Abstract: The paper proposes a watermarking algorithm based on the adaptive modulation factor which parameterizes the number of the quantized coefficients of low and middle frequency (QCFMF) and the quantized DC coefficient. And in the non-blind detection algorithm, the DCT blocks using the number of QCFMF are classified into two sorts where the watermark is embedded at different strengths. The watermark is embedded by modifying the coefficient of low frequency in the blind detection algorithm. The experiments prove that the algorithms are strongly robust against JPEG attack

Key words: Adaptation; Quantization; QCFMF; Modulation factor

摘要： 提出了一种基于块自适应调节因子的水印算法。该因子以量化基础上的中低频系数的个数和直流系数为参数。并且按照统计的中低频系数的个数在非盲提取算法中将离散余弦变换（DCT）块分成两类并将水印以不同的强度嵌入。在盲提取算法中将水印嵌入低频系数中。实验证明本算法对JPEG 压缩等攻击有强的鲁棒性。

关键词: 自适应；量化；中低频系数；调节因子