| In recent years, as the continueous development of semiconductor technology, CMOS image sensors are used more and more widely in satellite remote sensing, visual surveillance, industrial inspection, military reconnaissance and medical diagnostics etc. because of their high integration, low cost, low power dissipation and simplification of design. With the shrinking size of integrated circuit technology, more and more image processing functions are integrated into CMOS image sensor, which makes it possible that digital watermarking technology combines with CMOS image sensor. In this paper, a watermarking algorithm in DCT domain for copyright protection of images and video is proposed and implemented.Based on analyzing development trend of CMOS image sensor and history of digital watermarking technology, this dissertation discusses the feasibility and necessity of combining digital watermarking technology with CMOS image sensor. This paper describes the basic principles of digital watermarking technology and the advantages of watermarking algorithm in DCT domain and proposes a blind watermarking algorithm which embeds watermark by modifying DCT coefficients. Fixed pattern noise of CMOS image sensor is used as key to scramble watermark in order to reach greater security. Verification show that the algorithm has good performance.Then FDCT, IDCT and proposed watermarking algorithm are implemented in hardware. Computation is greatly reduced by using the RCM structure and W.H.Chen fast algorithm. Multi-level pipeline structure is used to meet real-time data processing requirements. Watermark embedding module is embedded in FDCT circuit to reduce data latency. The circuit was simulated, logic synthesised, and verified on hardware verification platform. After debugging it can work properly that the watermarked image has a good quality and clear watermark can be extracted. The ASIC backend design is fabricated with Chartered 0.18μm CMOS process. |
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