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Wyświetlanie 1-3 z 3
Tytuł:
Hybrid watermarking scheme based on singular value decomposition ghost imaging
Autorzy:
Wu, Jun-Yun
Huang, Wei-Liang
Wen, Ru-Hong
Gong, Li-Hua
Powiązania:
https://bibliotekanauki.pl/articles/1835818.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
digital watermarking
SVD ghost imaging
discrete wavelet transform
imperceptibility
Opis:
A hybrid watermarking algorithm with an optical watermark image based on singular value decomposition (SVD) ghost imaging is designed. Simultaneously, the blended watermarking algorithm is designed based on 4-level discrete wavelet transform (DWT), discrete cosine transform (DCT) and singular value decomposition (SVD). The 4-level diagonal sub-band image is obtained by performing 4-level two-dimensional wavelet transform on the original image, and the coefficient matrix is produced by applying the discrete cosine transform on the 4-level diagonal sub-band image. Then, three matrices are obtained by performing the singular value decomposition on the coefficient matrix. In addition, the optical watermark image is encrypted by an SVD ghost imaging system. The system could generate a secret key, and unauthorized users could not decrypt and reconstruct the original watermark image without this key. Later the encrypted watermark image is generated into the other three matrices by singular value decomposition. Afterwards, the encrypted watermark is embedded in the host image by mutual operation of different matrices in the algorithm. Simulation results validate the feasibility of the proposed hybrid watermarking scheme.
Źródło:
Optica Applicata; 2020, 50, 4; 633--647
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polarization dependence of stimulated Brillouin scattering-based switchable microwave photonic filter
Autorzy:
Gu, Jun
Wang, Fei
Lu, Youxi
Peng, Mengmeng
Shi, Lun
Kang, Wen
Huang, Jingxin
Powiązania:
https://bibliotekanauki.pl/articles/173837.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
microwave photonic filter
stimulated Brillouin scattering
polarization dependence
Opis:
We propose and experimentally demonstrate a switchable microwave photonic filter based on polarization dependence of stimulated Brillouin scattering (SBS). The continuous optical wave from a tunable laser source is split into two branches. One branch serves as the SBS pump source and another branch serves as the signal source which are interactional to generate the SBS effect in the dispersion-shifted fiber. Only by adjusting the polarization direction of pump light and signal light, a frequency response switched between bandpass and notch filtering shape can be obtained.
Źródło:
Optica Applicata; 2019, 49, 1; 5-11
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photonic generation of broadly tunable radio-frequency signal using a reflective semiconductor optical amplifier
Autorzy:
Lu, Youxi
Wang, Fei
Gu, Jun
Shi, Lun
Peng, Mengmeng
Huang, Jingxin
Kang, Wen
Powiązania:
https://bibliotekanauki.pl/articles/173479.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
radio frequency signal generation
semiconductor optical amplifiers
four-wave mixing
Opis:
A novel scheme for photonic generation of broadly tunable radio frequency signal using a reflective semiconductor optical amplifier (RSOA) is demonstrated. A continuous wave emitted from the laser diode is modulated by a Mach–Zehnder modulator, then the modulated optical carrier is injected into the RSOA. Due to the four-wave mixing effect in the RSOA, the limited frequency components of the modulated signal are expanded, which directly lead to the generation of a wide frequency comb. Two optical tunable bandpass filters are parallelly connected to select the desired sidebands, which are launched into a photodetector or photomixer to generate radio frequency signal by beating. Using the proposed method, the bandwidth of generated radio frequency signal can range from 20 to 300 GHz.
Źródło:
Optica Applicata; 2019, 49, 1; 27-36
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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