• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2009년도 IWAIT
• /
• pp.498-503
• /
• 2009

As for Hadamard Transform, because the calculation time of this transform is slower than Discrete Cosine Transform (DCT) and Fast Fourier Transform (FFT), the effectiveness and the practicality are insufficient. Then, the computational complexity can be decreased by using the butterfly operation as well as FFT. We composed calculation time of FFT with that of Fast Complex Hadamard Transform by constructing the algorithm of Fast Complex Hadamard Transform. They are indirect conversions using program of complex number calculation, and immediate calculations. We compared calculation time of them with that of FFT. As a result, the reducing the calculation time of the Complex Hadamard Transform is achieved. As for the computational complexity and calculation time, the result that quadrinomial Fast Complex Hadamard Transform that don't use program of complex number calculation decrease more than FFT was obtained.

• 대한전자공학회논문지
• /
• 제24권2호
• /
• pp.301-308
• /
• 1987

In this paper, we have defined the Weighted Hadamard Transform (WHT) and developed efficient algorithms for the fast computation of the WHT. The WHT is applied to digital image processing and compared with Hadamard Transform (HT). We have weighted at the center spatial frequency domains of the Hadamard Transform and transmitted a image and then center high frequencies are neglected at the receiving. The WHT of signal to noise ratio(SNR) and image quality are enhanced than the HT.

• 한국통신학회논문지
• /
• 제11권4호
• /
• pp.251-258
• /
• 1986

TV와 같은 영상신호에는 중복도가 많이 존재하며, 이를 줄이기 위한 여러가지 방법들이 연구되고 있다. 본 논문에서는 Hadamard 변환을 이용하여 computer simulation과 실험 모델을 제작하여 데이터 압축에 관해 연구하였다. Hadamard matrix는 +1과 -1로 구성되며, row vector들은 서로 orthogonal하고 변환된 signal을 계산하기 위해서는 가산과 감산만이 필요하기 때문에 가산뿐 아니라 승산이 필요한 Fourier transform등 다른 orthogonal transform 에 비해 hardware구성이 용이하다. 링컨데이타 (64$ imes$64)를 8차와 16차 Hadamard 변환으로 simulation하였고, 8차를 hardware로 구성하였으며 이 경우 이론과 실험을 통해 연구한 결과 좋은 화질을 얻기 위해서는 2.0bits/sample가 필요했다.

• 전자공학회논문지
• /
• 제51권9호
• /
• pp.30-40
• /
• 2014

본 논문에서는 Hadamard 변환이 Jacket 변환으로 일반화 될 수 있는 것처럼 Haar 변환을 Jacket-Haar 변환으로 일반화 한다. Jacket-Haar 변환의 원소는 0 과 ${\pm}2^k$ 이다. original Haar 변환과 비교해서 Jacket-Haar 변환의 베이시스(basis)는 신호처리에 보다 적합하다. 응용으로 $2{\times}2$ Hadamard 행렬을 기반으로 한 DCT-II(discrete cosine transform-II)와 $2{\times}2$ Haar 행렬을 기반으로 한 HWT(Haar Wavelete transform)를 제시하고 이들의 성능을 분석하며 Lenna 이미지의 시뮬레이션을 통해 성능을 평가하였다.

• 대한전자공학회논문지
• /
• 제26권10호
• /
• pp.1617-1623
• /
• 1989

The introduction of the fast Fourier transform(FFT),an efficient computational algorithm for the discrete Fourier transform(DFT) by Cooley and Tukey(1965), has brought to the limelight various other discrete transforms. Some of the analog functions from which these transforms have been derived date back to the early 1920's, for example, Walsh functions (Walsh, 1923) and Hadamard Transform(Enomoto et al, 1965). Fast algorithms developed for the forward transform are equally applicable, exept for minor changes, to the inverse transform. In this paper, we present a simple pipelined Hadamard matrix(HM) which is used to develop a fast algorithm for the Hadamard Processor (HP). The Fast Hadamard Transform(FHT) can be derived using matrix partitioning techniques. The HP system is incorporated through a modular design which permits tailoring to meet a wide range of video data link applications. Emphasis has been placed on a low cost, a low power design suitable for airbone system and video codec.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
• /
• pp.1125-1128
• /
• 1993

We propose the new method about the neural-based pattern recognition by using Hadamard transform for the improvement of learning speed, stability and flexibility of network. We can obtain the spatial feature of pattern by Hadamard transformed pattern. We carried out an experiment to estimate the effect of Hadamard transform. We tried the learning of numeric patterns, and tried the pattern recognition with noisy pattern. As a result, the learning times of the network for the 'Hadamard' case is smaller than that of usual case. And the recognition rate of the network for the 'Hadamard' case is higher than that of usual case, too.

• 대한전기학회논문지:전력기술부문A
• /
• 제48권5호
• /
• pp.571-579
• /
• 1999

In this paper, a Hadamard transform imaging spectrometer(HTIS) is proposed by using a grill spectrometer. And we reconfigure the system by using the grill sectrometer which uses a left cyclic S-matrix instead of the conventional right cyclic one. Then, we model the Hadamard transform imaging spectrometer and apply the mask characteristics compensation method, i.e. $ {T}^{-1}$ method, to complete fast algorithm. Also, through computer simulations the superiority of the proposed system in this paper to the conventional Hadamard transform spectrometer(HTS) is proved and the performance of the two systems are compared by introducing average mean square error(AMSE) as the algebraic criterion.

• 대한전자공학회논문지TC
• /
• 제44권1호
• /
• pp.132-137
• /
• 2007

재킷 변환은 단순한 계산과 용이한 역변환, 그리고 크기 유연성을 갖는 변환의 일종이다. 재킷 변환은 잘 알려진 월쉬-아다마르 변환(WHT)과 중앙 하중 아다마르 변환(CWHT)의 일반화로서 이전 연구에서 보고한 바 있다. 본 논문에서는 WHT 또는 CWHT에서 유도되지 않는 새로운 부류의 재킷 변환을 제시한다. 이러한 부류의 변환은 임의의 우수 길이를 갖는 벡터에 대해 적용할 수 있고, 유한체에 대해 응용할 수 있으며, 오류 정정 부호의 구성에서도 유용하다.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제55권5호
• /
• pp.205-215
• /
• 2006

In this paper an optical power meter using Hadamard transform, which can be used in multiple channel optical elements alignment system, is proposed. A traditional optical power meter in multiple channel optical elements alignment system is able to judge how well the elements are aligned each other by measuring optical power of the first and the last two channels with at least two detectors. It has critical drawback that the alignment accuracy per channel is dependent on the number of detectors. The proposed optical power meter can get noise reduction by the Hadamard transform based multiplexing technique. The Hadamard transform based multiplexing technique using spatial light modulators is distinguished by the best enhancement of signal-to-noise ratio (SNR) for the reconstructed signals. Moreover, the noise reduction increases with increasing the order of multiplexing, namely the number of optical element channels. The proposed system is implemented by PDLC (Polymer Dispersed Liquid Crystal) mask which is operated by electric filed and generates optimal multiplexing patterns based on the Hadamard transform and single detector. It means that we obtain not only the each channel's optical power of multiple channel elements at once but also the best enhancement of SNR with single detector. Experimental results show that the proposed optical power meter is suitable for an active optical alignment system for multiple channel optical elements.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 하계학술대회 논문집 B
• /
• pp.616-619
• /
• 1997

The spectrum-recovery scheme in Hadamard transform spectroscopy is commonly implemented with a fast Hadamard transform (FHT). When the Hadamard or simplex matrix corresponding to the mask does not have the same ordering as the Hadamard matrix corresponding to the FHT, a modification is required. When the two Hadamard matrices are in the same equivalence class, this modification can be implemented as a permutation scheme. This paper investigates permutation schemes for this application. This paper is to relieve the confusion about the applicability of existing techniques, reveals a new, more efficient method: and leads to an extension that allows a permutation scheme to be applied to any Hadamard or simplex matrix in the appropriate equivalence class.