Adaptive Tiling Research Articles

적응적 타일링 및 블록 매칭을 통한 포토 모자이크 알고리즘

모자이크란 여러 가지 빛깔의 재료를 조각조각 붙여서 무늬나 영상을 만드는 기법을 말하며, 최근에는 디지털 이미징 기술의 발달로 인하여 사진을 이용하여 영상을 만드는 포토 모자이크 기술들이 활용되고 있다. 본 논문에서는 적응적 타일링 및 블록 매칭을 통하여 포토 모자이크 영상을 만드는 컴퓨터 알고리즘을 제안한다. 제안한 알고리즘은 사진 데이터베이스의 생성 단계와 포토 모자이크 생성 단계로 구성된다. 사진 데이터베이스란 모자이크에 사용되는 사진(또는 타일)을 의미하며, 타일을 <TEX>$4{\times}4$</TEX>로 분할한 후에 각 영역의 RGB 평균값을 특징값으로 저장한다. 포토 모자이크 생성 단계는 입력 영상에 대하여 기 설정된 블록 크기로 분할한 후에 특징을 추출하는 과정, 인접한 블록들 사이의 유사도를 비교하여 병합하는 적응적 타일링 과정, 적응적 타일링을 통해 생성된 블록들을 사진 데이터베이스의 타일들과 유클리드 차이로 유사도를 비교하여 유사한 타일을 찾는 블록 매칭 과정 및 매칭된 타일의 명암값을 해당 블록의 명암값으로 교체하여 영상의 유사도를 높이는 밝기값 조정 과정으로 구성된다. 또한 인접 블록간 타일의 중복성을 최소화하는 기법을 적용하여 영상의 품질도 향상하였다. 제안한 알고리즘의 성능을 분석하기 위하여 안드레아 모자이크 소프트웨어와 비교하였고, 정량적인 분석 및 정성적인 분석에 있어서 제안한 알고리즘이 우수한 것으로 나타났다. Mosaic is to make a big image by gathering lots of small materials having various colors. With advance of digital imaging techniques, photomosaic techniques using photos are widely used. In this paper, we presents an automatic photomosaic algorithm based on adaptive tiling and block matching. The proposed algorithm is composed of two processes: photo database generation and photomosaic generation. Photo database is a set of photos (or tiles) used for mosaic, where a tile is divided into <TEX>$4{\times}4$</TEX> regions and the average RGB value of each region is the feature of the tile. Photomosaic generation is composed of 4 steps: feature extraction, adaptive tiling, block matching, and intensity adjustment. In feature extraction, the feature of each block is calculated after the image is splitted into the preset size of blocks. In adaptive tiling, the blocks having similar similarities are merged. Then, the blocks are compared with tiles in photo database by comparing euclidean distance as a similarity measure in block matching. Finally, in intensity adjustment, the intensity of the matched tile is replaced as that of the block to increase the similarity between the tile and the block. Also, a tile redundancy minimization scheme of adjacent blocks is applied to enhance the quality of mosaic photos. In comparison with Andrea mosaic software, the proposed algorithm outperforms in quantitative and qualitative analysis.

Large-Scale Physics-Based Terrain Editing Using Adaptive Tiles on the GPU

Physics-based approaches could simplify terrain modeling by increasing its realism. However, most simulations provide only a low level of user control because they fail on large-scale phenomena or focus only on the modeling of limited effects. A new physics-based system for digital terrain editing is suitable for digital-content authors such as game designers, artists, and 3D modelers. It doesn't assume in-depth knowledge about physics-based simulations. Users can load large terrains from external sources, generate them procedurally, or create them manually, and they can edit them at interactive frame rates on a GPU. To allow large-scale editing, the system divides terrain into tiles of different resolutions according to the terrain's complexity, and it stores each tile as a mip-map texture. In addition, the physics-based simulation uses different levels of detail, depending on the terrain-change dynamics. Compared to nonadaptive computation, this approach can achieve 50 percent speedup and use 25 percent less memory. The Web extra is a video that shows how physics-based approaches to modeling can process terrain sizes larger than what was previously possible.

A Low Complexity Noise Suppressor with Hybrid Filterbanks and Adaptive Time-Frequency Tiling

This paper proposes a low complexity noise suppressor with hybrid filterbanks and adaptive time-frequency tiling. An analysis hybrid filterbank provides efficient transformation by further decomposing low-frequency bins after a coarse transformation with a short frame size. A synthesis hybrid filterbank also reduces computational complexity in a similar fashion to the analysis hybrid filterbank. Adaptive time-frequency tiling reduces the number of spectral gain calculations. It adaptively generates tiling information in the time-frequency plane based on the signal characteristics. The average number of instructions on a typical DSP chip has been reduced by 30% to 7.5MIPS in case of mono signals sampled at 44.1kHz. A Subjective test result shows that the sound quality of the proposed method is comparable to that of the conventional one.

GIzMOs: Genuine Image Mosaics with Adaptive Tiling

Abstract We present a method that splits an input image into a set of tiles. Each tile is then replaced by another image from a large database such that, when viewed from a distance, the original image is reproduced as well as possible. While the general concept of image mosaics is not new, we consider our results as ‘genuine image mosaics’ (or short GIzMOs) in the sense that the images from the database are not modified in any way. This is different from previous work, where the image tiles are usually colour shifted or overlaid with the high‐frequency content of the input image. Besides the regular alignment of the tiles we propose a greedy approach for adaptive tiling where larger tiles are placed in homogenous image regions. By this we avoid the visual periodicity, which is induced by the equal spacing of the image tiles in the completely regular setting. Our overall system addresses also the cleaning of the image database by removing all unwanted images with no meaningful content. We apply differently sophisticated image descriptors to find the best matching image for each tile. For aesthetic and artistic reasons we classify each tile as ‘feature’ or ‘non‐feature’ and then apply a suitable image descriptor. In a user study we have verified that our descriptors lead to mosaics that are significantly better recognizable than just taking, e.g. average colour values.

Tile-based level of detail for the parallel age

Today's PCs incorporate multiple CPUs and GPUs and are easily arranged in clusters for high-performance, interactive graphics. We present an approach based on hierarchical, screen-space tiles to parallelizing rendering with level of detail. Adapttiles, render tiles, and machine tiles are associated with CPUs, GPUs, and PCs, respectively, to efficiently parallelize the workload with good resource utilization. Adaptive tile sizes provide load balancing while our level of detail system allows total and independent management of the load on CPUs and GPUs. We demonstrate our approach on parallel configurations consisting of both single PCs and a cluster of PCs

A new implementation of discrete bionic wavelet transform: Adaptive tiling

Bionic wavelet transform (BWT) is a biomodel-based adaptive time-frequency analysis technique. Due to its nonlinearity, it is difficult to realize the inverse BWT. To solve this problem, this paper introduces a new implementation for the discrete BWT (DBWT). The T-function from BWT is used to split the dyadic tiling map of DWT to obtain an adaptive DBWT tiling of the time-frequency plane. Quadrature-mirror filters, organized as the DBWT tiling map, are then employed to decompose the signal. This DBWT implementation makes the distortionless signal reconstruction possible. DBWT was used to decompose both simulated signal and actual nonstationary signals. Results show that DBWT performs better than discrete wavelet transform in demonstrating a more concentrated coefficient distribution in time-frequency plane. This proposed DBWT implementation will make BWT more applicable for the future nonstationary signal analysis.

The 6dF Galaxy Survey: samples, observational techniques and the first data release

The 6dF Galaxy Survey (6dFGS) aims to measure the redshifts of around 150 000 galaxies, and the peculiar velocities of a 15 000-member subsample, over almost the entire southern sky. When complete, it will be the largest redshift survey of the nearby Universe, reaching out to about z∼ 0.15, and more than an order of magnitude larger than any peculiar velocity survey to date. The targets are all galaxies brighter than Ktot= 12.75 in the 2MASS Extended Source Catalog (XSC), supplemented by 2MASS and SuperCOSMOS galaxies that complete the sample to limits of (H, J, rF, bJ) = (13.05, 13.75, 15.6, 16.75). Central to the survey is the Six-Degree Field (6dF) multifibre spectrograph, an instrument able to record 150 simultaneous spectra over the -field of the UK Schmidt Telescope. An adaptive tiling algorithm has been employed to ensure around 95 per cent fibring completeness over the 17 046 deg2 of the southern sky with | b | > 10°. Spectra are obtained in two observations using separate V and R gratings, that together give R∼ 1000 over at least 4000–7500 Å and signal-to-noise ratio ∼10 per pixel. Redshift measurements are obtained semi-automatically, and are assigned a quality value based on visual inspection. The 6dFGS data base is available at, with public data releases occurring after the completion of each third of the survey.

The tiling algorithm for the 6dF Galaxy Survey

The Six Degree Field Galaxy Survey (6dFGS) is a spectroscopic survey of the southern sky, which aims to provide positions and velocities of galaxies in the nearby Universe. We present here the adaptive tiling algorithm developed to place 6dFGS fields on the sky, and allocate targets to those fields. Optimal solutions to survey field placement are generally extremely difficult to find, especially in this era of large-scale galaxy surveys, as the space of available solutions is vast (2N dimensional) and false optimal solutions abound. The 6dFGS algorithm utilises the Metropolis (simulated annealing) method to overcome this problem. By design the algorithm gives uniform completeness independent of local density, so as to result in a highly complete and uniform observed sample. The adaptive tiling achieves a sampling rate of approximately 95%, a variation in the sampling uniformity of less than 5%, and an efficiency in terms of used fibres per field of greater than 90%. We have tested whether the tiling algorithm systematically biases the large-scale structure in the survey by studying the two-point correlation function of mock 6dF volumes. Our analysis shows that the constraints on fibre proximity with 6dF lead to under-estimating galaxy clustering on small scales (< 1 Mpc) by up to ~20%, but that the tiling introduces no significant sampling bias at larger scales.

Algorithm for achieving adaptive tiling of time axis for audio coding purposes

A new algorithm for achieving flexible tiling of the time axis for audio coding purposes is presented. It is based on the calculus of the distances among a predetermined number of time-frequency pairs. From the computed distances, a clustering process determines the final subdivision of each audio frame. Experimental results demonstrates the good performance of the proposed algorithm, which provides high coding efficiency with a reduced complexity.

The 2dF Galaxy Redshift Survey: spectra and redshifts

The 2dF Galaxy Redshift Survey (2dFGRS) is designed to measure redshifts for approximately 250 000 galaxies. This paper describes the survey design, the spectroscopic observations, the redshift measurements and the survey data base. The 2dFGRS uses the 2dF multifibre spectrograph on the Anglo-Australian Telescope, which is capable of observing 400 objects simultaneously over a 2° diameter field. The source catalogue for the survey is a revised and extended version of the APM galaxy catalogue, and the targets are galaxies with extinction-corrected magnitudes brighter than b J = 19.45. The main survey regions are two declination strips, one in the southern Galactic hemisphere spanning 80° × 15° around the SGP, and the other in the northern Galactic hemisphere spanning 75° × 10° along the celestial equator; in addition, there are 99 fields spread over the southern Galactic cap. The survey covers 2000 deg 2 and has a median depth of z = 0.11. Adaptive tiling is used to give a highly uniform sampling rate of 93 per cent over the whole survey region. Redshifts are measured from spectra covering 3600-8000 A at a two-pixel resolution of 9.0 A and a median S/N of 13 pixel - 1 . All redshift identifications are visually checked and assigned a quality parameter Q in the range 1-5; Q ≥ 3 redshifts are 98.4 per cent reliable and have an rms uncertainty of 85 km s - 1 . The overall redshift completeness for Q ≥ 3 redshifts is 91.8 per cent, but this varies with magnitude from 99 per cent for the brightest galaxies to 90 per cent for objects at the survey limit. The 2dFGRS data base is available on the World Wide Web at http://www. mso.anu.edu.au/2dFGRS.

An adaptive tiling of the time–frequency plane with application to multiresolution-based perceptive audio coding

The research efforts recently devoted to the theoretical treatment of time-varying filter bank structures have created an adequate environment for the development of adaptive analysis tools, useful in many signal processing problems. In this paper we present a complete adaptive analysis system suitable for the compression of audio signals; we would like to remark that our goal is not to develop a complete audio coder, just the appropriate analysis/synthesis scheme. For basis selection, we propose a search algorithm and a new cost function based on perceptual considerations. In addition, a procedure that determines the optimum length of the analysis segment is described. Examples are given of the performance of these algorithms on some representative audio signals. When the search method is compared with previous basis selection algorithms, we find and show that, for the application of audio compression, the perceptually driven basis selection algorithm leads to a much higher compression efficiency and better quality of the reconstructed signal.