中文摘要：

图像2LSB（Two Least Significant Bits，最低两位比特）替换隐写在各个位平面上的信息隐写可以是相互独立的，其隐写比率可以不同。文章基于带权隐秘图像检测方法的原理，给出了最低两位平面含隐写信息的带权隐秘图像模型，依据该模型构建了2LSB替换隐写比率估计方法。该方法首先运用现有LSB检测方法对次低位隐写比率做出了估计，然后依据文章建立的最低两位平面带权隐秘图像的模型，给出最低位隐写比率的估计。实验结果表明，本方法能较精确地估算出图像最低两位平面上各个位平面的隐写比率。

英文摘要：

The replacement steganography in each bit plane of 2LSB （Two Least Significant Bits） in digital images may be independent of each other and the embedding ratio in each bit plane can be different. Based on the principle of the weighted stego image, the weighted stegoimage model for 2LSB Replacement Steganography is given in this paper; and based on the model,the method to estimate the embedding ratio of 2LSB replacement steganography is constructed. Firstly, the method introduces existing LSB detection method to estimate the embedding ratio of hyper LSB after deleting the lowest bit plane, then estimation of the embedding ratio of LSB is given based on weighted stego image model for 2LSB Replacement Steganography. Experimental results show that the new method can estimate the embedding ratio in each bit plane of 2LSB with high precision.