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Spread-spectrum steganographic (SSIS) method offers high payload and robustness to additive noise in transmission channel but the visual quality of image is distorted and exact data recovery may not be satisfied. DCT-domain message hiding based steganographic techniques provide high image imperceptibility and exact data recovery in absence of noise. In this paper, we combined the best of SSIS and...
This paper presents a compression algorithm for dynamic data, the size of which keeps on increasing rapidly. It is a memory efficient data compression technique comprising of a block approach that keeps the data in compressed form as long as possible and enables the data to be appended to the already compressed text. The algorithm requires only a minimal decompression for supporting update of data...
We present two results related to the computational complexity of lossy compression. The first result shows that for a memoryless source Ps with rate-distortion function R(D), the rate-distortion pair (R(D) + gamma, D + isin) can be achieved with constant decoding time per symbol and encoding time per symbol proportional to C1(gamma)isin-C2(gamma). The second results establishes that for any given...
This paper presents a compression algorithm for dynamic data, the size of which keeps on increasing frequently. It is an efficient data compression technique comprising of a block approach that keeps the data in compressed form as long as possible and enables the data to be appended to the already compressed text. The approach requires only a minimal decompression for supporting update of data. The...
We propose a scheme to implement lossy data compression for discrete equiprobable sources using block codes based on sparse matrices. We prove asymptotic optimality of the codes for a Hamming distortion criterion. We also present a sub-optimal decoding algorithm, which has near optimal performance for moderate blocklengths.
A number of image compression systems have been developed to save storage space and transmission bandwidth. The field of image compression has witnessed a lot of research on improving JPEG or evolving a codec with better performance. In the JPEG standard, run length encoding is used to code the string of zeros resulting from crude quantization of AC coefficients. In this paper we propose modified...
We propose measures for compressed data structures, in which space usage is measured in a data-aware manner. In particular, we consider the fundamental dictionary problem on set data, where the task is to construct a data structure to represent a set S of n items out of a universe U = {0,..., u $1} and support various queries on S. We use a well-known data-aware measure for set data called gap to...
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