| As the mobile Internet, multimedia and hardware manufacturing technology develop, intellectual property protection is becoming a problem on your smartphone. Because of the CPU computing power, memory capacity and energy consumption restrictions, we can not apply huge computational watermarking algorithms to smartphones directly. It is resulting in the lack of a convenient and effective way of protecting intellectual property rights on the smartphones.To find a solution to the above problem, this paper gives a summary of the basic knowledge of digital watermarking, including the concept, classification, application, basic framework, quality evaluation of digital watermarking, and introduces some phone watermarking algorithm has been proposed for reference firstly.Because the watermarking algorithm based on mean gray value and some DCT watermarking algorithm which calculate a small amount of DCT coefficients has lower time complexity and high robustness, we propose two blind watermarking algorithm for smartphones color image.The first is a spatial domain watermarking algorithm based on gray value quantization of blocks, because the original watermark "divided" into four similar small watermarks before embedding into the cover image and replace the seriously damaged area with slightly damaged area in the extraction phase. Experiments have shown that the algorithm has both good anti-JPEG compression ability and good anti-cutting capacity.The second is DCT domain watermarking algorithm, and watermark is embedded by adjusting the size relationship between the two selected DCT coefficients. It determines the amount of the change of the two selected DCT coefficients based on the JPEG quantization table in order to reduce the impact on the visual quality of the image. According to the linear relationship between the increments of the different space, the algorithm can avoid the conversion between RGB space and YCrCb space and spatial domain and DCT domains. And owing to the equation coefficients stored in advance, the coefficients won’t be calculated repeatedly. Experiments have shown the watermark survived various attacks such as JPEG compression, noise,3×3 2D filtering, and different image manipulation algorithms, at the same time the algorithm also has a very low time complexity. |
