• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.23-33
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• 1996

This paper deals with the design of a recursively-indexed binary code for facsimile soruces and its performance. Sources used here are run-lengths of white pixels form higher-resolution facsimile. The modified huffman code used for G.3 facsimile is chosen for the performance comparison. Experiments confirm the fact that recursive indexing preserves the entropy of a memoryless geometric source: the entropy of recursively-indexed physical surce iwth roughly geometric distributin remains within 2% of the empirical source entropy. The designed recursively-indexed binary codes consist of a code applied to text-type documents and to graphics - type documents is compared iwth that of the modified huffman code. Numerical resutls show that the modified huffman code performs well for text-type documents and not equally well for graphics-tyep documents. On the other hand, recursively-indexed binary codes have shown a better performance for graphics-type documents whose distribution are similar to a geometric distribution. Specifically, the code rates of recursively-indexed binary codes with 60 codewords are from 8% to 20% of the empirical source entropy smaller than that of th emodified huffman code with 91 codewords.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.111-117
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• 2007

We present an efficient decoding scheme for Huffman codes in which we use a properties of canonical prefix tree. After Huffman tree is converted to canonical Huffman tree, we represent Huffman tree with minimum information using rules associated with values of nodes in canonical tree. The proposed scheme can reduce memory to store Huffman tree information while maintains the same Processing time. The memory size in order to represent tree information is 2h + 2klogn which is less than those of previous methods. But the number of search is similar to previously proposed techniques.

• Journal of IKEEE
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• v.22 no.3
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• pp.850-853
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• 2018

In this paper, we propose a decoding method using a balanced binary tree and a canonical Huffman tree for efficient decoding of Huffman codes. The balanced binary tree scheme reduces the number of searches by lowering the height of the tree and binary search. However, constructing a tree based on the value of the code instead of frequency of symbol is a drawback of the balanced binary tree. In order to overcome these drawbacks, a balanced binary tree is reconstructed according to the occurrence probability of symbols at each level of the tree and binary search is performed for each level. We minimize the number of searches using a canonical Huffman tree to find level of code to avoid searching sequentially from the top level to bottom level.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1411-1417
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• 2014

An MPEG-2 AAC Huffman decoding method based on the fixed length compacted codeword tables, where each codeword can contain multiple number of Huffman codes, was proposed. The proposed method enhances the searching efficiency by finding multiple symbols in a single search, i.e., a direct memory reading of the compacted codeword table. The memory usage is significantly saved by separately handling the Huffman codes that exceed the length of the compacted codewords. The trade-off relation between the computational complexity and the amount of memory usage was analytically derived to find the proper codeword length of the compacted codewords for the design of MPEG-2 AAC decoder. To validate the proposed algorithm, its performance was experimentally evaluated with an implemented MPEG-2 AAC decoder. The results showed that the computational complexity of the proposed method is reduced to 54% of that of the most up-to-date method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.1
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• pp.57-68
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• 2004

Although variable-length codes (VLCs) increase coding efficiency using the statistical characteristics of the source data, they have catastrophic effects from bit errors in noisy transmission environments. In order to overcome this problem with VLCs, reversible variable-length codes (RVLCS) have recently been proposed owing to their data recovering capability. RVLCS can be divided into two categories: symmetrical and asymmetrical RVLCs. Although the symmetrical RVLC has generally more overheads than the asymmetrical RVLC, it has some advantages of simpler design and more efficient memory usage. However, existing symmetrical RVLCs still have high complexity in their code design and some room for improvement in coding efficiency. In this paper, we propose a new algorithm for constructing a symmetrical RVLC from the optimal Huffman code table. The proposed algorithm has a simpler design process and also demonstrates improved performance in terms of the average codeword length relative to the existing symmetrical RVLC algorithms.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.137-140
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• 2003

In this paper, we propose a new construction algorithm for the reversible variable-length code (RVLC) using a simplified average length function of the optimal Huffman code. RVLC is introduced as one of the error resilience tools in H.263+ and MPEG-4 owing to its error-correcting capability. The proposed algorithm demonstrates an improved performance in terms of the average codeword length over the existing HVLC algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.11
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• pp.4443-4462
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• 2020

This paper proposes a new framework of reversible data hiding scheme for absolute moment truncation coding (AMBTC) compressed images. AMBTC-based RDH can be applied to optical remote sensing (ORS) image transmission, which achieves target region preservation and image compression simultaneously. Existing methods can be concluded as two types. In type I schemes, stego codes mimic the original AMBTC format where no file bloat occurs, yet the carried secret data is limited. Type II schemes utilize predication errors to recode quantity levels of AMBTC codes which achieves significant increase in embedding capacity. However, such recoding causes bloat inside stego format, which is not appropriate in mentioned ORS transmission. The proposed method is a novel type I RDH method which prevents bloat inside AMBTC stego codes with significant improvement in embedding capacity. The AMBTC compressed trios are grouped into two categories according to a given threshold. In smooth trio, the modified low quantity level is constructed by concatenating Huffman codes and secret bits. The reversible contrast mapping (RCM) is performed to complex trios for data embedment. Experiments show that the proposed scheme provides highest payload compared with existing type I methods. Meanwhile, no expansion inside stego codes is caused.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.439-446
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• 2011

In this paper, we proposed and implemented a dedicated hardware for Huffman coding which is a method of entropy coding to use compressing multimedia data with video coding. The proposed Huffman codec consists Huffman encoder and decoder. The Huffman encoder converts symbols to Huffman codes using look-up table. The Huffman code which has a variable length is packetized to a data format with 32 bits in data packeting block and then sequentially output in unit of a frame. The Huffman decoder converts serial bitstream to original symbols without buffering using FSM(finite state machine) which has a tree structure. The proposed hardware has a flexible operational property to program encoding and decoding hardware, so it can operate various Huffman coding. The implemented hardware was implemented in Cyclone III FPGA of Altera Inc., and it uses 3725 LUTs in the operational frequency of 365MHz

• Convergence Security Journal
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• v.7 no.2
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• pp.57-63
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• 2007

The security of data in network is provided by encryption. Selective encryption is a recent approach to reduce the computational cost and complexity for large file size data such as image and video. This paper describes techniques to encrypt Huffman code and discusses the performance of proposed scheme. We propose a simple encryption technique applicable to the Huffman code and study effectiveness of encryption against insecure channel. Our scheme combine encryption process and compression process, and it can reduce processing time for encryption and compression by combining two processes.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2615-2628
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• 1997

In this paper, a new codebook design algorithm is proposed. It uses a DCT map based on two-dimensional discrete cosine of transform (2D DCT) and finite state vector quantizer (FSVQ) when the vector quantizer is designed for image transmission. We make the map by dividing input image according to edge quantity, then by the map, the significant features of training image are extracted by using the 2D DCT. A master codebook of FSVQ is generated by partitioning the training set using binary tree based on tree-structure. The state codebook is constructed from the master codebook, and then the index of input image is searched at not master codebook but state codebook. And, because the coding of index is important part for high speed digital transmission, it converts fixed length codes to variable length codes in terms of entropy coding rule. The huffman coding assigns transmission codes to codes of codebook. This paper proposes single-side growing huffman tree to speed up huffman code generation process of huffman tree. Compared with the pairwise nearest neighbor (PNN) and classified VQ (CVQ) algorithm, about Einstein and Bridge image, the new algorithm shows better picture quality with 2.04 dB and 2.48 dB differences as to PNN, 1.75 dB and 0.99 dB differences as to CVQ respectively.