On the basis of the characteristics of cyclic codes, the codeword space can be partitioned into small subspaces where cyclically shifted codewords of a particular codeword occupy the same subspace. A cyclically permutable code generates codewords belonging to each subspace. However, no approach for the efficient construction of cyclically permutable code from binary cyclic codes has been proposed thus far. In this study, we propose an approach for the efficient and systematic construction of a cyclically permutable code from a cyclic code by utilizing an algebraic property. The proposed coding method improves the robustness of watermarking, particularly for video frames, against a clipping attack

Homomorphic property of public-key cryptosystems is applied for several cryptographic protocols, such as electronic cash, voting system, bidding protocols, etc. Several fingerprinting protocols also exploit the property to achieve an asymmetric system. However, their enciphering rate is extremely low and the implementation of watermarking technique is difficult. In this paper, we propose a new fingerprinting protocol applying additive homomorphic property of Okamoto-Uchiyama encryption scheme. Exploiting the property ingenuously, the enciphering rate of our fingerprinting scheme can be close to the corresponding cryptosystem. We study the problem of implementation of watermarking technique and propose a successful method to embed an encrypted information without knowing the plain value. The security can also be protected for both a buyer and a merchant in our scheme.

The data structure of Huffman codes and its application to efficient encoding and decoding of Huffman codes are studied in detail. The tree structure is presented by a two-dimensional array which can be applied for the decoding of Huffman codes as a state transition table of the finite-state decoding automaton. Inversion produces a one-dimensional state transition table of the semiautonomous finite-state sequential machine which can be used as a Huffman encoder with a push-down stack. The encoding and decoding procedures are simple and efficient. It is not only possible to implement by simple hardware but is also applicable to software implementation.

A new simple algorithm for unique ranking ofq-ary sequences is presented, using a general triangle (a triangular array of integers) that includes the well-known Pascal triangle as a special case. Applying the algorithm gives a new multilevel source coding scheme for which the prefix is the Lee weight and the suffix is the ranking number. A detailed analysis of the asymptotic performance shows that the new scheme is weighted universal. The inverse enumeration algorithm for decoding is also presented, and the complexity of the algorithm increases linearly in proportion to the length of source sequences.

The performance of several simple noiseless coding schemes for binary finite-order Markov sources is considered. Bounds are derived on the maximum difference between the performance achievable by the schemes and the entropy of the sources. The schemes can be modified for the case where the source statistics are unknown.

Correlation decoding is an optimal scheme of soft-decision decoding for error-correcting codes in the sense of minimum block-error probability. However, it is very difficult to apply the scheme when the number of information digits is large because of decoding complexity. A new algorithm for soft-decision decoding is presented, simplifying the correlation scheme by selecting certain codewords and decreasing decoding complexity by using erasure information. Any desired block-error probability between the error Probabilities of correlation and hard-decision decoding can be realized by setting up a suitable threshold value 0 for erasure decision. Computer simulation has been performed for Golay(23,12,7)code and BCH(15,7,5)code.

In this paper a new recognition system of distorted patterns is presented, where the Viterbi algorithm and a modified trellis incorporating a pertinent statistics of distorted patterns are used. The system works in a manner quite similar to our own human decision process. The trellis is so constructed that it can eliminate all the irrelevant pattern classes at the outset and leave only the most probable for its fimal decision, yielding a great economy of processing time and the accuracy of decision. The method was applied to recognition of handwritten English letters and Japanese Katakana's with success. The method is also universal and can be applied to any category of distorted pattems.

A method for the noiseless coding of binary memoryless sources when the symbol probabilities are unknown is investigated. Codes of long block length are constructed from truncated run-length codes. Though not universal, the codes are shown to achieve high efficiencies over a wide range of symbol probabilities. Several generalizations of the basic scheme are also presented. The schemes presented in this paper are particularly well-suited for facsimile coding.

A new method of soft-decision decoding of threshold decodable codes is presented. Excellent error performance, comparable to or better than that of other known practical schemes, is demonstrated by computer simulation and error analysis. The method is an approximate realization, without undue deterioration in performance, of the optimum {\em a posteriori} probability (APP) decoding and has a much simpler structure.

A noiseless encoding scheme is presented for sources with memory. The source is modeled by an ruth-order finite ergodic Markov process. A secondary source is derived which has as its symbol set the ordinal numbers of the symbol probabilities. The secondary source is approximately memoryless and has entropy smaller than that of the adjoint