nils-herrmann/clean_scirepeval huggingface dataset:
The vector split-radix algorithm for 2D DHT

A decimation-in-frequency vector split-radix algorithm is proposed to decompose an N*N 2D discrete Hartley transform (DHT) into one (N/2)*(N/2) DHT and twelve (N/4) DHTs. The proposed algorithm possesses the in-place property and needs no matrix transpose. Its computational structure is very regular and is simpler than those of all existing nonseparable 2D DHTs.
A low complexity algorithm for detecting rotational symmetry based on the Hough transform technique

The Hough transform technique has been applied to detect rotational symmetry by Yip et al. (1994). He proposed an O(N/sup 3/) algorithm, where N is the number of edge points in the input image, to extract global or local features of rotational symmetry in the presence of noise and occlusion. In this paper, we follow the Yip et al. concept and design a simple and efficient algorithm, which can detect the rotational symmetry in O(N/sup 2/) time. Some simulation results of the new proposed algorithm are also given.
Image Feature Extraction in Encrypted Domain With Privacy-Preserving SIFT

Privacy has received considerable attention but is still largely ignored in the multimedia community. Consider a cloud computing scenario where the server is resource-abundant, and is capable of finishing the designated tasks. It is envisioned that secure media applications with privacy preservation will be treated seriously. In view of the fact that scale-invariant feature transform (SIFT) has been widely adopted in various fields, this paper is the first to target the importance of privacy-preserving SIFT (PPSIFT) and to address the problem of secure SIFT feature extraction and representation in the encrypted domain. As all of the operations in SIFT must be moved to the encrypted domain, we propose a privacy-preserving realization of the SIFT method based on homomorphic encryption. We show through the security analysis based on the discrete logarithm problem and RSA that PPSIFT is secure against ciphertext only attack and known plaintext attack. Experimental results obtained from different case studies demonstrate that the proposed homomorphic encryption-based privacy-preserving SIFT performs comparably to the original SIFT and that our method is useful in SIFT-based privacy-preserving applications.
High Speed Video Compression Testbed

This paper proposes a parallel processing architecture for a video compression testbed. Experiments for video coding algorithms can be performed and evaluated under this parallel processing architecture. The features of this testbed include (1) simulations of various hardware architectures, (2) test of specialized video compression circuits, and (3) testing ASICs for embedded applications as direct replacement of algorithms that have been certified. We illustrate its implementation, performance evaluation and benchmarking via JPEG/MPEG applications.
Background Adjustment and Saturation Enhancement in Ancient Chinese Paintings

This work presents a color enhancement scheme to virtually restore ancient Chinese paintings in electronic form. Two degradations result in color contrast loss in ancient Chinese paintings: paper aging and pigment fading. The proposed enhancement scheme comprises two subsequent methods: background adjustment and saturation enhancement. The former method, based on the Von Kries color conversion in the CIE xyY color space, retrieves the original color of the paint paper by modifying colors based on their similarity to the background color. The proposed saturation enhancement method makes colors more vivid and bright, and also improves the image contrast
Design and application of discrete-time fractional Hilbert transformer

In this paper, the design problems and applications of the fractional Hilbert transformer (FHT) are investigated. First, the conventional Hilbert transformer is generalized to FHT. Its corresponding analytic signal is also defined to construct a single-sideband (SSB) signal for saving communication bandwidth. Then, several methods are presented to design finite and infinite impulse response FHTs including the Hilbert transformer-based method, all-pass filter-based method, optimization methods, etc. Next, we propose a secure SSB communication in which the fractional order of FHT is used as a secret key for demodulation. Finally, the two-dimensional FHT is used to detect edges or corners of digital images.
A class of efficient recursive quadrature mirror filters for subband coding

A class of recursive quadrature mirror filters (QMFs) of the form H(Z)=N(Z)/D(Z/sup 2/) is proposed for subband coding. These filters can be efficiently designed with the iterative Remez exchange algorithm. Simple modifications are made to the Pei (see  1989), Liang, McClellan, and Parks computer program for designing these recursive QMF filters efficiently. The resulting filters totally eliminate the aliasing terms and can achieve almost perfect magnitude reconstruction, with -131.5-dB distortion. A design example is presented to show the effectiveness of this approach.
Commuting operator of offset linear canonical transform and its applications

Linear canonical transform (LCT) is an attractive and useful tool in optics and signal processing. In previous work, a generalization of the LCT with two extra parameters, called offset LCT (OLCT), has been developed. In this paper, a different definition of OLCT is proposed, which has a more concise form of inverse transform. We find a linear operator that commutes with the proposed OLCT. We prove that the commuting operator and the proposed OLCT have the same set of eigenfunctions with different eigenvalues. We also derive the discrete version of the commuting operator to develop a discrete OLCT. The proposed discrete OLCT has perfect reversibility property.
Novel error concealment method with adaptive prediction of abrupt and gradual scene changes

In this paper, the impact of scene change on the conventional error concealment method is addressed and a novel error concealment method is proposed to improve the insufficiency of the conventional temporal error concealment algorithm due to the occurrence of scene changes. Combined with the low complexity scene change detection algorithm using macroblock type information, the corrupt blocks resulting from bit errors are concealed either temporally or spatially depending on whether or not an abrupt scene change is found. In the case of a gradual scene change, a novel error concealment method of interpolation and extrapolation is proposed to utilize the linear property of a gradual scene change sequence, and effectively reduce the concealment error compared with the conventional algorithm. A great improvement of about 3 to 5 dB PSNR is obtained with only small memory and computation overhead.
Automatic video diagnosing method using embedded crypto-watermarks

This paper proposes a novel automatic video diagnosing method. The purpose of this study is to detect the attack added on the authorized video and identify the attack category. The video is added with the crypto-watermarks using dual-domain quaternary watermarking algorithm in advance. The crypto-watermarks, which are generated using visual cryptography, have different capabilities against the various attacks. We extract the watermarks from the suspected video, measure the bit-error-rate between the extracted and specified crypto-watermarks, and then analyze bit-error-rates to determine what kind of attack added on the video. The experimental results demonstrate that the proposed method not only can identify the single attack, but it can identify the composite attack and detect the corrupted frames. Even if the video is not embedded with crypto-watermarks, we can differentiate it from the authorized videos.
Design of IIR allpass fractional-delay fractional Hilbert transformer using complex cepstrum

The IIR allpass fractional-delay fractional Hilbert transformer is designed in the complex-cepstrum domain. The maximal flatness criterion on the phase response is considered for the midband frequency. Two independent systems of linear equations are formulated, resulting in closed-form solutions of the even-index and odd-index parts of complex cepstrum of the denominator polynomial. Moreover, they are proportional to the two design parameters: fractional delay and phase shift. This is attractive in that a tunable scheme for variable parameters is realizable. Only two normalized complex-cepstrum sequences need to be designed, stored and tuned by scaling. Both nonre-cursive and recursive algorithms are available for renewing the filter coefficients from the complex cepstrum.
Compressed Sensing Detector Design for Space Shift Keying in MIMO Systems

Space shift keying (SSK) modulation and its extension, the generalized SSK (GSSK), present an attractive framework for the emerging large-scale MIMO systems in reducing hardware costs. In SSK, the maximum likelihood (ML) detector incurs considerable computational complexities. We propose a compressed sensing based detector, NCS, by formulating the SSK-type detection criterion as a convex optimization problem. The proposed NCS requires only O(ntNrNt) complexity, outperforming the O(NrNtnt) complexity in the ML detector, at the cost of slight fidelity degradation. Simulations are conducted to substantiate the analytical derivation and the detection accuracy.
Fractionally spaced blind equalization using polyperiodic linear filtering

Performance of fractionally spaced equalizers using polyperiodic linear filtering is depicted. The fractionally sampled version of an arbitrary stable channel's outputs with stationary random inputs exhibit cyclostationarity with cycle frequencies being integer multiples of the reciprocal of the oversampling factor. By optimally polyperiodic linear filtering the oversampled outputs, we can fully utilize the cyclostationary property. With some traditional Bussgang techniques, such as stop-and-go decision-directed method, to adaptively update the filter coefficients, the convergence rate of the fractionally spaced equalizers proposed is improved, while the complexity retains in the same order as original Bussgang ones. Some computer simulation results are shown to demonstrate the improvement we can achieve.
Closed-form design of maximally flat FIR Hilbert transformers, differentiators, and fractional delayers by power series expansion

In this paper, novel closed-form designs of the FIR Hilbert transformers, maximally flat digital differentiators and fractional delayers are proposed. The transfer functions of these filters are analytically obtained by expanding some suitable functions into power series. Efficient implementations can be derived from the resultant transfer functions. The weighting coefficients and the building blocks of these filters are explicitly expressed in closed form. The proposed filter structures are more robust to the coefficient quantization than the direct form.
Cross-Terms Analysis in the Modified Instantaneous Power Spectrum

This correspondence examines cross terms in the modified version of the instantaneous power spectrum (MIPS), which is a smoothed form of the real part of the Rihaczek distribution. MIPS was reported recently to be less sensitive to the poor resolution of spectro- gram and the cross terms in the pseudo Wigner-Ville distribution (PWVD). However, in this correspondence we will show that like PWVD, the MIPS possesses cross terms too. The only differences be- tween them are the location and the oscillating frequency of the cross terms. We deduce that the cross terms of the MIPS are located in about the same region of the autoterms, while the cross terms of the WVD are located midway between the autoterms. The undesirable cross terms and artifact between different spectral components are much less se- vere and interfere less with each other in MIPS than in PWVD cases.  Page originally defined the instantaneous power specturm (IPS) as the derivative of the running energy spectrum (I), which satis- fied many of the properties of time-frequency distribution. How- ever, its ringing effect blocks its application. Hippenstiel and De Oliveira (2) advocated the use of the Fourier transform of an av- eraged correlation function estimate. This estimate is further mod- ified by applying a sliding window after forming the correlation estimate. The result, a smoothed version of the real part of the Rihaczek distribution (3), is a modified version of IPS. Hippenstiel shows that the MIPS can be less sensitive to the time-frequency resolution tradeoff problem occurring in the spectrogram 141 and the cross-term interference problem occurring in Wigner-Ville dis- tribution (WVD) (5)-(7). Moreover, the modified IPS (MIPS) can avoid the ringing effect which is a major problem in Page's IPS method. However, in this correspondence we will show that. like PWVD, the MIPS possesses cross terms too. Compared with WVD, the only differences between them are the location and the oscil- lating frequency of the cross terms. This correspondence will also show why the modified IPS reduces the ringing effect.
A new 3D unseen visible watermarking and its applications to multimedia

In this paper, a novel data hiding scheme, 3D unseen visible watermarking (UVW) based on depth no-synthesis-error (D-NOSE) model is proposed. The proposed method has the ability to detect which region of a depth map is suitable for watermark embedding and calculate optimal variation of pixel values for watermarking. The watermark is embedded into the suitable region by modifying the depth map with optimal variation pixel values to ensure that the watermarked cover can be perceived the same as the original one under normal rendering conditions. In the proposed 3D UVW scheme, hidden information can be extracted successfully by the human visual system (HVS) when changing the rendering conditions. Experimental results prove that the proposed scheme has the robustness and imperceptibility while depth distortions follow the thresholds derived from this paper.
Random Discrete Fractional Fourier Transform

In this letter, a new commuting matrix with random discrete Fourier transform (DFT) eigenvectors is first constructed. A random discrete fractional Fourier transform (RDFRFT) kernel matrix with random DFT eigenvectors and eigenvalues is then proposed. The RDFRFT has an important feature that the magnitude and phase of its transform output are both random. As an application example, a security-enhanced image encryption scheme based on the RDFRFT is illustrated.
2D Discrete cosine transform computation by fast polynomial transform algorithms

The 2D forward and inverse discrete cosine transforms (DCT) are mapped by polynomial transforms into several one-dimensional DFTs; This algorithm is more attractive for computing the "inverse" 2D DCT, it nicely eliminates N2premultiplications for the forward algorithm, and requires only N reduced real DFTs of size 2N; This inverse 2D DCT algorithm is 3 times faster than the forward one, more importantly it requires much less computation complexity than the most efficient recent algorithms.
Two-Dimensional Period Estimation by Ramanujan's Sum

Period estimation in one dimension (1-D) has been studied for years. However, 2-D period estimation is still a hard problem since it has three parameters to determine: length, width, and direction. Recently, a special kind of 2-D function called 2D-gcd-delta function is proposed. It has close relationship with Ramanujan's sum and the 2-D periodicity matrix. In this paper, we will describe how to use this function to decompose an image into subband signals. Each subband signal will have its own periodicity matrix so we also provide a simple algorithm to calculate the least common multiple (LCM) of those subband signal periodicity matrices. Concrete experiments are given to prove the robustness of the proposed 2-D period estimation method.
M-Channel Perfect Recovery of Coarsened Graphs and Graph Signals With Spectral Invariance and Topological Preservation

In this paper, an M-channel perfect reconstruction filter bank based on a coarsening algorithm is proposed. Compared with most of the designs of graph filter banks that do not consider the graph reconstruction, our proposed design can provide the perfect graph reconstruction as well as perfect graph signal reconstruction. In the analysis part, the proposed filter bank provides a coarse version of the input graph as well as coarsened graph signal spectral invariant to the input signal. In the synthesis part, the filter bank perfectly reconstructs the input graph as well as input signal from their coarse version. The spirit of the proposed design is to partition the spectral information of the input graph and input graph signal into every channel. The partition method is adjustable and can be nonuniform. Two intuitive schemes named sort-by-eigenvalue and sort-by-intensity for uniform partition are introduced. In the proposed design, the coarsening operators are obtained through an existing coarsening algorithm, while the recovery operators are defined by taking the conjugate transpose of the coarsening operators. Besides, we address the relation between the proposed design and a framework of sampling graph signals based on the discrete sampling theory. It is shown that the coarsening operator in the proposed design is actually a special case of the sampling operator in the framework based on the discrete sampling theory. Experimental results are presented to demonstrate the effectiveness of the proposed design of filter banks.
Analytic closed-form matrix for designing higher order digital differentiators using eigen-approach

The eigenfilter method has been proposed for designing higher order differentiators very effectively. The design method is based on the computation of an eigenvector of an appropriate real, symmetric, and positive-definite matrix. The elements of this matrix are usually evaluated by very time-consuming numerical integration. We present simple analytic closed-form formulas to compute these matrix-elements very efficiently. Hence, the eigenfilter approach for differentiators becomes much easier and more accurate than before and design time is reduced greatly for designing long filters.
Tracking moving objects in image sequences using 1-D trajectory filter

The three-dimensional (3-D) Fourier transform of the nonaccelerating object in an image sequence lies on a plane passing through the origin of the 3-D frequency domain. Instead of using a 3-D frequency planar filter, we propose a new filter design technique for object tracking using a one-dimensional trajectory filter-in the spatiotemporal domain. This filter can track a moving object with linear or nonlinear trajectory without prior knowledge of the target trajectory. Also, it is easy to design and has a very low computational complexity. More importantly, it can be implemented in real time.
Effective color correction via chromaticity adjustment and least square approximation

According to the observation that an image under the canonical light has a nearly neutral chromaticity distribution, an efficient three-step color correction approach is proposed: First, a preliminary color-corrected image is generated by linearly shifting the chromaticity distribution of an input image towards the neutral point. Then, a least square approximation formulation is presented to derive the illuminant color from the preliminary color-corrected image. Finally, based on the derived illuminant color and the Von Kries model, a refined color-corrected image can be obtained. From the experimental results on the widely-used SFU image dataset, the proposed approach could achieve comparable or even better performances against other well-known methods. In addition, several web images are examined to further demonstrate the effectiveness of our approach.
A new discrete fractional Fourier transform based on constrained eigendecomposition of DFT matrix by Lagrange multiplier method

This paper is concerned with the definition of the discrete fractional Fourier transform (DFRFT). First, an eigendecomposition of the discrete Fourier transform (DFT) matrix is derived by sampling the Hermite Gauss functions, which are eigenfunctions of the continuous Fourier transform and by performing a novel error-removal procedure. Then, the result of the eigendecomposition of the DFT matrix is used to define a new DFRFT. Finally, several numerical examples are illustrated to demonstrate that the proposed DFRFT is a better approximation to the continuous fractional Fourier transform than the conventional defined DFRFT.
Age estimation via fusion of multiple binary age grouping systems

In this paper, we propose a new divide-and-conquer based method, called fusion of multiple binary age-grouping-estimation systems, for human facial age estimation. Under a specific constraint, such as a given facial feature or classification/regression method, what is the better framework for age estimation? First we employ multiple binary-grouping systems for age group classification. Each face image will be classified into one of the two groups. Within the two groups, two models are trained to estimate ages for the faces classified into their groups, respectively. We also investigate the effect of different age grouping systems on the performance of age grouping accuracy and age estimation error. In the last stage, we propose a sequentially selection algorithm to fuse some of the binary-grouping systems to get a final age estimation result. Experiments on the MORPH2 database demonstrate our framework for age estimation can achieve satisfying results and outperform other state-of-the-art age estimation approaches.
Enhancement and license plate detection in nighttime scenes using LDR images fusion from a single input image

The incidence of traffic accidents during nighttime is higher than daytime; hence the clues from nighttime images are urgently needed. However, the light source from a camera works only for certain distance, resulting in the defect of underexposure. In this paper, we present a high dynamic range imaging method for vehicle images under a nighttime environment. The idea consists of three steps based on a single input image: (i) the license plate detection, (ii) generation of differently exposed images with license stroke thickening, and (iii) integrating them into a synthesized HDR image, in which the license plate regions and the backgrounds are better visualized. Therefore, the proposed method can be applied to mobile imaging devices to provide the HDR function. Experimental results show that the proposed approach effectively enhance contrast, especially for nighttime vehicle scenes, while still preserving image details, color, and information.
Empirical mode decomposition descriptor for plane closed curves

Empirical mode decomposition (EMD) developed by Huang et ] is a nonlinear data analysis method for nonstationary real-valued time series. It has been applied extensively in many research areas. Recently, several generalized EMD methods for complex-valued data analysis was proposed [2]  .Since a plane closed curve comprises many two-dimensional (2D) space data points, one can imagine that the boundary points of a plane closed curve as a complex data sequence in the complex plane, and make use of the newly developed complex EMD (CEMD) to do further analysis. We have found that we can use CEMD to achieve boundary points noise-reduction of plane closed curves and perform shift-invariant, scale-invariant and rotation-invariant pattern recognition.