• Journal of Korean Society for Geospatial Information Science
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• v.13 no.2 s.32
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• pp.39-43
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• 2005

In this study, we analyzed the accuracy of the conversion from DLT parameters to physical camera parameters and optimized the use of DLT model for non-metric cameras in photogrammetric tasks. Using the simulated data, we computed two sets of physical camera parameters from DLT parameters and Bundle adjustment for various cases. Comparing two results based on the RMSE values of check points, we optimized the arrangement of GCPs for DLT.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.567-574
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• 2006

This paper focuses on lossy medical image compression methods for medical images that operate on three-dimensional(3-D) irreversible integer wavelet transform. We offer an application of unbalanced tree structure algorithm to medical images, using a 3-D unbalanced wavelet decomposition and a 3-D unbalanced spatial dependence tree. The wavelet decomposition is accomplished with integer wavelet filters implemented with the lifting method. We have tested our encoder on volumetric medical images using different integer filters and 16 coding unit size. The coding unit sizes of 16 slices save considerable dynamic memory(RAM) and coding delay from full sequence coding units used in previous works. If we allow the formation of trees of different lengths, then we can accomodate more transaxial scales than three. Then the encoder and decoder can then keep track of the length of the tree in which each pixel resides through the sequence of decompositions. Results show that, even with these small coding units, our algorithm with I(5,3)filter performs as well and better in lossy coding than previous coding systems using 3-D integer unbalanced wavelet transforms on volumetric medical images.

• Annual Conference of KIPS
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• 2013.05a
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• pp.367-370
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• 2013

단일 영상에서 3차원 정보를 획득하기 위해 가장 많이 사용되는 단서로는 소실점이 있다. 본 논문에서는 소실점을 추정하기 위해서 허프변환을 사용하여, 단일 영상의 소실점 탐색 시 유효 직선간의 기울기 값 비교 및 근접도를 구하여 교점 생성에 필요 없는 정보를 제거함으로서 소실점 추정 정확도를 높인 보다 정확한 소실점 탐색 기법을 제안하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.30-40
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• 2014

As the Hadamard transform can be generalized into the Jacket transform, in this paper, we generalize the Haar transform into the Jacket-Haar transform. The entries of the Jacket-Haar transform are 0 and ${\pm}2^k$. Compared with the original Haar transform, the basis of the Jacket-Haar transform is general and more suitable for signal processing. As an application, we present the DCT-II(discrete cosine transform-II) based on $2{\times}2$ Hadamard matrix and HWT(Haar Wavelete transform) based on $2{\times}2$ Haar matrix, analysis the performances of them and estimate them via the Lenna image simulation.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.231-234
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• 2009

본 논문에서는 고속 동영상 방식의 스킵 블록 예측을 이용한 변환 과정 및 양자화 과정 생략 기법에 대해 제안한다. 정수여현 변환과 양자화 과정을 이용하여 생략 가능 블록을 예측하고, 이를 이용하여 압축 효율에 영향 없이 효과적으로 양자화 생략하는 방식에 대해 기술한다. 실험 결과를 통해 제안 방식을 이용한 예측된 블록이 부가적인 계산 없이 효과적으로 예측되어 생략되었음을 확인할 수 있었다.

• Broadcasting and Media Magazine
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• v.7 no.3
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• pp.44-53
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• 2002

본 논문은 현재 ITU-T와 ISO에 의해서 공동으로 표준화 작업이 진행되고 있는 H.26이 MPEG-4 Part 10표준의 변환(transform) 및 양자화(quantization) 과정에서 대해서 서술하는 것을 목적으로 하고 있다. H.26이 MPEG-4 Part 10 에서는 H.263, MPEG-4등과는 달리 H.26이 MPEG-4 Part 10 표준은 정수 변환(integer transform)을 채택함으로 인해서 구현시의 분해능(resolution)에 따라서 달라질 수 있는 오차(mismatch)를 근원적으로 제거한 것을 가장 큰 특징으로 들 수 있다. 또한 변환 과정을 16 비트 연산으로 가능하도록 설계한 것 또한 여타 표준과 구별 할 수 있는 특징이라 하겠다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.552-554
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• 2015

본 논문은 AVX2 (Advanced Vector eXtension 2) 명령어 집합을 이용하여 HEVC (High Efficiency Video Coding) 복호화기의 역-변환 모듈을 고속화하는 방법을 제안한다. AVX2 명령어 집합은 256 비트 레지스터를 사용하여 다수의 데이터를 한번의 명령을 통해 병렬적으로 연산할 수 있으며 반복적인 산술 연산 혹은 논리 연산 구조에서 효율적이다. 제안하는 방법은 AVX2 명령어 집합을 이용하여 $8{\times}8{\sim}32{\times}32$ 크기의 TU (Transform Unit) 단위로 수행되는 역-변환 연산을 행렬의 곱 형태로 연산하여 고속화하였다. 실험 결과 AVX2 명령어 집합을 이용한 역-변환 연산은 Chen 알고리즘에 비해 평균 51% 속도 향상을 보였으며 SSE (Streaming SIMD Extension) 명령어 집합을 이용한 연산에 비해 평균 20%의 속도 향상 결과를 얻을 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.10
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• pp.72-81
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• 2011

In this paper, we proposed and designed a novel floating point converter which supports single and double precisions of IEEE754 standard. The proposed convertor supports conversions between floating point number single/double precision and signed fixed point number(32bits/64bits) as well as conversions between signed integer(32bits/64bits) and floating point number single/double precision and conversions between floating point number single and double precisions. We defined a new internal format to convert various input types into one type so that overflow checking could be conducted easily according to range of output types. The internal format is similar to the extended format of floating point double precision defined in IEEE754 2008 standard. This standard specifies that minimum exponent bit-width of the extended format of floating point double precision is 15bits, but 11bits are enough to implement the proposed converting unit. Also, we optimized rounding stage of the convertor unit so that we could make it possible to operate rounding and represent correct negative numbers using an incrementer instead an adder. We designed single cycle data path and 5 cycles data path. After describing the HDL model for two data paths of the convertor, we synthesized them with TSMC 180nm technology library using Synopsys design compiler. Cell area of synthesis result occupies 12,886 gates(2 input NAND gate), and maximum operating frequency is 411MHz.

• Journal of the Korean earth science society
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• v.34 no.1
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• pp.69-80
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• 2013

Terrain data is one of important basic data in various areas of Earth science. Recently, finer DEM data is available, which necessary to develop a method that deals with such huge data efficiently. This study was conducted on the lossless compression of DEM data and efficient partial reconstruction of terrain information from compressed data. In this study, we compressed the wavelet coefficients of DEM, obtained from integer wavelet transform (IWT) by entropy encoding. CDF (Cohen-Daubechies-Feauveau) 3.5 wavelet showed the best compression ratio of about 45.4% and the optimum decomposition level was 3. Results also showed that a small region of terrain could be restored from the inverse wavelet transform with a part of the wavelet coefficients that are related to such region instead of whole reconstruction. We discussed the potential applications of the terrain data compression for precise gravity terrain correction.

• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.732-743
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• 2008

In H.264/AVC, 4$\times$4 block transform is used for intra and inter prediction instead of 8$\times$8 block transform. Using small block size coding, H.264/AVC obtains high temporal prediction efficiency, however, it has limitation in utilizing spatial redundancy. Motivated on these points, we propose a multi-dimensional transform which achieves both the accuracy of temporal prediction as well as effective use of spatial redundancy. From preliminary experiments, the proposed multi-dimensional transform achieves higher energy compaction than 2-D DCT used in H.264. We designed an integer-based transform and quantization coder for multi-dimensional coder. Moreover, several additional methods for multi-dimensional coder are proposed, which are cube forming, scan order, mode decision and updating parameters. The Context-based Adaptive Variable-Length Coding (CAVLC) used in H.264 was employed for the entropy coder. Simulation results show that the performance of the multi-dimensional codec appears similar to that of H.264 in lower bit rates although the rate-distortion curves of the multi-dimensional DCT measured by entropy and the number of non-zero coefficients show remarkably higher performance than those of H.264/AVC. This implies that more efficient entropy coder optimized to the statistics of multi-dimensional DCT coefficients and rate-distortion operation are needed to take full advantage of the multi-dimensional DCT. There remains many issues and future works about multi-dimensional coder to improve coding efficiency over H.264/AVC.