Abstract: In this paper, a semiblind algorithm is presented for the estimation of sparse multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) channels. An analysis of the second-order statistics of the signal that was received through a sparse MIMO channel is first conducted, showing that the correlation matrices of the received signal can be expressed in terms of the most significant taps (MSTs) of the sparse channel. This relationship is used to derive a blind constraint for the effective channel vector that corresponds to the MST position. The blind constraint is then combined with the training-based least square criterion to develop a semiblind approach for the estimation of MSTs of the sparse channel. A signal perturbation analysis of the proposed approach is conducted, showing that the new semiblind solution is not subject to the signal perturbation error when the sparse channel is a decimated version of a full finite impulse response channel. Furthermore, the proposed sparse semiblind algorithm has been extended for the estimation of channels in the upsampling domain for MIMO-OFDM systems with pulse shaping. A number of computer-simulation-based experiments for various sparse channels are carried out to confirm the effectiveness of the proposed semiblind approach.

Abstract: Multispectral demosaicking, which estimates full multispectral images from raw data observed using a single image sensor with a color filter array (CFA), is a challenging task because each spectral component is severely undersampled. In this paper, we propose a novel multispectral demosaicking algorithm. We extend existing upsampling algorithms to adaptive kernel upsampling algorithms using an adaptive kernel as a spatial weight and apply them to multispectral demosaicking. We also propose a new CFA and a direct adaptive kernel estimation from the raw data of the proposed CFA. Experimental results with real multispectral images demonstrate the effectiveness of the proposed algorithm.

Abstract: The main operational mode of the European Space Agency's upcoming Sentinel-1 operational satellite will be the Terrain Observation by Progressive Scans (TOPS) imaging mode. This paper presents a very efficient wavenumber domain processor for the processing of TOPS mode data. In particular, a novel signal transform, called a moving band chirp Z-transform, is introduced in order to allow the entire azimuth aperture to be focused simultaneously without any need for temporary unaliasing, which requires upsampling, or subaperture processing.

Abstract: In this paper, we introduce a novel and cost effective approach to calibrate the geometric properties of a far-infrared (IR) sensor. We further demonstrate that fully automatic sensor-to-sensor calibration is feasible in a setup involving a laser range scanner, IR cameras as well as conventional cameras. The calibration result then serves as a basis for upsampling range measurements to the resolution of the IR or visible-light camera images. Since our approach allows to rely on IR information instead of visible-light information for upsampling, bad light conditions or even no visible light at all are no limitation. From a practical point of view, we only require one calibration board of relatively small size which facilitates application in outdoor environments and further allows seamless integration of the IR camera in an existing multi-sensor platform. Our experimental results demonstrate that IR images are particularly useful to obtain reasonable depth information for living objects, when visible-light cameras are either blind or require impractical exposure times. In fact, our approach provides a convenient solution to IR camera calibration and integration, an issue which is particularly important in scenarios where sensors are not permanently mounted on vehicles and consequently require on-site adjustment and calibration.

Abstract: This paper proposes an efficient structure for implementing a linear-phase finite-impulse-response (FIR) filter of an arbitrary order N for the sampling-rate conversion by a rational factor of L/M , where L(M) is the integer upsampling (down-sampling) factor to be performed before (after) the actual filter. In this implementation, the coefficient symmetry of the linear-phase filter is exploited as much as possible and the number of delay elements is kept as low as possible while utilizing the following facts. When increasing (decreasing) the sampling rate by a factor of L(M), only every Lth input sample has a nonzero value (only every M th output sample has to be evaluated). In this way, the number of required multiplications per output sample is reduced approximately by a factor of two compared with the conventional polyphase implementation. The proposed implementation is first illustrated using two examples. Based on these examples, guidelines are then given on how to efficiently realize an Nth-order linear-phase FIR filter for a sampling-rate converter having an arbitrary rational conversion factor L/M. Finally, the implementation complexity of the proposed approach is evaluated and some examples are included, showing the efficiency of the proposed implementation compared with other existing ones.

Abstract: Nowadays, mobile video streaming enables people to access digital content, such as online TV shows, music videos, sports reports, and news programs, anytime, anywhere. However, current streaming services in mobile networks are subject to the available wireless bandwidth shared among many users and can only provide videos with limited resolutions. Moreover, on recently developed high-resolution mobile devices, such as iPhone, Google Nexus One, Nokia N97, and SonyEricsson X10, the resolution of video streaming is much lower than the devices can actually support. As a result, existing video upsampling schemes usually introduce visual artifacts. In response to the above problem, we bridge the resolution gap between streaming videos and client screens, and propose a novel upsampling-based system architecture, called MobiUP, to enable high-quality video streaming onto mobile devices. To avoid modifying existing codecs for video streaming, MobiUP upsamples videos with decoded frames and appends a limited amount of metadata to the streaming videos for facilitating high-quality and real-time conversion from low resolution to high fullscreen resolution on the client side. In other words, the proposed upsampling architecture complements current systems. Therefore, MobiUP is generic and flexible, and it can be implemented easily on mobile devices for practical use. The implementation results demonstrate that, although the appended metadata is less than 8% of the total transmitted data, it improves the quality of the upsampled video significantly. Meanwhile, the computation time of MobiUP Client is close to that of bilinear upsampling algorithms implemented on mobile devices.

Abstract: A new simple approach to the design of digital algorithm for simultaneous reactive-power and frequency estimations of local system is presented. The algorithm is derived using the weighted-least-square method. During the algorithm derivation, a pure sinusoidal voltage model was assumed. Cascade finite-impulse-response (FIR) comb digital filters are used to minimize the noise effect and to eliminate the presence of harmonics effect. The most important point of this paper is the mathematical model that transforms the problem of estimation into an overdetermined set of linear equations. The investigation was simplified because the total similarity to the state of the problem of the active-power and frequency estimations was noticed. The only difference is the adaptive phase shifter applied to the voltage signal. In addition, coefficient-sensitivity problems of the large-order FIR comb cascade structure are overridden by using a multirate (decimation) digital signal processing technique. Even more, by using antialiasing filters, the parameter estimation accuracy is improved. The effectiveness of the proposed techniques is demonstrated by both simulation and experimental results. The algorithm shows a very high level of robustness, as well as high measurement accuracy over a wide range of frequency changes.

Abstract: A method includes receiving an image having a first resolution and generating an upsampled image having a second resolution based on the image. A multi-dimensional data structure corresponding to a multi-dimensional image space is generated from the upsampled image. Each node of the data structure is determined based on a weighted sum of values of one or more pixels in the upsampled image. Each of the one or more pixels corresponds to a pixel in the received image and is located within a region of the image space having a vertex defined by the node. A filter modifies the values of the nodes and a second upsampled image is generated based on the modified values of the nodes. Each pixel of the second upsampled image not corresponding to a pixel in the received image is determined based on a weighted sum of the modified values of one or more nodes.

Abstract: We propose a fast algorithm for solving the inverse problem of resolution enhancement (superresolution). Robustness is achieved by a non-linear regularizer and a method based on variable splitting is used to obtain an equivalent linear formulation. Special attention is paid to fast implementation using the Fourier transform. In particular, we show that a degradation operator (downsampling) can be implemented in the frequency domain and that all computations can be performed very efficiently without losing robustness. To our knowledge, this is the first attempt towards a very fast SR algorithm, which retains favorable edge-preserving properties of non-linear regularizers.

Abstract: An image processing module performs efficient image enhancement according to a multi-scale energy minimization process. One or more input images are progressively downsampled to generate a pyramid of downsampled images of varying resolution. Starting with the coarsest downsampled image, a label map is generated that maps output pixel positions to pixel positions in the downsampled input images. The label map is then progressively upsampled. At each upsampling stage, the labels are refined according to an energy function configured to produce the desired enhancements. Using the multi-scale energy minimization, the image processing module enhances image via hole-filling and/or super-resolution.

Abstract: This paper describes a series of new results outlining equivalences between certain “rewirings” of filterbank system block diagrams, and the corresponding actions of convolution, modulation, and downsampling operators. This gives rise to a general framework of reverse-order and convolution subband structures in filterbank transforms, which we show to be well suited to the analysis of filterbank coefficients arising from subsampled or multiplexed signals. These results thus provide a means to understand time-localized aliasing and modulation properties of such signals and their subband representations - notions that are notably absent from the global viewpoint afforded by Fourier analysis - as well as signal recovery from sampled sequences based on their filterbank characterizations. The utility of filterbank rewirings is demonstrated by the closed-form analysis of signals subject to degradations such as missing data, spatially or temporally multiplexed data acquisition, or signal-dependent noise, the likes of which are often encountered in practical signal processing applications.

Abstract: The ability to produce dynamic Depth of Field effects in live video streams was until recently a quality unique to movie cameras. In this paper, we present a computational camera solution coupled with real-time GPU processing to produce runtime dynamic Depth of Field effects. We first construct a hybrid-resolution stereo camera with a high-res/low-res camera pair. We recover a low-res disparity map of the scene using GPU-based Belief Propagation and subsequently upsample it via fast Cross/Joint Bilateral Upsampling. With the recovered high-resolution disparity map, we warp the high-resolution video stream to nearby viewpoints to synthesize a light field towards the scene. We exploit parallel processing and atomic operations on the GPU to resolve visibility when multiple pixels warp to the same image location. Finally, we generate dynamic Depth of Field effects from the synthesized light field rendering. All processing stages are mapped onto NVIDIA’s CUDA architecture. Our system can produce Depth of Field effects with arbitrary aperture sizes and focal depths for the resolution of 640×480 at 15 fps.

Abstract: An image processing module infers depth from a stereo image pair according to a multi-scale energy minimization process. A stereo image pair is progressively downsampled to generate a pyramid of downsampled image pairs of varying resolution. Starting with the coarsest downsampled image pair, a disparity map is generated that reflects displacement between corresponding pixels in the stereo image pair. The disparity map is then progressively upsampled. At each upsampling stage, the disparity labels are refined according to an energy function. The disparity labels provide depth information related to surfaces depicted in the stereo image pair.

Abstract: A device and a method of up-sampling low resolution depth data is described, in particular in the form of a range map or a disparity map of stereo content, comprising the following successive steps: up-scaling the low resolution depth data to the desired resolution using a nearest neighbour interpolation to receive an up-scaled disparity map, detecting the horizontal and vertical bounds of each pixel of a high resolution colour image based on intensity differences, wherein the low resolution depth data correspond to the high resolution colour image, combining the up-scaled disparity map and the detected vertical and horizontal bounds by applying an averaging filter among an arbitrary shaped region by the utilization of horizontal and vertical integral data of the up-scaled disparity map to receive a high resolution disparity map.

Abstract: An apparatus for processing an audio signal is provided. The apparatus comprises a signal processor (110; 205; 405) and a configurator (120; 208; 408). The signal processor (110; 205; 405) is adapted to receive a first audio signal frame having a first configurable number of samples of the audio signal, Moreover, the signal processor (110; 205; 405) is adapted to upsample the audio signal by a configurable upsampling factor to obtain a processed audio signal. Furthermore, the signal processor (110; 205; 405) is adapted to output a second audio signal frame having a second configurable number of samples of the processed audio signal. The configurator 120; 208; 408) is adapted to configure the signal processor (110; 205; 405) based on configuration information such that the configurable upsampling factor is equal to a first upsampling value when a first ratio of the second configurable number of samples to the first configurable number of samples has a first ratio value. Moreover, the configurator ( 120; 208; 408) is adapted to configure the signal processor (110; 205; 405) such that the configurable upsampling factor is equal to a different second upsampling value, when a different second ratio of the second configurable number of samples to the first configurable number of samples has a different second ratio value. The first or the second ratio value is not an integer value.

Abstract: A programmable logic device can be configured as a fractional rate resampling filter capable of performing downsampling prior to upsampling without modifying the overall filter response. Input data may be received at a first sample rate and may be downsampled to generate downsampled data. Portions of the downsampled data may be respectively output to different filtering paths. Each filtering path may include a cluster of filter components that corresponds to different subfilters of the overall filter response and may be operable to receive and process the different portions of the downsampled data. Outputs of each cluster may be combined to generate output data at a second sample rate. The resampling filter structure can reduce the number of multiplier circuits used by allowing time-division multiplexing among different filter components.

Abstract: The invention provides an edge self-adaptive image amplification method based on non-downsampling Contourlet conversion, comprising the following steps: (1) inputting original images, setting resolution ratio of target images, and determining amplification proportional coefficient of the images; (2) carrying out non-downsampling Contourlet conversion on the original images to obtain directional subband coefficient image of transform domain; (3) amplifying the directional subband coefficient image to be the object resolution by adopting the directional self-adaptive interpolation method; (4) estimating the interpolation direction of each point to be interpolated of the target images according to the amplified directional subband coefficient image; (5) adopting the directional self-adaptiveinterpolation method to obtain the pixel value of the point to be interpolated according to the interpolation direction of the target images point to be interpolated; and (6) outputting ultimate amplified image. The invention realizes interpolation at any direction; the edges of the amplified images have high smooth level; and entire visual effect of the images is favorable, thus being applicableto proportional amplification of grey or colorful images.

Abstract: Recently, the probabilistic motion field was proposed for super-resolution reconstruction (SRR). In the interpolation step of SRR, a missing pixel can be estimated by the weighted average of neighboring pixels, which are weighted by the errors with the missing pixel. However, the errors are far from true values due to the approximated missing pixel in calculating the errors. Hence, in this paper, we propose a linear motion model to better approximate the errors, which results in a better interpolation quality. Experimental results show that a gain of 0.6 dB in PSNR is achievable using this linear motion model, and only a small number of neighboring pixels have to be used for fast interpolation/upsampling.

Abstract: Current active 3D range sensors, such as time-of-flight cameras, enable acquiring of range maps at video frame rate. Unfortunately, the resolution of the range maps is quite limited and the captured data are typically contaminated by noise. We therefore present a simple pipeline to enhance the quality as well as improve the spatial and depth resolution of range data in real time. To improve the spatial resolution of range data, we first upsample the depth information with the data from high resolution video camera. And then, a new strategy is utilized to increase the sub-pixel accuracy. We show that these techniques can greatly improve the reconstruction quality, boost the resolution of the range data to that of video sensor while achieving high computational efficiency for a real-time application.

Abstract: A full spectrum modulator processes a plurality of CATV channels from separate paths. Each path has (i) a first filter for pulse shaping an input channel signal and upsampling a channel frequency thereof, (ii) an interpolator for interpolating the output of the first filter to a common sample rate, and (iii) a decimator for centering the output of the interpolator on a predetermined channel bandwidth. An IDFT processor receives channel signal outputs from the decimators. A polyphase filter bank receives IDFT processed parallel channel signals from the IDFT processor. A commutator converts the processed parallel channel signals from the polyphase filter bank to a single stream of data. A second filter upsamples the single stream of data to a fixed output sampling rate and low pass filters alias signals therefrom. Both standard and harmonically related carrier CATV channel frequency plans are accommodated.

Abstract: A high accuracy rotation angle estimation algorithm based on Local Upsampling Fourier Transform (LUFT) is developed in this paper. The LUFT uses a hierarchical strategy to estimate the rotation, which consists of a transformation of rotation to translation, a fast coarse rotation estimation and a robust refinement stage as well. The coarse rotation is estimated through the conventional Phase Only Correlation (POC), then, it is refined by the resampling technique within a local neighborhood in frequency domain. Furthermore, as will be shown in many experiments, the LUFT can achieve high accuracy rotation estimation, where the accuracy is tunable to some extent. Specially, it is efficient and robust to noise.

Abstract: We present a novel edge preserved interpolation scheme for fast upsampling of natural images. The proposed piecewise hyperbolic operator uses a slope-limiter function that conveniently lends itself to higher-order approximations and is responsible for restricting spatial oscillations arising due to the edges and sharp details in the image. As a consequence the upsampled image not only exhibits enhanced edges, and discontinuities across boundaries, but also preserves smoothly varying features in images. Experimental results show an improvement in the PSNR compared to typical cubic, and spline-based interpolation approaches.

Abstract: The invention discloses an image autoregressive interpolation method based on edge detection, and the method is mainly used for solving the problem of high complexity of the existing autoregressive interpolation technique. The method comprises the following steps: carrying out one quarter of downsampling on original images, carrying out edge detection on the downsampling images, approximately obtaining the edge detection images of the to-be interpolated recovery images according to the edge detection images of the downsampling images; classifying the to-be-interpolated pixels of the to-be-interpolated recovery images into to-be-interpolated pixels in smooth area and edge area, adopting bicubic to carry out interpolation on the to-be-interpolated pixels in the smooth area, adopting the autoregressive interpolation method to interpolate the to-be-interpolated pixels in the edge area; and obtaining the image after interpolation. On the premise of ensuring the visual effects of the images, the method in the invention can be utilized to carry out amplification, denoising, mending, deinterlacing and compression on the images.

Abstract: PROBLEM TO BE SOLVED: To reduce a total number of pixels of transmission data while maintaining composite image quality.SOLUTION: An image transmission method includes: a step of downsampling a multi-viewpoint image based on a reduction rate and outputting a low-resolution image; a step of coding the low-resolution image; a step of coding a high resolution depth map; a step of decoding low-resolution image code data; a step of decoding high-resolution depth map code data; a step of setting an inter-viewpoints correspondence relation by obtaining a corresponding point at small number pixel precision at the other view point of each pixel with depth information of the pixel obtained by the high-resolution multi-viewpoint depth map; a step of projecting a three-dimensional projection point to the other view point and obtaining an inter-viewpoints correspondence relation; a step of upsampling while referring to a small number pixel value at the other view point based on the inter-viewpoints correspondence relation and forming a high resolution image from the low-resolution image; and a step of synthesizing images at an arbitrary view point from the high resolution image and high resolution depth map.

Abstract: This article presents a new indirect identification method for continuous-time systems able to resolve the problem of fast sampling. To do this, a Subspace IDentification Down-Sampling (SIDDS) approach that takes into consideration the intermediate sampling instants of the input signal is proposed. This is done by partitioning the data set into m subsets, where m is the downsampling factor. Then, the discrete-time model is identified using a based subspace identification discrete-time algorithm where the data subsets are fused into a single one. Using the algebraic properties of the system, some of the parameters of the continuous-time model are directly estimated. A procedure that secures a prescribed number of zeros for the continuous-time model is used during the estimation process. The algorithm's performance is illustrated through an example of fast sampling, where its performance is compared with the direct methods implemented in Contsid.

Abstract: The interpolation of contour pixels, with splines, of an order greater than or equal to two, usually causes oscillations that do not fit the original shape. To overcome this we propose using a least squares filter before carrying out the interpolation. This results in a good compromise between the smoothness of the curve and the best fit to the original contour. Representing the contour with a continuous model instead of a discrete model has many advantages for carrying out calculations, as for example the contour curvature, which involves first and second order derivatives, as well as operations that are not well defined in the discrete world. We also present a new way of calculating FIR approximations to filters based on B-splines. The great advantage of this approximation in the case of least squares filter is that it does not need downsampling. This property makes it invariant to translations, and this is very important in classification tasks.

Abstract: We consider the problem of upsampling a low-resolution depth map generated by a range camera, by using information from one or more additional high-resolution vision cameras. The goal is to provide an accurate high resolution depth map from the viewpoint of one of the vision cameras. We propose an algorithm that first converts the low resolution depth map into a depth/disparity map through coordinate mappings into the coordinate frame of one vision camera, then classifies the pixels into regions according to whether the range camera depth map is trustworthy, and finally refine the depth values for the pixels in the untrustworthy regions. For the last refinement step, both a method based on graph cut optimization and that based on bilateral filtering are examined. Experimental results show that the proposed methods using classification are able to upsample the depth map by a factor of 10 x 10 with much improved depth details, with significantly better accuracy comparing to those without the classification. The improvements are visually perceptible on a 3D auto-stereoscopic display.

Abstract: PROBLEM TO BE SOLVED: To enhance frequency resolution while enhancing resolution in a time range to be measured, and reduce an operation amount by reducing sample number through decrease of a sampling frequency in Fourier transform.SOLUTION: The device executes steps of using: a modulator 5 to apply frequency conversion to a received signal; an A/D converter 61 to convert a frequency converted signal into a digital signal by oversampling through an analog filter 7; a digital BPF 62 to extract a component equivalent to an intended frequency bandwidth Δf; a downsampling part 63 to decrease a sampling frequency of the extracted signal to a lowest frequency bandwidth through conversion; a signal clipping gate 11 to clip out a digital data column from the downsampling part 63 within an intended duration, after the downsampling; a zero addition part 12 to add zero data so as to satisfy frequency resolution; and an FFT processing part 13 to apply fast Fourier transform to the zero-data-added digital data column.

Abstract: A signal processor selects an element from a rendition of a signal at a first level of quality to upsample into multiple elements of a rendition of the signal at a second (higher) level of quality. The signal processor produces a metric based on settings of elements in a vicinity of the selected element in the rendition of the signal at the first level of quality. The metric defines a boundary between a first set of elements in a vicinity of the selected element and a second set of elements in a vicinity of the selected element. The signal processor utilizes the metric to calculate settings for the multiple elements in the signal at the second level of quality. A location and orientation of the boundary with respect to the selected element depends on the settings of elements in the vicinity of the selected element.