Natural speckle-based watermarking with random-like illuminated decoding

Abstract

We propose an optical watermarking method based on a natural speckle pattern. In the watermarking process, the watermark information is embedded into the natural speckle pattern. Then the random-like watermarked image is generated with the proposed grayscale reordering algorithm. During the extraction procedure, the watermarked image is projected to the natural speckle pattern as illumination. Subsequently, they are incoherently superimposed to extract the watermark information directly by human vision. Optical experiments and a hypothesis test are conducted to demonstrate the proposed method with high reliability, imperceptibility and robustness. The proposed method is the first watermarking method utilizing the natural diffuser as the core element in encoding and decoding.

Speckle patterns formed by broadband terahertz radiation and their applications for ghost imaging

“…Speckle pattern formation is a phenomenon that occurs in situations where a coherent light reflects or transmits through a rough surface or a turbid medium 1 , 2 . Despite the fact that the occurrence of speckle-noise can affect negatively for some imaging techniques (e. g. optical coherence tomography and LIDAR technologies), there are fields in which usage of speckle patterns can be very promising: it applied for image retrieving in speckle metrology 3 , single pixel imaging 4 , for ghost imaging 5 – 8 , cryptography technique 9 etc. In turn, terahertz (THz) radiation, due to the optical properties of various materials in this frequency range, as well as the features of individual properties of the radiation itself, is becoming more popular in quality control systems 10 – 12 , safety 13 – 16 and biomedicine application 17 – 19 , communication 20 – 23 .…”

Speckle Patterns formed by Broadband Terahertz Radiation and their Applications for Ghost Imaging

“…Speckle pattern formation is a phenomenon that occurs in situations where a coherent light reflects or transmits through a rough surface or a turbid medium 1,2 . Despite the fact that the occurrence of speckle-noise can affect negatively for some imaging techniques (e. g. optical coherence tomography and LIDAR technologies), there are fields in which usage of speckle patterns can be very promising: it applied for image retrieving in speckle metrology 3 , single pixel imaging 4 , for ghost imaging [5][6][7][8] , cryptography technique 9 etc. In turn, terahertz (THz) radiation, due to the optical properties of various materials in this frequency range, as well as the features of individual properties of the radiation itself, is becoming more popular in quality control systems [10][11][12] , safety [13][14][15][16] and biomedicine application [17][18][19] , communication [20][21][22][23] .…”