• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.27-35
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• 2010

Accurately extracting skin color regions is very important in various areas such as face recognition and tracking, facial expression recognition, adult image identification, health-care, and so forth. In this paper, we evaluate the performances of several skin color detection algorithms in indoor environments by changing the distance between the camera and the object as well as the background colors of the object. The distance is from 60cm to 120cm and the background colors are white, black, orange, pink, and yellow, respectively. The algorithms that we use for the performance evaluation are Peer algorithm, NNYUV, NNHSV, LutYUV, and Kimset algorithm. The experimental results show that NNHSV, NNYUV and LutYUV algorithm are stable, but the other algorithms are somewhat sensitive to the changes of backgrounds. As a result, we expect that the comparative experimental results of this paper will be used very effectively when developing a new skin color extraction algorithm which are very robust to dynamic real environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1697-1702
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• 2017

This paper proposes a forward vehicle movement estimation algorithm for the image-based forward collision warning. The road region in the acquired image is designated as a region of interest (ROI) and a distance look up table (LUT) is made in advance. The distance LUT shows horizontal and vertical real distances from a reference pixel as a test vehicle position to any pixel as a position of a vehicle on the ROI. The proposed algorithm detects vehicles in the ROI, assigns labels to them, and saves their distance information using the distance LUT. And then the proposed algorithm estimates the vehicle movements such as approach distance, side-approaching and front-approaching velocities using distance changes between frames. In forward vehicle movement estimation test using road driving videos, the proposed algorithm makes the valid estimation of average 98.7%, 95.9%, 94.3% in the vehicle movements, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1231-1238
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• 2005

This paper presents a new fast encoding algorithm for image vector quantization that incorporates the partial distances of multiple features with a multidimensional look-up table (LUT). Although the methods which were proposed earlier use the multiple features, they handles the multiple features step by step in terms of searching order and calculating process. On the other hand, the proposed algorithm utilizes these features simultaneously with the LUT. This paper completely describes how to build the LUT with considering the boundary effect for feasible memory cost and how to terminate the current search by utilizing partial distances of the LUT Simulation results confirm the effectiveness of the proposed algorithm. When the codebook size is 256, the computational complexity of the proposed algorithm can be reduced by up to the $70\%$ of the operations required by the recently proposed alternatives such as the ordered Hadamard transform partial distance search (OHTPDS), the modified $L_2-norm$ pyramid ($M-L_2NP$), etc. With feasible preprocessing time and memory cost, the proposed algorithm reduces the computational complexity to below the $2.2\%$ of those required for the exhaustive full search (EFS) algorithm while preserving the same encoding quality as that of the EFS algorithm.

• Korean Journal of Remote Sensing
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• v.14 no.2
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• pp.149-164
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• 1998

The main object of this study was to prove the effectiveness of different merging methods by using the high resolution IRS(Indian Remote Sensing Satellite)-1C panchromatic data and the multispectral Landsat TM data. The five methods used to merging the information contents of each of the satellite data were the intensity-hue-saturation(IHS), principal component analysis(PCA), high pass filter(HPF), ratio enhancement method and look-up-table(LUT) procedures. Two measures are used to evaluate the merging method. These measures include visual inspection and comparisons of the mean, standard deviation and root mean square error between merged image and original image data values of each band. The ratio enhancement method was well preserved the spectral characteristics of the data. From visual inspection, PCA method provide the best result, HPF next, ratio enhancement, IHS and LUT method the worst for the preservation of spatial resolution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1868-1873
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• 2021

This paper proposes the Hough transform(HT) using an extended lookup table(LUT) to reduce the computational burden of the HT that is a typical straight line detection algorithm, and analyzes its performance. The conventional HT also uses a LUT to the calculation of the parameter 𝜌 of all straight lines passing through an edge pixel of interest(ePel) in order to reduce the computational burden. However, the proposed HT adopts an extended LUT that can be applied to straight lines across the ePel as well as its peripheral edge pixels to induce more computational reduction. This paper proves the validity of the proposed algorithm mathematically and also verifies it through simulation. The simulation results show that the proposed HT reduces the multiplication computation from 49.6% up to 16.1%, depending on the image and the applied extended LUT, compared to the conventional HT.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.6
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• pp.335-344
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• 2014

As a kind of 2D spatial coordinate transform, image warping is a basic image processing technique utilized in various applications. Though image warping algorithm is composed of relatively simple operations such as memory accesses and computations of weighted average, real-time implementations on embedded vision systems suffer from limited computational power because the simple operations are iterated as many times as the number of pixels. This paper presents a real-time implementation of a look-up table(LUT)-based image warping using an FPGA. In order to ensure sufficient data transfer rate from memories storing mapping LUT and image data, appropriate memory devices are selected by analyzing memory access patterns in an LUT-based image warping using backward mapping. In addition, hardware structure of a parallel and pipelined architecture is proposed for fast computation of bilinear interpolation using fixed-point operations. Accuracy of the implemented hardware is verified using a synthesized test image, and an application to real-time lens distortion correction is exemplified.

• Journal of electromagnetic engineering and science
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• v.9 no.3
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• pp.152-158
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• 2009

We have developed a novel digital feedback predistortion(DFBPD) linearization based on RF feedback PD for the wide bandwidth modulated signals. The wideband PD operation is carried out by combining the DFBPD and memory lookup table(LUT). To experimentally demonstrate the linearization performance of the proposed PD technique for wideband signal, a class-AB amplifier using an LDMOSFET MRF6S23140 with 140-W peak envelope power is employed at 2.345 GHz. For a forward-link 2FA wideband code-division multiple-access signal with 10 MHz carrier spacing, the proposed DFBPD with memory LUT delivers the adjacent channel leakage ratio at an 10 MHz offset of -56.8 dBc, while those of the amplifier with and without DFBPD are -43.2 dBc and -41.9 dBc, respectively, at an average output power of 40 dBm. The experimental result shows that the new DFBPD with memory LUT provides a good linearization performance for the signal with wide bandwidth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1042-1047
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• 1999

In this paper, two kinds of digital predistorters are proposed and their performances are analyzed in order to minimize ACI and SNR degradation caused by nonlinearly amplified TC-16QAM signal and to transmit high speed data in power and bandwidth limited land mobile satellite channel. Our simulation results show that LUT predistorter reduces the out-of-band ACI more efficiently as compared to intersymbol interpolated predistorter. Regarding the reduction of in-band SNR and total power intersymbol interpolated predistorter outperforms LUT predistorter. In the simulation mobile satellite channel and nonlinear HPA are modeled by Rician channel and Fujitsu SSPA, respectively.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.109-114
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• 2005

Twofish cryptographic algorithm is concise algorithm itself than Rijndael cryptographic algorithm as AES, and easy of implementation is good, but the processing speed has slow shortcoming. Therefore this paper designed improved MDS block to improve Twofish cryptographic algorithm's speed. Problem of speed decline by a bottle-neck Phenomenon of the Processing speed existed as block that existing MDS block occupies Twofish cryptosystem's critical path. To reduce multiplication that is used by operator in MDS block this Paper removed a bottle-neck phenomenon and low-speed about MDS itself using LUT operation and modulo-2 operation. Twofish cryptosystem including modified MDS block designed by these result confirmed that bring elevation of the processing speed about 10$\%$ than existing Twofish cryptosystem.

• Journal of Communications and Networks
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• v.12 no.6
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• pp.544-557
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• 2010

This paper addresses the problem of controlling the envelope's power peak of single carrier modulated signals, band limited by root-raised cosine (RRC) pulse shaping filters, in order to reduce power amplifier back-off for very small aperture terminals ground stations. Magnitude modulation (MM) is presented as a very efficient solution to the peak-to-average power ratio problem. This paper gives a detailed description of the MM concept and its recent evolutions. It starts by extending the look-up-table (LUT) based approach of the MM concept to M-ary constellations with M ${\leq}$ 16. The constellation and RRC symmetries are explored, allowing considerable reduction on LUT computation complexity and storage requirements. An effective multistage polyphase (MPMM) approach for the MM concept is then proposed. As opposed to traditional LUT-MM solutions, MM coefficients are computed in real-time by a low complexity multirate filter system. The back-off from high-power amplifier saturation is almost eliminated (reduction is greater than 95%) with just a 2-stage MPMM system even for very demanding roll-off cases (e.g., ${\alpha}$ = 0,1). Also, the MPMM is independent of modulation in use, allowing its easy application to constellations with M > 16.