Chirp-Fourier变换域的水印算法

提出一种新的修正离散Chirp-Fourier变换(MDCFT)域盲水印方案，其包括水印嵌入和水印检测2部分。该方案把Chirp水印信息嵌入图像经二维修正离散Chirp-Fourier变换后的系数上，对其进行反变换，得到含水印图像，利用二维MDCFT对水印信息进行盲检测。由于DCFT可通过FFT实现，与其他时/频域水印算法相比，其实现更为方便。仿真试验表明，该算法透明性好，检测速度快，植入的数字水印对高斯噪声、剪裁、旋转和JPEG有损压缩等图像处理具有较强的鲁棒性。

Watermark Algorithm in Chirp-Fourier Transform Domain

A novel blind watermark algorithm in Modified Discrete Chirp-Fourier Transform(MDCFT) domain is proposed, which includes watermark embedding and watermark detecting. The two-dimensional chirp signal is embedded in MDCFT domain by inversing MDCFT to obtain the watermarked image. The watermark is detected by MDCFT. DCFT can be implemented by FFT, so the algorithm is simple in computation and easy in implementation comparing with other watermark algorithms in time-frequency domain. The experimental results show that the algorithms can make the watermark invisible perpetually, and are also robust to some common image processing, such as adding Gauss noise, cropping, rotating and JPEG compressing, etc.