• The Transactions of the Korea Information Processing Society
• /
• v.7 no.4
• /
• pp.1305-1315
• /
• 2000

It is known that a digital image enlargement technique can increase the size of he image but the practical enhancement of resolution is trifle because the frequency bandwidth of the original image is basically limited. To solve this problem, this paper proposes the digital image enlargement technique which interpolates the interpolation points of horizontal and vertical direction by weighting according to the direction of edge information with the component of FOI(First Order Interpolation)and output of the pseudomedian filter for image enlargement and interpolates the interpolation points of diagonal direction by selectively transposing the direction of the subwindows of the pseudomedian filter according to the distribution of neighbored pixels thereto in the extended image. According to the proposed methods, the digital image enlargement which preserves the characteristic of the pseudomedian filter capable of keeping the reconstruction of edge information and reflects the advantage of FOI can be performed. Therefore, visual artifacts could be effectively suppressed, and most characteristics and shape of the original image can be reconstructed as well.

• Journal of computational fluids engineering
• /
• v.11 no.4 s.35
• /
• pp.39-47
• /
• 2006

In this paper, the authors developed a multidimensional interpolation method inside a finite volume cell in the computation of high-order accurate numerical flux such as the fifth order WEND (weighted essentially non-oscillatory) scheme. This numerical method starts from a simple Taylor series expansion in a proper spatial order of accuracy, and the WEND filter is used for the reconstruction of sharp nonlinear waves like shocks in the compressible flow. Two kinds of interpolations are developed: one is for the cell-averaged values of conservative variables divided in one mother cell (Type 1), and the other is for the vertex values in the individual cells (Type 2). The result of the present study can be directly used to the cell refinement as well as the convective flux between finer and coarser cells in the Cartesian adaptive grid system (Type 1) and to the post-processing as well as the viscous flux in the Navier-Stokes equations on any types of structured and unstructured grids (Type 2).

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.39 no.1
• /
• pp.1-8
• /
• 2002

The color interpolation scheme can play an important role in overcoming the physical limitation of the CCD image sensor and in increasing the resolution of color signals, while most conventional approaches result in blurred edges and false color artifacts. In this paper, we have proposed an improved edge-adaptive color interpolation scheme for a progressive scan CCD image sensor with RGB color filter array The edge indicator function proposed utilizes not only the within-channel correlation but also the cross-channel correlation, and reflects the edge characteristics of an image adaptively. The color components unavailable for at each channel are interpolated along the edge direction, not across the edges, so that aliasing artifacts are supressed. Furthermore, we eliminated false color artifacts resulting from the color image formation model in the edge-adaptive color interpolation scheme by adopting the switching algorithm based on the color edge detection. Simulation results of the proposed algorithm indicate that the improved edge-adaptive color interpolation scheme produces quantitatively better and visually more pleasing results than conventional approaches.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.195-197
• /
• 2005

In the scalable extension of H.264/AVC, spatial scalability is provided residual information as encoding layered spatial resolution between layers. We use the inter-layer prediction to remove this redundancy. In the inter-layer prediction, as the prediction we can use the signal that is the upsampled signal of the lower resolution layer. In this case, coding efficiency can be different from optimal prediction by kinds of interpolation filter. This paper indicates technique to choose the interpolation filter and to enhance coding efficiency for finding more correct prediction in intra macroblock.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.189-191
• /
• 2005

In the scalable extension of H.264/AVC, the codec is based on a layered approach to enable spatial scalability. In each layer, the basic concepts of motion compensated prediction and intra prediction are employed as in standard H.264/AVC. Additionally inter-layer prediction algorithm between successive spatial layers is applied to remove redundancy. In the inter-layer prediction, as the prediction we can use the signal that is the upsampled signal of the lower resolution layer. In this case, coding efficiency can be variable as the kinds of interpolation filter. In this paper, we investigate the approach to select the interpolation filter for residual signal in order to optimal prediction.

• The Journal of the Acoustical Society of Korea
• /
• v.20 no.1
• /
• pp.13-20
• /
• 2001

Adaptive digital filters with long impulse response such as acoustic echo canceller and active noise controller suffer from slow convergence and computational burden. Subband techniques and multirate signal processing have been recently developed to improve the problem of computational complexity and slow convergence in conventional adaptive filter. Any FIR transfer function can be realized as a serial connection of interpolators followed by subfilters with a sparse impulse response. In this case, each interpolator which is related to the column vector of Hadamard matrix has band-pass magnitude response characteristics shifted uniformly. Subband technique using Hadamard transform and decimation of subband signal to reduce sampling rate are adapted to system modeling and acoustic noise cancellation In this paper, delayless subband structure with nonuniform bandwidth has been proposed to improve the performance of the convergence speed without aliasing due to decimation, where input signal is split into subband one using tree-structured filter bank, and the subband signal is decimated by a decimator to reduce the sampling rate in each channel, then subfilter with sparse impulse response is transformed to full band adaptive filter coefficient using Hadamard transform. It is shown by computer simulations that the proposed method can be adapted to general adaptive filtering.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.20 no.4
• /
• pp.369-375
• /
• 2011

Design is important in the IT, digital appliance, and auto industries. Aesthetic and art images are being applied for better quality of the products. Most image patterns are complex and much lead-time is required to implement them to the product design process. A precise reverse engineering method generating 2.5D engraving models from 2D artistic images is proposed through the image processing, NURBS interpolation and 2.5D reconstruction methods. To generate 2.5D TechArt models from the art images, boundary points of the images are extracted by using the adaptive median filter and the novel MBF (modified boundary follower) algorithm. Accurate NURBS interpolation of the points generates TechArt CAD models. Performance of the developed system has been confirmed through the quick turnaround 2.5D engraving simulation linked with the commercial CAD/CAM system.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.52 no.10
• /
• pp.606-610
• /
• 2003

Noise subtraction using reference channel data has been used to improve signal-to-noise ratio in magnetoencephalography. In this paper, an adaptive noise subtraction model is proposed and parameters for the model are optimized. A criterion to determine an optimal update period for the filter coefficients is proposed based on the ratio of peak amplitude of evoked field (N100m) divided by the output standard deviation. Experiments are carried out using a 40 channel MEG system. From the experiments, the proposed noise subtraction method shows superior performances over existing non-adaptive methods. Two-dimensional topographic map is shown for a diagnosis with a cubic spline interpolation.

• Journal of Broadcast Engineering
• /
• v.18 no.1
• /
• pp.10-20
• /
• 2013

Nowadays, video technology has been successfully improved creating tremendous results. As video technology improve, multimedia devices and demands from users are diversified. Therefore, a video codec used in these devices should support various displays with different resolutions. The technology to generate a higher resolution image from the associated low-resolution image is called interpolation. Interpolation is generally performed in either the spatial domain or the DCT domain. To use the advantages of both domains, we have proposed the new adaptive interpolation algorithm based on edge direction, which adaptively exploits the advantages of both domains. The experimental results demonstrate that our algorithm performs well in terms of PSNR and reduces the blocking artifacts.

• 한국전산유체공학회:학술대회논문집
• /
• 2006.10a
• /
• pp.47-50
• /
• 2006

In the aeroacoustic application of computational fluid dynamics, the physical phenomena like the crackle in the unsteady compressible jets should be based on very time-accurate numerical solution. The accuracy of the present numerical scheme is extended to the fifth order, using the WENO filter to the sixth-order central difference computation. However, the computational capacity is very restricted by the environment of computational power, so therefore the quadrilateral adaptive grids technique is introduced for this high-order accuracy scheme. The first problem is the multi-dimensional interpolation between fine and coarse grids. Some general benchmark problems are solved to show the effectiveness of this method.