A Text Image Watermarking Algorithm Based on Image Enhancement

Digital watermarking technology is adequate for copyright protection and content authentication. There needs to be more research on the watermarking algorithm after printing and scanning. Aiming at the problem that existing anti-print scanning text image watermarking algorithms cannot take into account the invisibility and robustness of the watermark, an anti-print scanning watermarking algorithm suitable for text images is proposed. This algorithm first performs a series of image enhancement preprocessing operations on the printed scanned image to eliminate the interference of incorrect bit information on watermark embedding and then uses a combination of Discrete Wavelet Transform (DWT)-Singular Value Decomposition (SVD) to embed the watermark. Experiments show that the average Normalized Correlation (NC) of the watermark extracted by this algorithm against attacks such as Joint Photographic Experts Group (JPEG) compression, JPEG2000 compression, and print scanning is above 0.93. Especially, the average NC of the watermark extracted after print scanning attacks is greater than 0.964, and the average Bit Error Ratio (BER) is 5.15%. This indicates that this algorithm has strong resistance to various attacks and print scanning attacks and can better take into account the invisibility of the watermark.