nils-herrmann/clean_scirepeval huggingface dataset:
Joint bilateral based image denoising using multi-sized 2D hard threshold

Non-local processing based denoising methods obtain high quality outputs. However, they have high calculation costs due to the non-local processing. In this paper, we focus on the bilateral filter instead of non-local processing. Although bilateral filter is a traditional local processing filter which can preserve edges, it cannot remove strong noise. Therefore, we utilize the joint bilateral filter, which calculates filter coefficients using another reference image. For adaptation to single image denoising, we utilize a pre- estimated image by the hard threshold operation in 2D frequency domain. To obtain a pre-estimated noiseless image while preserving image details, we apply multi-sized hard threshold operation and aggregate their outputs. Moreover, we change the estimation of the joint bilateral filter coefficients whether a target pixel is in an edge regions or not. By these improvements, our proposed method removes noise with preserving image details in a low calculation cost and experimental results show our method has comparable quality to non-local denoising methods.
Design of IIR digital filters in the complex domain by transforming the desired response

In this paper, we present a new design method of IIR digital filters with an equiripple magnitude response in the complex domain. This method is based on solving a least square solution iteratively. At each iteration, the desired response is transformed so as to have equiripple error. Hence the algorithm is very simple and does not need a special software. By this method, an equiripple solution is obtained very quickly with less computational complexity. Finally, we show some examples to validate the proposed method.
Colorization based on piecewise autoregressive model

Colorization is a technique to produce color components for grayscale images with color assigned information provided by the user. The conventional method colorizes via propagating the assignations with weights of neighborhood pixels. In this paper, we propose the colorization method based on the piecewise auto-regressive (AR) model. The proposed method calculates weights considering taking account of an image structure, and improves objective and perceptual qualities of colorized images compared with the conventional method.
A direction-adaptive image coding using two-dimensional direct lifting wavelet transform

In this paper, a novel direction-adaptive image coding scheme is introduced by using two-dimensional adaptive directional lifting-based wavelet transform (2D-ADLWT). Conventionally, one-dimensional ADLWT (1D-ADLWT) has been proposed. However, it requires large amount of computational cost for optimal lifting direction decision and image transformation. In this work, adaptive directional lifting is implemented by using 2D direct lifting wavelet transform and directional downsampling matrices. Direct 2D lifting structure can reduce the computational cost for image transformation and optimal lifting direction decision significantly. Moreover, in the simulation, it is shown that the proposed method is comparable to the 1D-ADLWT in terms of image coding efficiency. Thus, an effective ADLWT with low computational cost can be provided.
A new approach to the design of linear-phase biorthogonal filter banks and wavelets

In this research we propose a novel way to design biorthogonal filter banks and wavelets. Biorthogonal filter banks have more degrees of freedom than orthonormal ones. So, these have been well studied and some design methods reported. Almost all of these methods, however, require nonlinear programing. So we consider a simple design method which only requires one to solve linear equations iteratively. In our proposed method, we minimize the least square error of the perfect reconstruction (PR) condition so as to get around using the nonlinear programing technique. Finally we obtain the PR system.
Two-dimensional perfect reconstruction FIR filter banks with triangular supports

We present a theory and design of two-dimensional (2-D) perfect reconstruction (PR) filter banks (FBs) (PRFBs) in which the supports of the analysis and synthesis filters consist of two triangulars. The two-triangular FB can be realized by designing an appropriate 2-D complex prototype whose passband support is a triangle that is a half of a parallelepiped-shaped passband support defined by the sampling matrix. Then a complex prototype filter is modulated by the DFT, and each analysis filter is derived by taking the real part of the modulated output. We show that the two-triangular FB satisfies the condition of permissibility. A necessary and sufficient condition for 2-D PRFBs is derived. Moreover, we present a design method of the 2-D PRFB that minimizes the cost function consisting of the frequency constraint and PR condition. Finally, a design example is presented to confirm the validity of the proposed method.
Organization of optimal nonuniform lapped biorthogonal transforms based on coding efficiency

In this paper, we present optimal nonuniform lapped biorthogonal transforms for image compression. Subband coding using wavelet transforms have received a lot of attention because of multiresolution representation. The wavelet transform is regarded as a nonuniform filter bank and is constructed using the tree structure of a two-channel filter bank. However, it may not be optimal in the sense of energy compaction. If we can design nonuniform filter banks directly, it is possible to overcome the conventional wavelet transform. We then design a direct-structured nonuniform filter bank with a lapping window, called NULBT. Finally we show some examples and confirm the validity of our method.
Seam carving in wavelet transform domain

Content aware image resizing technique has become more important with the development of device technology. Although the seam carving method produces high-quality resized images, it requires high computational complexity. In this paper, we propose a faster content-aware image resizing technique. Our method performs seam carving in wavelet transform domain. This approach reduces the computational complexity of image resizing. To avoid breaking in the spatial continuity of an image, our method reduces the image width by scaling a seam width down instead of carving it out. In addition, the decomposition level can be decreased adaptively to avoid distortion. We show our method produces resized images with less distortion and less computational cost than the seam carving method.
A smooth extension for the nonexpansive orthogonal wavelet decomposition of finite length signals

In transform-based image coding, the periodic extension has the disadvantage that it might introduce high frequency components due to the artificial discontinuities at the signal boundaries. On the other hand, the symmetric extension cannot be applied to the two-channel orthogonal filter bank because linear phase is not possible. This paper describes a smooth extension method, which provides the symmetric decimated outputs of the analysis filters at the boundary, for the two-channel orthogonal filter bank to obtain nonexpansive subband signals. In our approach, the extended signal has the flexibility and we calculate the smooth one by singular value decomposition. Finally, several image coding and extended signal examples are shown to confirm the validity of the proposed approach.
Decorrelating compensation scheme for coefficient errors of a filter bank parallel A/D converter

In this letter, a parallel analog-digital (A/D) conversion scheme with a filter bank for low intermediate-frequency receivers is presented. The analysis filters of the filter bank divide the frequency components of the received signal, and achieve parallel A/D conversion. Therefore, the required conversion rates and the resolution of the A/D converters can be reduced and the receiver can demodulate wideband signals. As the analysis filters consist of analog components, their coefficients include errors. These errors cause mutual interference between signals in orthogonal frequencies. In order to remove this interference, a decorrelating compensation scheme is proposed.
Multiplierless lifting based FFT via fast Hartley transform

The multiplierless fast Fourier transform (FFT) with dyadic-valued (rational) coefficients is important for many signal processing tools. The proposed lifting based FFT (L-FFT) based on fast Hartley transform (FHT) has a simpler structure than existing ones because fewer lifting steps need to be approximated. In addition, it has a structure of real-valued calculation followed by complex-valued parts, thereby it requires fewer memories for the internal implementation than the conventional FFTs.
Quadrilateral Remeshing with Global Alignment

In this paper, we propose a new remeshing algorithm that captures the global structure of an object for 3D editing. The resulting meshes are quadrilateral, are of global alignment and have a multi-resolution structure. Additionally, their low-resolution mesh shows object features with a few vertices. Our algorithm is summarized as follows. First, a 3D object is converted into voxels, and then the object skeleton is computed. Next, the initial mesh is obtained from the skeleton. Finally, the remeshed object is yielded by moving vertices on the mesh to the voxel boundary. We show experimental results of remeshing some objects to validate the proposed algorithm.
A simplified lattice structure of two-dimensional generalized lapped orthogonal transform (2-D GenLOT) for image coding

In this paper, we propose a lattice structure of two-dimensional (2-D) linear-phase paraunitary filter banks (LPPUFBs) called as 2-D GenLOT. Muramatsu et al. have proposed a lattice structure of 2-D LPPUFBs conventionally. Our 2-D GenLOTs save design parameters and computational costs compared to the conventional 2-D LPPUFBs. We impose the regularity condition on the proposed FBs for image coding application. The 2-D GenLOTs perform an efficient image coding application.
Block-based seam carving

Content aware image resizing technique has become more important with the development of device technology. Although the seam carving method produces high-quality resized images, it requires high computational complexity. In this paper, we propose a block-based seam carving method, which is extended from the seam carving method. In our method, a seam element is a pixel block, and a seam is a path of blocks. The blocks on a seam are downsampled in the step of image shrinking. Our method creates resized images with less distortion and runs faster than seam carving. In addition, we present an image magnification technique with our method. Unlike the seam carving method, our technique defines the optimal seam for enlargement. Simulation results show the advantage of our method over seam carving method.
Demosaicing According to Edge Information Based on Frequency Band Partition

In this paper, we propose a new demosaicing method that interpolates RAW images in a Bayer pattern. We firstly apply a wavelet transform to a rotated G-channel of Bayer pattern. Then, according to the high frequency energy, Sobel operator and 2D FFT (Fast Fourier Transform) are performed parallelly as edge-classifiers. Missing samples are interpolated along the estimated edge direction. In both subjective and objective evaluations, the proposed demosaicing algorithm show better results than those of conventional methods.
Image resizing using improved seam merging

In this paper, we propose the improved seam merging method for content-aware image resizing. This method merges a two-pixel-width seam element into one new pixel in image reduction and inserts a new pixel between the two pixels in image enlargement. To preserve important contents and structure, our method uses importance and structure energies. Using the cartoon image of an original image for calculation of structure energy, our method can preserve main structure. In addition, we introduce new energy to suppress distortion generated by excessive reduction or enlargement in the iterative merging or inserting. Experimental results demonstrate that the proposed method can produce satisfactory results in both image reduction and enlargement.
Multiplierless fast algorithm for DCT via fast Hartley transform

Discrete cosine transform (DCT) is known as efficient frequency transform, and when it is implemented on software/hardware, multiplier is undesirable for faster implementation. This paper presents a realization of multiplierless fast DCT for lossy image/video coding on arbitrary devices. First, the proposed DCT is constructed by using fast Hartley transform (FHT). Next, the redundancy of the structure is eliminated by using several characteristics of rotation matrix. Then, multiplierless DCT is obtained by approximating rotation matrices to multiplierless lifting structures with adders and bit-shifters. Finally, the proposed DCT is validated by comparing with the conventional DCTs in image coding.
Generalized linear-phase paraunitary nonuniform filter bank (GenLPPUNUFB)

In this paper, we present the theory, design and imple-mentation of generalized linear-phase paraunitary nonuni-form filter bank (GenLPPUNUFB). Tree structure of wavelet transform is regarded as nonuniform filter bank (NUFB), and it will be adopted in JPEG2000 which will become the next standard for still image coding. However 2-channel linear-phase paraunitary NUFB (LPPUNUFB) does not exist except for Haar function, so it isn't optimal in the sense of transform coding gain. Although direct structured LPPUNUFB, which overcomes tree structured LPPUNUFB (Haar function), has already been presented , it is not general. Therefore we develop lattice structure of GenLPPUNUFB, and we show some examples and confirm the validity of our method.
2-dimensional recursive orthogonal wavelet transformation

The design of a 2-dimensional (2-D) recursive orthogonal wavelet based on iterated filter banks is investigated. To obtain the orthogonal wavelet, we use the parallel connection of some delays and a 2-D allpass filter. In this case, a pair of digital filters with orthogonality is obtained structurally and digital filters with arbitrarily orders can be designed. Furthermore a maximum number of zeros is put at aliasing frequencies in the lowpass filter to obtain the regularity of the wavelet. Design examples of discrete scaling and wavelet functions are presented.<<ETX>>
Dual-tree complex wavelet transform arising from cosine-sine modulated filter banks

The purpose of this paper is to show an another design approach of the M-band dual-tree complex wavelet transform (DTℂWT). Conventionally, M-channel cosine-sine modulated filter bank has been proposed as an extension of cosine modulated filter bank. It can be easily designed by the modulation of one prototype filter. In this paper, we show that it can be regarded as an alternative DTℂWT with respect to its relationship to the analyticity. In addition, we also present its shift-invariance, rich directional selectivity which are effective for the image processing. Therefore it can provide the simple design of M-band DTℂWT. In this paper, these properties are verified by theoretical analysis and demonstrations.
Reversible non-expansive symmetric convolution for M-channel lifting based linear-phase filter banks

This paper presents an effective signal boundary solution in lossy-to-lossless image coding which is the unification of lossy and lossless image coding. Although M-channel filter banks (FBs) for lossy image coding have several effective signal boundary solutions, M-channel lifting based FBs (L-FBs) for lossless image coding do not have such an effective signal boundary solutions due to rounding error in each lifting step. This paper proposes reversible non-expansive symmetric convolution for M-channel lifting based linear-phase FBs (L-LPFBs) to apply lossy-to-lossless image coding. Our proposal is validated by comparing with the periodic extension in lossy-to-lossless image coding.
Design and implementation of linear-phase 2-channel perfect reconstruction FIR filter banks with equiripple stopband

This paper presents a design and implementation method for linear phase 2-channel perfect reconstruction FIR filter banks with arbitrary filter length. In this method, which we call the weighted Lagrange-Newton method, by introducing the least squares weighting function into Horng's method (Lagrange-Newton method), QMF (Quadrature Mirror Filters) with good stopband attenuation can be designed. Furthermore, we show the construction of a 2-channel perfect QMF that achieves perfect reconstruction in spite of coefficient quantization.
Shape from Focus using Color Segmentation and Bilateral Filter

In this paper, we describe a new method for shape from focus using a set of the color segmentation and the bilateral filtering. The shape from focus estimates the geometrical shape of objects from the defocus level of images taken with different focal state. However, the conventional methods tend to fail in the shape estimation around the edge parts of objects and thin texture areas. To address the problems, we use the color segmentation in order to merge such areas by color, and then we interpolate the shape of lost part at each segment. The bilateral smoothing filter is used as the noise suppressor to improve the segmentation accuracy and also this bilateral filter is used to obtain the detail of textures, in other words, high frequency components of the focus measure. In addition, we also acquire the All-in-Focus image by this algorithm and the depth estimation is complemented by this image. By using this method, the lossless and noiseless shape of the object is obtained
The video coder with filterbank and subband motion estimation and compensation

We describe a new video coding scheme using filter bank and subband motion estimation and compensation. Inmost of video coding schemes such as MPEG , they have problem of blocking artifacts and computational complexity in motion estimation. We use Lapped Biorthogonal Transform (LBT) instead of DCT to reduce the blocking artifacts, and use the motion estimation in subband block domain to reduce the computational complexity. Intra-frames and the difference frames between the current and predicted frames in a video sequence are encoded by Efficient Embedded Zerotree Wavelet codec (EEZW) . They permit scalability, progressive transmission, and exact bit-rate control.
Design of IIR digital filters using all-pass networks

This paper presents a new method of designing the generalized IIR digital filter in the form of a parallel connection of two all-pass filters. It is shown that the numerator of the overall transfer function of this form can be expressed as real function of the all-pass coefficients. Then Remez algorithm is applied to the numerator and the rational approximation problem is transformed into a linear problem. IIR digital filters with the desired specification can be directly designed in the z-domain by this method. The proposed algorithm converges through a few iterations, and the amplitude property of IIR digital filter has equiripple.
Design of all-pass networks using Remez algorithm

A novel method for designing digital all-pass networks is introduced. Some design methods of all-pass networks have been proposed. However, the drawbacks of these schemes include the need for initial solutions and heavy computations. On the other hand, the design method proposed here finds the best uniform phase approximation through several iterations by solving linear equations. Phase error is regarded as the amplitude of complex error between the designed and desired all-pass function. Then, the Remez exchange algorithm is applied to the amplitude of the complex error, and it is approximated to equiripple. Maximum phase error is minimized, and the best uniform phase approximation in the Chebyshev sense is found. An optimal solution is obtained through several iterations without any initial guess of the solution.<<ETX>>
Design of linear phase paraunitary filter banks using an adaptive cascade lattice structure

M channel filter banks, which have perfect reconstruction and linear phase properties, have been studied extensively and several design methods have been addressed in the past. However, almost all of these methods require the nonlinear programming technique which contains some problems such as computational complexity, initial value and so on. In this paper, we propose a new design method of linear phase paraunitary filter banks. In our proposed method, we use an efficient least-mean-square-based adaptive algorithm to optimize the parameter, which minimizes the cost function, instead of using the nonlinear programming technique.
Blind source separation using correlation at neighboring frequencies

We propose blind source separation using correlation at neighboring frequencies based on DUET. DUET assume that sound sources meet the W-disjoint orthogonal and each source exists in the different position. Using these conditions, the amplitude and phase parameters are estimated to create amplitude-phase histogram from two mixtures. Each peak in the histogram corresponds to each source. However, because there exists acoustic echo in the real environment, the histogram distributes over wide range and we can not classify each source. In the frequency domain, acoustic signals have high correlations at neighboring frequencies. We incorporate this idea to the DUET to separate the sources more exactly. Through the simulation of both DUET and our new method, we compare the separation performance of our new method with that of DUET and confirm the validity of our method.
Smooth extension for nonexpansive wavelet decomposition of finite length signals

In transform-based image coding, the periodic extension has the disadvantage that it might introduce high frequency components due to the artificial discontinuities at the signal boundaries. On the other hand, the symmetric extension can't be applied to the two-channel orthogonal filter bank because linear phase is not possible. This paper describes a smooth extension method, which provides the symmetric decimated outputs of the analysis filters at the boundary, for the two-channel orthogonal filter bank to obtain nonexpansive subband signals. Then, extended signal has the flexibility under the nonexpansive condition. Therefore we can calculate the smooth extended signal by singular value decomposition. Finally, several image coding and extended signal examples are shown to confirm the validity of the proposed approach.
Design of IIR digital filters in the complex domain by transforming the desired response

In this paper, we present a new design method of infinite impulse response (IIR) digital filters with quasi-equiripple absolute error in the complex domain. This method is based on solving a least squares solution iteratively. At each iteration, the desired response for the least squares approximation is transformed to have equiripple error. This algorithm is efficient because there is no need for any initial value or complex optimization algorithm. By this method, a quasi-equiripple solution is obtained very quickly with less computational complexity. Moreover, by multiplying an arbitrary weighting function on the desired responses of passband and stopband, respectively, the error at the passband and stopband can be controlled. Finally, we show some examples to validate the proposed method.