the frame rate of a camera used, and the system's accuracy is limited by the accuracy of the particle centroid estimation. In order to increase the upper limit, we investigated the use of CCD binning option, which doubles camera frame rate, preserves effective field of view, suppresses photon and readout noise of CCD at the expense of loss in spatial resolution. This study provides quantitative assessment of tradeoff between aforementioned advantages of binning over the loss in spatial resolution, which can increase uncertainty in particle centroid estimation. We carried our experiments using scientific grade PixeFly camera and analyzed 1μm and 1.9μm size red fluorescence polystyrene microspheres, placed on a quartz glass plate, by the Hirox variable zoom lens (1-10x) conjugated with a OL- 700II objective. For each binning mode (horizontal, vertical and composite), we investigated and reported estimation errors of various cross-correlation and center of mass based centroid localization methods, using more than 100.000 particle image pairs. We found that, performing vertical binning in the context of laminar flows doubled measurable flow rate, while caused only a negligible estimation error in the order of hundredth of a pixel.

We present a theoretical multi-frequency multi-sampling frequency-domain fluorescence lifetime imaging (FLI) technique, which determines fluorescence lifetime by measuring the phase delay and decrease of the modulation of the emission relative to the excitation. Such a system could be realized with high-speed line-scan cameras using more than 100000 frames per second. It is useful for the measurement of lifetimes in the microsecond range and can be, e.g., used to measure oxygen concentrations with Ruthenium complexes. Typically 100 samples are used, resulting in a temporal resolution of microsecond fluorescence lifetime measurement. By including frequency components with frequencies much higher than the Nyquist criterion, the measurement of fluorescence lifetimes much shorter than the sampling interval is possible. In order to optimize the SNR of the predict lifetimes, we investigate the photon economy of our technique. Various ranges of the exposure time relative to the range of modulation period and compositions of multiple frequencies have been studied. The presented approach is validated by numerical simulations by Monte Carlo method.

Lesion segmentation is crucial in liver pathology diagnosis and surgery planning. Its goal is to identify lesion's shape, location and connectivity to the vessel system. Nowadays, the clinical practice is to use volumetric contrast enhanced CT images, acquired before and after contrast agent injection. However, currently, liver CAD systems work on a single volumetric image, i.e. the volume exhibiting the best contrast enhancement. Therefore, the motivation of our work is to explore the gray-level enhancement in the different abdominal tissues and organs present in all acquired images. The described method at first aligns all images and progresses with the segmentation - a combination of an initial clustering approach and the Expectation-Maximization algorithm to optimally model the joint histogram by a sum of multivariate Gaussian distributions. It is performed hierarchically: firstly, it is invoked on the whole abdominal volume, secondly on the detected liver region, and finally over the lesions. Experiments show that if the contrast information is sufficient, the results are accurate in comparison to the ground truth: reference segmentation performed by a radiologist using a commercial tool. Moreover, we show that our method provides beneficial information to radiologists about the lesion nature and its behavior throughout the different phases.

We present experimental investigation of a new reconstruction method for off-axis digital holographic microscopy (DHM). This method effectively suppresses the object auto-correlation, commonly called the zero-order term, from holographic measurements, thereby suppressing the artifacts generated by the intensities of the two beams employed for interference from complex wavefield reconstruction. The algorithm is based on non-linear filtering, and can be applied to standard DHM setups, with realistic recording conditions. We study the applicability of the technique under different experimental configurations, such as topographic images of microscopic specimens or speckle holograms.