Watermarking algorithm for color two-dimensional code based on DCT-SVD

Abstract

In this paper, a new watermarking method for color QR code that has more digital watermarking capacity and robustness is presented. The QR code has a backdrop of green as the original image, watermark is the pretreated QR code information. When embedding watermark, the information is encoded into color QR code to extract its backdrop. And the watermark takes encryption algorithm based on logistic chaotic sequence to improve safety. The encoded and encrypted watermark is embedded into luminance coefficients from the sixty pixels with quantized DCT (Discrete Cosine Transform) block matrix and SVD (Singular Values Decomposition). Compared with the existing watermarking algorithm, it not only keeps fast scanning characteristics of QR codes, but also has better embedding capacity and stronger robustness against rotation, shearing, noise, and filter. It can be used as a new method of copyright protection based on color two-dimensional code.