Capacity improvement in digital watermarking using QCM scheme
نویسنده
چکیده
Quadrature Carrier Multiplexing (QCM) allows simultaneous transmission of two message signals over the same bandwidth using quadrature carriers of the same frequency. This principle is used in this work to improve embedding capacity in digital image watermarking using wavelet transforms. Biorthogonal wavelet filters are used to design Hilbert transform (HT) pair and symmetric filter coefficients reduce computation cost significantly in watermarking. Hilbert transform (HT) pair decompose the cover image in two quadrature directions so that the effect of inter symbol interference (ISI) is reduced to the minimum level and embedding capacity is increased two times although there occurs almost no degradation in robustness performance. Spread spectrum (SS) modulation technique further improves robustness performance and spreading codes are designed based on the selection of wavelet sub bands so that host signal interference is reduced significantly. Experiment results show that watermark decoding from both the decompositions are affected in the similar fashion over a wide range of signal degradation. K eywords: Spread Spectrum watermarking, wavelet transformation,M -ary modulation, lossy compression.
منابع مشابه
A Modified Digital Image Watermarking Scheme Based on Nonnegative Matrix Factorization
This paper presents a modified digital image watermarking method based on nonnegative matrix factorization. Firstly, host image is factorized to the product of three nonnegative matrices. Then, the centric matrix is transferred to discrete cosine transform domain. Watermark is embedded in low frequency band of this matrix and next, the reverse of the transform is computed. Finally, watermarked ...
متن کاملA Modified Digital Image Watermarking Scheme Based on Nonnegative Matrix Factorization
This paper presents a modified digital image watermarking method based on nonnegative matrix factorization. Firstly, host image is factorized to the product of three nonnegative matrices. Then, the centric matrix is transferred to discrete cosine transform domain. Watermark is embedded in low frequency band of this matrix and next, the reverse of the transform is computed. Finally, watermarked ...
متن کاملWavelet Based Hilbert Transform with Digital Design and Application to QCM-SS Watermarking
In recent time, wavelet transforms are used extensively for efficient storage, transmission and representation of multimedia signals. Hilbert transform pairs of wavelets is the basic unit of many wavelet theories such as complex filter banks, complex wavelet and phaselet etc. Moreover, Hilbert transform finds various applications in communications and signal processing such as generation of sin...
متن کاملA Robust Digital Image Watermarking Scheme Based on DWT
In this paper a wavelet-based logo watermarking scheme is presented. The logo watermark is embedded into all sub-blocks of the LLn sub-band of the transformed host image, using quantization technique. Extracted logos from all sub-blocks are merged to make the extracted watermark from distorted watermarked image. Knowing the quantization step-size, dimensions of logo and the level of wavelet tra...
متن کاملA Robust Digital Image Watermarking Scheme Based on DWT
In this paper a wavelet-based logo watermarking scheme is presented. The logo watermark is embedded into all sub-blocks of the LLn sub-band of the transformed host image, using quantization technique. Extracted logos from all sub-blocks are merged to make the extracted watermark from distorted watermarked image. Knowing the quantization step-size, dimensions of logo and the level of wavelet tra...
متن کامل