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Showing papers on "Subpixel rendering published in 2007"


Journal ArticleDOI
TL;DR: The proposed technique would also allow precise coregistration of images for the measurement of surface displacements due to ice-flow or geomorphic processes, or for any other change detection applications.
Abstract: We describe a procedure to accurately measure ground deformations from optical satellite images. Precise orthorectification is obtained owing to an optimized model of the imaging system, where look directions are linearly corrected to compensate for attitude drifts, and sensor orientation uncertainties are accounted for. We introduce a new computation of the inverse projection matrices for which a rigorous resampling is proposed. The irregular resampling problem is explicitly addressed to avoid introducing aliasing in the ortho-rectified images. Image registration and correlation is achieved with a new iterative unbiased processor that estimates the phase plane in the Fourier domain for subpixel shift detection. Without using supplementary data, raw images are wrapped onto the digital elevation model and coregistered with a 1/50 pixel accuracy. The procedure applies to images from any pushbroom imaging system. We analyze its performance using Satellite pour l'Observation de la Terre (SPOT) images in the case of a null test (no coseismic deformation) and in the case of large coseismic deformations due to the Mw 7.1 Hector Mine, California, earthquake of 1999. The proposed technique would also allow precise coregistration of images for the measurement of surface displacements due to ice-flow or geomorphic processes, or for any other change detection applications. A complete software package, the Coregistration of Optically Sensed Images and Correlation, is available for download from the Caltech Tectonics Observatory website

777 citations


Journal ArticleDOI
TL;DR: A computationally simple super-resolution algorithm using a type of adaptive Wiener filter that produces an improved resolution image from a sequence of low-resolution video frames with overlapping field of view and lends itself to parallel implementation.
Abstract: A computationally simple super-resolution algorithm using a type of adaptive Wiener filter is proposed. The algorithm produces an improved resolution image from a sequence of low-resolution (LR) video frames with overlapping field of view. The algorithm uses subpixel registration to position each LR pixel value on a common spatial grid that is referenced to the average position of the input frames. The positions of the LR pixels are not quantized to a finite grid as with some previous techniques. The output high-resolution (HR) pixels are obtained using a weighted sum of LR pixels in a local moving window. Using a statistical model, the weights for each HR pixel are designed to minimize the mean squared error and they depend on the relative positions of the surrounding LR pixels. Thus, these weights adapt spatially and temporally to changing distributions of LR pixels due to varying motion. Both a global and spatially varying statistical model are considered here. Since the weights adapt with distribution of LR pixels, it is quite robust and will not become unstable when an unfavorable distribution of LR pixels is observed. For translational motion, the algorithm has a low computational complexity and may be readily suitable for real-time and/or near real-time processing applications. With other motion models, the computational complexity goes up significantly. However, regardless of the motion model, the algorithm lends itself to parallel implementation. The efficacy of the proposed algorithm is demonstrated here in a number of experimental results using simulated and real video sequences. A computational analysis is also presented.

270 citations


Journal ArticleDOI
TL;DR: In this paper, an image analysis technique for subpixel estimation of particle positions is proposed, and an algorithm is proposed to minimize the total error and pixel locking in a dusty plasma experiment.
Abstract: The moment method is an image analysis technique for subpixel estimation of particle positions. The total error in the calculated particle position includes effects of pixel locking and random noise in each pixel. Pixel locking, also known as peak locking, is an artifact where calculated particle positions are concentrated at certain locations relative to pixel edges. We report simulations to gain an understanding of the sources of error and their dependence on parameters the experimenter can control. We suggest an algorithm, and we find optimal parameters an experimenter can use to minimize total error and pixel locking. For a dusty plasma experiment, we find that a subpixel accuracy of 0.017 pixel or better can be attained. These results are also useful for improving particle position measurement and particle tracking velocimetry using video microscopy in fields including colloids, biology, and fluid mechanics.

170 citations


Patent
14 May 2007
TL;DR: In this paper, a display system consisting of a subpixelated display panel and a backlight array of individually controllable multicolor light emitters is described. But the backlight control is not considered in this paper.
Abstract: In one embodiment, a display system includes a subpixelated display panel and a backlight array of individually controllable multicolor light emitters. When the display panel (160) comprises a multi-primary subpixel arrangement having a white (clear) subpixel, the backlight control (130) techniques allows the white subpixel to function as a saturated primary display color. In another embodiment, the display system may calculate a set of virtual primaries for a given image and process the image using a novel field sequential control employing the virtual primaries. In another embodiment, a display system comprises a segmented backlight comprising: a plurality of N + M light guides, said light guides forming a N x M intersections; a plurality of N + M individually addressable light emitter units, each of said N + M light emitter unit being associated with and optically connected to one of said N + M light guide respectively.

119 citations


Journal ArticleDOI
TL;DR: In this article, two new source extraction methods, based on Bayesian model selection and using the Bayesian information criterion, are presented. And they are incorporated in SUSSEXtractor, the source extraction pipeline for the forthcoming Akari Far-Infrared Surveyor all-sky survey.
Abstract: We present two new source extraction methods, based on Bayesian model selection and using the Bayesian information criterion. The first is a source detection filter, which is able to simultaneously detect point sources and estimate the image background. The second is an advanced photometry technique that measures the flux, position (to subpixel accuracy), local background, and point-spread function. We apply the source detection filter to simulated Herschel SPIRE data and demonstrate the filter's ability to both detect point sources and simultaneously estimate the image background. We use the photometry method to analyze a simple simulated image containing a source of unknown flux, position, and point-spread function; we not only accurately measure these parameters but also determine their uncertainties (using Markov chain Monte Carlo sampling). The method also characterizes the nature of the source (distinguishing between a point source and an extended source). We demonstrate the effect of including additional prior knowledge. Prior knowledge of the point-spread function increases the precision of the flux measurement, while prior knowledge of the background has only a small impact. In the presence of higher noise levels, we show that prior positional knowledge (such as might arise from a strong detection in another wave band) allows us to accurately measure the source flux even when the source is too faint to be detected directly. These methods are incorporated in SUSSEXtractor, the source extraction pipeline for the forthcoming Akari Far-Infrared Surveyor all-sky survey. They are also implemented in a stand-alone, beta-version tool that is freely available.

119 citations


Journal ArticleDOI
TL;DR: A novel method to enhance license plate numbers of moving vehicles in real traffic videos is proposed by fusing the information derived from multiple, subpixel shifted, and noisy low-resolution observations to obtain a high-resolution image of the number plate.
Abstract: In this paper, a novel method to enhance license plate numbers of moving vehicles in real traffic videos is proposed. A high-resolution image of the number plate is obtained by fusing the information derived from multiple, subpixel shifted, and noisy low-resolution observations. The image to be superresolved is modeled as a Markov random field and is estimated from the observations by a graduated nonconvexity optimization procedure. A discontinuity adaptive regularizer is used to preserve the edges in the reconstructed number plate for improved readability. Experimental results are given on several traffic sequences to demonstrate the robustness of the proposed method to potential errors in motion and blur estimates. The method is computationally efficient as all operations can be implemented locally in the image domain

115 citations


Journal ArticleDOI
TL;DR: Results demonstrate improved performance over the well-known AMSD and ACE subpixel algorithms in experiments that include multiple targets, images, and area types - especially when dealing with weak targets in complex backgrounds.
Abstract: Subpixel detection is a challenging problem in hyperspectral imagery analysis. Since the target size is smaller than the size of a pixel, detection algorithms must rely solely on spectral information. A number of different algorithms have been developed over the years to accomplish this task, but most detectors have taken either a purely statistical or a physics-based approach to the problem. We present two new hybrid detectors that take advantage of these approaches by modeling the background using both physics and statistics. Results demonstrate improved performance over the well-known AMSD and ACE subpixel algorithms in experiments that include multiple targets, images, and area types - especially when dealing with weak targets in complex backgrounds.

100 citations


Journal ArticleDOI
TL;DR: In this paper, it is shown that the interpolation has a smoothing effect which depends of the applied shift. And a strategy to attenuate the interpolations artifacts is proposed to increase the quality of the similarity estimation.
Abstract: Subpixel accuracy image registration is needed for applications such as digital elevation model extraction, change detection, pan-sharpening, and data fusion. In order to achieve this accuracy, the deformation between the two images to be registered is usually modeled by a displacement vector field which can be estimated by measuring rigid local shifts for each pixel in the image. In order to measure subpixel shifts, one uses image resampling. Sampling theory says that, if a continuous signal has been sampled according to the Nyquist criterion, a perfect continuous reconstruction can be obtained from the sampled version. Therefore, a shifted version of a sampled signal can be obtained by interpolation and resampling with a shifted origin. Since only a sampled version of the shifted signal is needed, the reconstruction needs only to be performed for the new positions of the samples, so the whole procedure comes to computing the value of the signal for the new sample positions. In the case of image registration, the similarity between the reference image and the shifted versions of the image to be registered is measured, assuming that the maximum of similarity determines the most likely shift. The image interpolation step is thus performed a high number of times during the similarity optimization procedure. In order to reduce the computation cost, approximate interpolations are performed. Approximate interpolators will introduce errors in the resampled image which may induce errors in the similarity measure and therefore produce errors in the estimated shifts. In this paper, it is shown that the interpolation has a smoothing effect which depends of the applied shift. This means that, in the case of noisy images, the interpolation has a denoising effect, and therefore, it increases the quality of the similarity estimation. Since this blurring is not the same for every shift, the similarity may be low for a null shift (no blurring) and higher for shifts close to half a pixel (strong blurring). This paper presents an analysis of the behavior of the different interpolators and their effects on the similarity measures. This analysis will be done for the two similarity measures: the correlation coefficient and the mutual information. Finally, a strategy to attenuate the interpolation artifacts is proposed

97 citations


Patent
09 Mar 2007
TL;DR: In this paper, a white subpixel adjustment operation is proposed to adjust the brightness of the white subpixels in the areas of the displayed image that contain high spatial frequency features such as lines and text.
Abstract: A display device comprises a display panel comprising high brightness subpixel repeating groups—for example, RGBW display panels. Displays comprise subpixel repeating groups that include first and second primary color stripes and third and fourth primary color subpixels that are disposed on a checkerboard pattern. A subpixel rendering operation includes, or is followed by, a white subpixel adjustment operation that adjusts the brightness of the white subpixels in the areas of the displayed image that contain high spatial frequency features such as lines and text, in order to improve image quality such as image contrast.

82 citations


Journal ArticleDOI
TL;DR: A method for overcoming the pixel-limited resolution of digital imagers is presented, which combines optical point-spread function engineering with subpixel image shifting and places an optimized pseudorandom phase mask in the aperture stop of a conventional imager.
Abstract: We present a method for overcoming the pixel-limited resolution of digital imagers. Our method combines optical point-spread function engineering with subpixel image shifting. We place an optimized pseudorandom phase mask in the aperture stop of a conventional imager and demonstrate the improved performance that can be achieved by combining multiple subpixel shifted images. Simulation results show that the pseudorandom phase-enhanced lens (PRPEL) imager achieves as much as 50% resolution improvement over a conventional multiframe imager. The PRPEL imager also enhances reconstruction root-mean-squared error by as much as 20%. We present experimental results that validate the predicted PRPEL imager performance.

70 citations


Journal ArticleDOI
TL;DR: An algorithm for applying the PWS SR filters to video that is computationally efficient and suitable for parallel implementation is presented and a number of experimental results are presented to demonstrate the efficacy of the proposed algorithm in comparison to several previously published methods.
Abstract: We propose a computationally efficient super-resolution (SR) algorithm to produce high-resolution video from low-resolution (LR) video using partition-based weighted sum (PWS) filters. First, subpixel motion parameters are estimated from the LR video frames. These are used to position the observed LR pixels into a high-resolution (HR) grid. Finally, PWS filters are employed to simultaneously perform nonuniform interpolation (to fully populate the HR grid) and perform deconvolution of the system point spread function. The PWS filters operate with a moving window. At each window location, the output is formed using a weighted sum of the present pixels within the window. The weights are selected from a filter bank based on the configuration of missing pixels in the window and the intensity structure of the present pixels. We present an algorithm for applying the PWS SR filters to video that is computationally efficient and suitable for parallel implementation. A number of experimental results are presented to demonstrate the efficacy of the proposed algorithm in comparison to several previously published methods. A detailed computational analysis of the partition-based SR filters is also presented

Journal ArticleDOI
TL;DR: It is shown how the even powers of the normalized Fourier transform of an image are invariant to centrally symmetric blur, such as motion or out-of-focus blur, and proposed blur-invariant phase correlation is proposed.
Abstract: In this paper, we propose an image registration method, which is invariant to centrally symmetric blur The method utilizes the phase of the images and has its roots on phase correlation (PC) registration We show how the even powers of the normalized Fourier transform of an image are invariant to centrally symmetric blur, such as motion or out-of-focus blur We then use these results to propose blur-invariant phase correlation The method has been compared to PC registration with excellent results With a subpixel extension of PC registration, the method achieves subpixel accuracy for even heavily blurred images

Journal ArticleDOI
TL;DR: It is found that linear interpolation methods lead to average radiometric errors below 2% for the correction of spatial PSF nonuniformity in the subpixel domain, whereas the replacement of missing pixels leads to average errors in the range of 10%-20%
Abstract: Efficient and accurate imaging spectroscopy data processing asks for perfectly consistent (i.e., ideally uniform) data in both the spectral and spatial dimensions. However, real pushbroom-type imaging spectrometers are affected by various point spread function (PSF) nonuniformity artifacts. First, individual pixels or lines may be missing in the raw data due to bad pixels originating from the detector, readout errors, or even electronic failures. Second, so-called smile and keystone optical aberrations are inherent to imaging spectrometers. Appropriate resampling strategies are required for the preprocessing of such data if emphasis is put on spatial PSF uniformity. So far, nearest neighbor interpolations have been often recommended and used for resampling. This paper shall analyze the radiometric effects if linear interpolation is used to optimize the spatial PSF uniformity. For modeling interpolation effects, an extensive library of measured surface reflectance spectra as well as real imaging spectroscopy data over various land cover types are used. The real measurements are systematically replaced by interpolated values, and the deviation between original and resampled spectra is taken as a quality measure. The effects of nearest neighbor resampling and linear interpolation methods are compared. It is found that linear interpolation methods lead to average radiometric errors below 2% for the correction of spatial PSF nonuniformity in the subpixel domain, whereas the replacement of missing pixels leads to average errors in the range of 10%-20%

Journal ArticleDOI
TL;DR: This work reports an application of the correct approximation of inverse permittivity tensor epsilon(-1) at the material interface for conductive and dispersive media for Mie scattering from a small sphere.
Abstract: Staircasing of media properties is one of the intrinsic problems of the finite-difference time-domain method, which reduces its accuracy There are different approaches for solving this problem, and the most successful of them are based on correct approximation of inverse permittivity tensor epsilon(-1) at the material interface We report an application of this tensor method for conductive and dispersive media For validation, comparisons with analytical solutions and various other subpixel smoothing methods are performed for the Mie scattering from a small sphere

Journal ArticleDOI
TL;DR: In this paper, a near-infrared spot projection system has been developed, and the effect of subpixel non-uniformity was studied, showing that for detectors with near 100% internal quantum efficiency, 1% photometry can be achieved with a point-spread function (PSF) size of about half a pixel.
Abstract: Wide‐field survey instruments are used to efficiently observe extended regions of the sky. To achieve a large field of view and to provide a high signal‐to‐noise ratio for faint sources, many modern instruments are undersampled. However, in undersampled detectors, sensitivity variations across individual pixels can severely impact science programs that require high photometric precision. To address this, a near‐infrared spot projection system has been developed. With this system, 1.7 μm cutoff detectors were characterized, and the effect of subpixel nonuniformity was studied. The measurements demonstrate that for detectors with near 100% internal quantum efficiency, 1% photometry can be achieved with a point‐spread function (PSF) size of about half a pixel. For detectors with large subpixel nonuniformity, photometric errors become negligible only if the PSF size is more than about two pixels.

Journal ArticleDOI
TL;DR: Analysis of landscape pattern metrics derived from remotely sensed images covering different study areas, sensor spatial resolutions, and classification approaches concludes that scaling functions may be useful and reasonably accurate for estimating pattern metrics at the subpixel level, but only if the specific scaling recommendations and limitations reported in this study are taken into account.
Abstract: One of the most rapidly growing applications of remotely sensed data is the derivation of landscape pattern metrics for the assessment of land cover condition and landscape change dynamics. The availability of a wide variety of sensors allows for characterisation of land cover at multiple spatial scales, and increases the need for practical scaling techniques that permit the comparison of pattern estimates across different spatial resolutions. Previous research has reported on scaling functions describing the variations of different landscape pattern metrics with spatial resolution; this may be particularly useful in downscaling spatial pattern characteristics, but no quantitative results or independent validation have been reported yet in this respect. We analysed a wide set of landscape data derived from remotely sensed images covering different study areas, sensor spatial resolutions, and classification approaches (pixel-based and object-based), which were aggregated to coarser resolutions through majority filters. We considered eight landscape pattern metrics for which predictable scaling functions have been reported, and compared the subpixel estimates provided by those scaling functions (when fitted to the metric values for different ranges of spatial resolution above the pixel level) with the true value of the metric at the subpixel resolution. We found that for metrics like mean patch size, landscape shape index or edge length, quite accurate subpixel estimates were achieved in all the datasets, even for relatively large downscaling factors. However, the opposite was the case for several of the metrics for which a predictable scaling behaviour had been previously described. The most accurate subpixel estimates were obtained when only a narrow range of spatial resolutions (closest to the subpixel resolution) was used to fit the scaling function, suggesting that the scaling functions are not fully scale invariant. We also found that the performance of available scaling functions is much lower in object-based data (in comparison with per-pixel classified data) for ranges of spatial resolution below the characteristic minimum mapping unit of the interpreted or segmented image. We conclude that scaling functions may be useful and reasonably accurate for estimating pattern metrics at the subpixel level, but only if the specific scaling recommendations and limitations reported in this study are taken into account.

Journal ArticleDOI
TL;DR: The ability of HDM to accurately and reproducibly measure displacement and regional function in the beating heart and the repeatability of using this method to compute RSW was assessed.

Patent
10 Oct 2007
TL;DR: In this article, the area and number of subpixels are adjusted in accordance with the visual sensitivity or luminosity required, and the area of red (R) and blue (B) subpixels which are relatively low in luminosity is set to be about two times greater than the areas of green (G) and white (W) subpixel that are relatively high in luminities.
Abstract: In a color display device, when using white (W) sub-pixels in addition to subpixels of red (R) and green (G) plus blue (B) without increasing a wiring line number, the per-color pixel number in a unit area decreases so that the image resolution is deteriorated. The area and number of subpixels are adjusted in accordance with the visual sensitivity or luminosity required. Practically, the area of red (R) and blue (B) subpixels which are relatively low in luminosity is set to be about two times greater than the area of green (G) and white (W) subpixels that are relatively high in luminosity while letting the number of green (G) and white (W) subpixels be twice the number of red (R) and blue (B) subpixels. A larger subpixel is configured from a plurality of unit subpixels. A smaller subpixel is formed of a one unit subpixel.

Journal ArticleDOI
01 Feb 2007-Micron
TL;DR: A new approach providing super resolved images exceeding the geometrical limitation given by the detector pixel size of the imaging camera is presented, involving the projection of periodic patterns on top of the sample which are then investigated under a microscope.

Proceedings ArticleDOI
12 Nov 2007
TL;DR: It is argued that the discretization error in pixel-level background models is also responsible for some of the false positives and developed a method based on subpixel edges whose background is thus highly selective and has been tested on a wide range of videos.
Abstract: We propose an approach to model the background of images in a video sequence based on subpixel edge map. This work is motivated by the observation that intensity based background models are sensitive to changes in illumination and camera parameters, e.g., gain control. In addition, the false positive rate is higher due to accidental alignment of figure intensities with the background model. Background models of edge maps, however, are more localized and thus reduce the likelihood of accidental alignment. We argue that the discretization error in pixel-level background models is also responsible for some of the false positives and develop a method based on subpixel edges whose background is thus highly selective. This method models the edge position and orientation using a Mixture of Gaussians model. This approach has been tested on a wide range of videos and the resulting background models are a much more selective figure-ground segregation.

Journal ArticleDOI
TL;DR: In this paper, the pixel swapping algorithm was used for predicting subpixel landcover distribution. But, the authors found that the form of this relationship depends upon the simulation model and the experimental results showed that pixel swapping increased classification accuracy compared with the initial random allocation of subpixels.
Abstract: This study investigates the “pixel-swapping” optimization algorithm proposed by Atkinson for predicting subpixel landcover distribution. Two limitations of this method are assessed: the arbitrary spatial range value and the arbitrary exponential model for characterizing spatial autocorrelation. Various alternative weighting functions are evaluated. For this assessment, two different simulation models are employed to develop spatially autocorrelated binary class raster maps. These rasters are then resampled to generate sets of representative medium-resolution class maps. Prior to conducting the subpixel allocation, the relationship between cell resolution and spatial autocorrelation, as measured by Moran’s I, is evaluated. It is discovered that the form of this relationship depends upon the simulation model. For all tested weighting functions (Nearest Neighbor, Gaussian, Exponential, and IDW), the pixel swapping method increased classification accuracy compared with the initial random allocation of subpixels. Nearest Neighbor allocation performs as well as the more complex models of spatial structure.

Journal ArticleDOI
TL;DR: The SNR is least sensitive to vertical subpixel misalignments on the detector with a Hadamard-matrix-based code, and the increased sensitivity of a spectrometer using a coded aperture instead of a slit is demonstrated.
Abstract: We experimentally evaluate diverse static independent column codes in a coded aperture spectrometer. The performance of each code is evaluated based on the signal-to-noise ratio (SNR), defined as the peak value in the spectrum to the standard deviation of the background noise, as a function of subpixel vertical misalignments. Among the code families tested, an S-matrix-based code produces spectral reconstructions with the highest SNR. The SNR is least sensitive to vertical subpixel misalignments on the detector with a Hadamard-matrix-based code. Finally, the increased sensitivity of a spectrometer using a coded aperture instead of a slit is demonstrated.

01 Jan 2007
TL;DR: In this article, the inverse projection matrices for which a rigorous resampling is pro- posed are pro-posed to avoid aliasing in the ortho-rectified images, where look directions are linearly corrected to compensate for attitude drifts, and sensor orientation uncertain ties are accounted for.
Abstract: We describe a procedure to accurately measure ground deformations from optical satellite images. Precise orthorectification is obtained owing to an optimized model of the imaging system, where look directions are linearly corrected to compensate for attitude drifts, and sensor orientation uncertain- ties are accounted for. We introduce a new computation of the inverse projection matrices for which a rigorous resampling is pro- posed. The irregular resampling problem is explicitly addressed to avoid introducing aliasing in the ortho-rectified images. Image reg- istration and correlation is achieved with a new iterative unbiased processor that estimates the phase plane in the Fourier domain for subpixel shift detection. Without using supplementary data, raw images are wrapped onto the digital elevation model and coregis- tered with a 1/50 pixel accuracy. The procedure applies to images from any pushbroom imaging system. We analyze its performance using Satellite pour l'Observation de la Terre (SPOT) images in the case of a null test (no coseismic deformation) and in the case of large coseismic deformations due to the Mw 7.1 Hector Mine, California, earthquake of 1999. The proposed technique would also allow precise coregistration of images for the measurement of surface displacements due to ice-flow or geomorphic processes, or for any other change detection applications. A complete soft- ware package, the Coregistration of Optically Sensed Images and Correlation, is available for download from the Caltech Tectonics Observatory website.

Patent
John K. Roberts1, Chenhua You1
30 Aug 2007
TL;DR: In this article, the backlight controller can be configured to emit the first and second colors of light at the same time to generate a first image component including a combination of the first colour image data and the second color image data.
Abstract: A liquid crystal display (LCD) device includes a pixel array including a plurality of pixels configured to display an image. The plurality of pixels respectively include a first subpixel configured to display first color image data, and a second subpixel configured to display second and third color image data. The LCD device may further include a backlight configured to emit the first, second, and/or third colors of light, and a backlight controller. The backlight controller may be configured to activate the backlight to emit the first and second colors of light at a same time to generate a first image component including a combination of the first color image data and the second color image data, and to separately emit the third color of light at a different time than the first and second colors of light to generate a second image component including the third color image data. The pixel array may be configured to display the first and second image components to provide a single image frame. Related devices and methods of operation are also discussed.

Journal ArticleDOI
TL;DR: A new two-step phase-shifting fringe projection profilometry is proposed, where the slowly variable background intensity of fringe patterns is removed by the use of an intensity differential algorithm.
Abstract: A new two-step phase-shifting fringe projection profilometry is proposed. The slowly variable background intensity of fringe patterns is removed by the use of an intensity differential algorithm. The high-resolution differential algorithm is achieved based on global interpolation of fringe gray level on a subpixel scale. Compared with the traditional three- or four-step phase-shifting method, the profile measurement is sped up with this approach. Computer simulation and experimental performance are evaluated to demonstrate the validity of the proposed measurement method. The experimental results compared with those of the four-step phase-shifting method are presented.

Proceedings Article
01 Sep 2007
TL;DR: This work proposes a filter design method for subpixel rendering that uses simpler model for image perception and obtains the filter directly in the spatial domain, and experimentally demonstrates that the proposed filter provides smooth edges, while reducing color fringing effect.
Abstract: The subpixel rendering is attractive in that it improves effective resolutions of displays by processing at the subpixel level. But it lies on a risk of chrominance error called color fringing effect while restoring the degraded shape of restrictive resolution. We propose a filter design method for subpixel rendering. We first generate a virtual image model, which describes how human visual system perceives color at each subpixel position. Then, we derive the filter that minimizes the difference between the original image and the corresponding virtual image. While other algorithm is achieved in frequency domain, our algorithm use simpler model for image perception and obtain the filter directly in the spatial domain. We experimentally demonstrate that the proposed filter provides smooth edges, while reducing color fringing effect.

Patent
26 May 2007
TL;DR: In this paper, the authors proposed a method for continuous tracking without noticeable skips in the case of physical changes in head position, which involves reducing the intensities of all subpixels of the matrix screen in order to form intensity focuses for subpixel groups behind barrier elements, which comprise a number n of subpixels including a subpixel reserve, in the image lines.
Abstract: It is known practice for lateral changes in the head position to be taken as a basis for relocation which redistributes intensities of individual subpixels over adjacent subpixels of the same colour in stages. The relatively great distance between subpixels of the same colour value results in increased asymmetry between the vertical and horizontal resolution of the stereo image when the intensity of individual subpixels has its focus relocated in this manner, however. For continuous tracking without noticeable skips in the case of physical changes in head position, the inventive method involves reducing the intensities of all subpixels of the matrix screen in order to form intensity focuses for subpixel groups behind barrier elements, which comprise a number n of subpixels, including a subpixel reserve, in the image lines. In the case of parallel alterations, these intensity focuses are then displaced by a constant absolute value continuously through directly adjacent subpixels and also through subpixel group boundaries with different stereo image views. Distance changes involve the intensity focuses being increasingly widened or compressed relative to the screen edges. The intensities of the individual subpixels can be altered by means of simple multiplication by standardized constant or variable intensity factors which can be ascertained as a function of motion.

Journal ArticleDOI
TL;DR: It is shown both theoretically and by computer simulation that the choice of regularly spaced subpixel shifts for the LR images tends to maximize the robustness and minimize the error of reconstruction of the HR image.
Abstract: The technique of reconstructing a higher-resolution (HR) image of size ML×ML by digitally processing L×L subpixel-shifted lower-resolution (LR) copies of it, each of size M×M, has now become well established. This particular digital superresolution problem is analyzed from the standpoint of the generalized sampling theorem. It is shown both theoretically and by computer simulation that the choice of regularly spaced subpixel shifts for the LR images tends to maximize the robustness and minimize the error of reconstruction of the HR image. In practice, since subpixel-level control of LR image shifts may be nearly impossible to achieve, however, a more likely scenario, which is also discussed, is one involving random subpixel shifts. It is shown that without reasonably tight bounds on the range of random shifts, the reconstruction is likely to fail in the presence of even small amounts of noise unless either reliable prior information or additional data are available.

Journal ArticleDOI
TL;DR: In this paper, the point spread function of double-aperture digital holography is determined and an experimental method for the determination of this shift with subpixel accuracy is given.
Abstract: The resolution of digital holography as an optical imaging system is described by the point spread function of the system. Here the point spread function of double-aperture digital holography is determined. It promises the possibility of a resolution increase by the use of synthetic apertures, where we combine the digital holograms of two CCD arrays in one large hologram and reconstruct, or we superpose coherently the two reconstructed wave fields after a proper shift. An experimental method for the determination of this shift with subpixel accuracy is given. Furthermore, experimental results on numerically reconstructed wave fields from synthetic holograms stemming from two mutually shifted digital holograms of the same scene are presented.

Patent
02 Mar 2007
TL;DR: A display panel comprises substantially a plurality of a subpixel repeating group comprising an even number of subpixels in a gate direction, wherein at least one set of adjacent column of same colored subpixels share image data from a single driver upon the display panel.
Abstract: Dot inversion schemes are disclosed on novel display panel layouts with extra drivers. A display panel comprises substantially a plurality of a subpixel repeating group comprising an even number of subpixels in a gate direction, wherein at least one set of adjacent column of same colored subpixels share image data from a single driver upon the display panel.