A lossless dictionary-based data compression technique has been proposed in this paper which is the modified form of compression technique based on optimality of LZW code (OLZW). The encoding process of proposed technique is almost similar with OLZW. Additionally a checking is performed to determine the dictionary is full or not before insertion of new entry into the dictionary. When the dictionary gets full, the least recently used dictionary phrase is deleted. A variant of the same is also proposed where no phrases of dictionary are deleted. But, phrases added to the dictionary are all the string formed by concatenation of previous match and prefix of current match including current match itself. Another technique is proposed which combines both the above proposed techniques. Comparisons of compression ratios are made among LZW, OLZW and proposed techniques which shows that the proposed techniques work well not only for small size files but also for large size files.
The image partitioning scheme in fractal image compression is one of the important aspect for enhancement of performance.In this paper, an adaptive quardtree partitioning scheme is proposed where the entire image is sub-divided recursively into four sub-images.The partitioning points are selected adaptively in a image context-dependent way instead of middle points of the image sides as in quardtree partitioning scheme.Biased successive differences of sum of pixel values of rows of the image are calculated to divide the image row-wise into two sub-images.Then, each sub-image is farther divided column-wise into two parts using biased successive differences of sum of pixel values of columns of the subimage.Then, a fractal image compression technique is proposed based on the proposed partitioning scheme.The comparison of the compression ratio and PSNR are done between fractal image compression with quardtree and proposed adaptive quardtree partitioning schemes.The comparison of the compression time between the same is also done.The fractal image compression with proposed partitioning scheme offers better compression rates most of the times with comparatively improved PSNR.But, the compression time of the fractal image compression with proposed partitioning scheme is much more than its counterpart.
In this paper a Modified Directional Weighted Cascaded-Mask Median (MDWCMM) filter has been proposed, which is based on three different sized cascaded filtering windows.The differences between the current pixel and its neighbors aligned with four main directions.A direction index is used for each edge aligned with a given direction.Then, the minimum of these four direction indexes is used for impulse detection for each and every masking window.Depending on the minimum direction indexes among the three windows one window is selected.The filtering is done on this selected window.Extensive simulations showed that the MDWCMM filter provides good performances of suppressing impulse with low noise level as well as for highly corrupted images from both gray level and colored benchmarked images.
In this paper, an approach has been made to provide security to digital song through embedding some secret information like singer name, album title, genre, etc on some precalculated portion of the song without changing its audible quality. Authenticating code is embedded as secrete information into original signal in the proposed technique. The embedded unique secret code is used to detect and identify the original song from similar available songs. A comparative study has been made with similar existing techniques and experimental results are also presented based on Microsoft WAVE (".wav") stereo sound files.
Confidence Based Learning (CBL) is a novel method in Teaching-Learning system where the process measures both the knowledge and confidence of a particular learner. In this paper a new framework has been proposed for Learning Objects (LO) suited for CBL. The proposal also takes care of the requirement for implementation including Learning Object Metadata (LOM). The novel framework proposed in this paper is used for prescribing learning content. The results show the progress in the performance of a typical learner through multiple iterations.
In this paper, a neural network guided secret key based technique for encryption (ANNRPMS) has been proposed using recursive positional modulo-2 substitution for online transmission of data/information through wireless communication. In this approach both the communicating networks receive an indistinguishable input vector, produce an output bit and are trained based on the output bit. The dynamics of the two networks and their weight vectors are found to a novel experience, where the demonstrate networks synchronize to an identical time dependent weight vectors. This observable fact has been used to form a secured variable length secret-key using a public channel. The length of the key depends on the number of input and output neurons. The original plain text is encrypted using recursive positional modulo-2 substitution technique. The secret key also fabricated through encryption process in a cascaded manner. This intermediate cipher text is again encrypted to form the final cipher text through chaining and cascaded xoring of identical weight vector with the identical length intermediate cipher text block. If size of the last block of intermediate cipher text is less than the size of the key then this block is kept unchanged. Receiver will use identical weight vector for performing deciphering process for getting the recursive positional modulo-2 substitution encrypted cipher text and secret key for decoding. A session key based transmission has also been proposed using 161-bit key format of 14 different segments. Parametric tests are done and results are compared in terms of Chi-Square test, response time in transmission with some existing classical techniques, which shows comparable results for the proposed system.
A Genetic Algorithm based color image authentication/data hiding technique through steganographic approach, termed as Genetic-Algorithm-based Steganography on Color Images (GASCI), has been proposed. Message/image is embedded on spatial domain onto rightmost three bits of each byte using 3×3 masks taken from source image in row major orde to generate stego image. New Generation, Crossover and Mutation are applied to enhance security level. Reverse process is followed during decoding. Various statistical parameters computed are compared with existing Yu et al. (2010) and Wang et al. (2001) which shows proposed GASCI obtained better results in terms of PSNR.
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