• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.351-355
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• 1999

The amount of data stored, processed and transmitted in the multi-media systems has been growing very fast, especially for the image data. For example, it takes 0.75Mbytes to store 512 12 pixels of 24-bit color image. A video signal with 30 frames per second will require 22.5Mbytes of storage space. To solve this problem, we need a good image compression technique. Recently, many researches on the image compression technique based on the wavelet transform are being pursued to overcome the problems of traditional JPEG. This paper describes the architecture and design of two-dimensional wavelet transform circuit. To keep the sire of the circuit small, we tried to minimize the internal storage space by using external SDRAM. This circuit was designed in Verilog-HDL, synthesized using Design Compiler and verified using Verilog-XL.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.360-363
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• 1999

Video data compression is a major key technology in the field of multimedia applications. Variable-length coding is the most popular data compression technique which has been used in many data compression standards, such as JPEG, MPEG and image data compression standards, etc. In this paper, we present memory efficient VLC decoder architecture for MPEG-2 application which can achieve small memory space and higher throughput. To reduce the memory size, we propose a new grouping, remainder generation method and merged lookup table (LUT) for variable length decoders (VLD's). In the MPEG-2, the discrete cosine transform (DCT) coefficient table zero and one are mapped onto one memory whose space requirement has been minimized by using efficient memory mapping strategy The proposed memory size is only 256 words in spite of mapping two DCT coefficient tables.

• Proceedings of the IEEK Conference
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• 2000.11c
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• pp.89-92
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• 2000

The wireless network has bursty and high error rates. Due to the quite limited bandwidth in wireless networks, images are usually transmitted as a compressed version with VLC(variable length coding). Loss of coded data can affect a decoded image to a large extent, making concealment of errors caused by data loss an important issue. This paper presents a error concealment technique for DCT(Discrete Cosine Transform) based image coding. First, a method to estimate the missing DC coefficients of a JPEG coded image which is required for decoding the compressed image, is suggested and evaluated. Second, the missing data is interpolated by exploiting the probability of being nonzero and the correlation between adjacent blocks. In addition, since the these technique is computational efficient, it conserves system resources and power consumption, which are restrictive in mobile computers.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.3
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• pp.57-65
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• 1995

This paper presents a new classified vector quantization (VQ) technique using a neural network model in the transform domain. Prior to designing a codebook, the proposed approach extracts class features from a set of images using self-organizing feature map (SOFM) that has the pattern recognition characteristics and the same as VQ objective. Since we extract the class features from the training images unlike previous approaches, the reconstructed image quality is improved. Moreover, exploiting the adaptivity of the neural network model makes our approach be easily applied to designing a new vector quantizer when the processed image characteristics are changed. After the generalized BFOS algorithm allocates the given bits to each class, codebooks of each class are also generated using SOFM for the maximal reconstructed image quality. In experimental results using monochromatic images, we obtained a good visual quality in the reconstructed image. Also, PSNR is comparable to that of other classified VQ technique and is higher than that of JPEG baseline system.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1731-1734
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• 2003

In this paper, we describe an approach for image denoising using the lifting construction, with the spatial adaptive wavelet transform. The adaptive lifting scheme is implemented in spatial domain to be adjusted thresholds to reduce noise. In this approach we represent adaptive characteristics of biorthogonal wavelets for choosing predictors effectively. Predict filter is changed from sample to sample according to local signal features with their vanishing moments. We in this approach have implemented and applied to image denoising by finding a relevant minimax threshold. Experimental results show that the adaptive method of denoising process is compared with existing ones, such as non-adaptive wavelet, CRF(13, 7) and SWE(13, 7) wavelets used by JPEG2000.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1811-1814
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• 2003

In this paper, a novel watermarking technique is proposed to authenticate the owner-ship of copyright for the digital contents. Using the 2-level DWT(Discrete Wavelet Transform) we divide a specific frequency band into detailed blocks and apply PIM(picture information measure). After the complexity is calculated, the watermark is embedded in only on high complexity areas. Conventional watermarking technique damages to the original image, because it does not consider the feature of the whole area or a specific frequency band. Easily affected by noise and compression, it is difficult to extract the watermark. However, the proposed watermarking technique, considering the complexity of input image, does not damage to the original image Simulation result show that the proposed technique has the robustness of JPEG compression, noise and filtering such as a general signal processing

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1815-1818
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• 2003

Digital watermarking is technique, which owner's information is inserted in digital image, with intention to protecting a copyright of digital image. In watermarking for copyright and authentication, watermark shouldn't be distorted or disappeared after general image processes like a compression and filtering. In this paper, we present a new digital image watermarking algorithm which combines the discrete wavelet transform (DWT) and the singular value decomposition (SVD). Simulation results show that the newly proposed algorithm is not only robust nevertheless variable attacks like noise, filtering and JPEG compression but also secure in application.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1847-1850
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• 2003

In many image-coding applications such as web browsing, image databases, and telemedicine, it is needed that only a region of interest(ROI) is transmitted and then reconstructed first before the whole image is transmitted and reconstructed. The Maxshift method has been used as a standard one in this research about ROI coding in JPEG2000. However Maxshift method can process only one ROI, this paper suggests an improved Maxshift method which can process Multiple ROI haying the priority order. In this method, the ROI coefficient which has the high priority order can be moved to upward two bit plane in order to process multiple ROI.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.11
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• pp.152-161
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• 1996

This paper descrisbes the implementation of a 20D DCT that can be used for video conference, JPEG, and MPEG-related applications. The implemented DCT consists of two 1-D DCTs and a transposed memory between them, and uses ROM-based multipliers instead of conventional ones. As the system bit length, the minimum bit length that satisfies the accuracy specified by the ITU standard H.261 was chosen through the simulations using the C language. The proposed design uses a dual port RAM for the transposed memory, and processes two bits of input-pixel data simultaneously t ospeed up addition process using two sets of ROMs. The basic system architecture was designed using th Synopsys schematic editor, and internal modules were described in VHDL and synthesized to logic level after simulation. Then, the compass silicon compiler was used to create the final lyout with 0.8um CMOS libraries, using the standard cell approach. The final layout contains about 110, 000 transistors and has a die area of 4.68mm * 4.96mm, and the system has the processing speed of about 50M pixels/sec.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.144-146
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• 2006

The Data Matrix of two-dimensional bar codes is a new technology capable of holding relatively large amounts of data compared to the conventional one-dimensional bar code which is just a key that can access detailed information to the host computer database. A secret key is used to prevent a watermark from malicious attacks. We encoded copyright information into a Data Matrix bar code for encoding process and it was spread a pseudo random pattern using owner key. We embedded a randomized watermark into the image using watermark's embedding position, pattern generated with a secret key. The experimental results have shown that the proposed scheme has good quality and is very robust to various attacks, such as JPEG compression and noise. Also the performance of the proposed scheme is verified by comparing the copyright information with the information which is extracted from a bar code scantier.