关键词: 抖动量化调制, 小波变换系数, 峰值信噪比, 量化步长, 量化误差, 量化系数

Abstract: Quantization step is a key parameter in quantization modulation method, but now there is no theoretical method to decide its value. To solve this problem, a quantitative estimation method of quantization step based on Peak Signal-to-Noise Ratio (PSNR) was proposed. In this method, dither quantization modulation method was chosen as research object, and wavelet coefficients were regarded as quantization coefficients. According to the distribution of quantization error, it firstly gave an estimating quantization error method based on quantization step. Then it deduced the quantitative relationship equation of quantization step, watermark sequence length and PSNR on the basis of some properties of wavelet transform. The experimental results show that PSNR values calculated through quantitative equation are in good agreement with those obtained from experiments when the values of their quantization step are the same. It demonstrates that the deduced quantitative relationship equations are accurate.

Key words: dither quantization modulation, wavelet transform coefficient, Peak Signal-to-Noise Ratio (PSNR), quantization step, quantization error, quantization coefficient