基于菱形编码和修改量化表的DCT域图像隐写

Image Steganography Based on Diamond Encoding and Quantization Table Modification in DCT Domain

为了提高离散余弦变换(DCT)域隐写的嵌入容量,提出一种基于菱形编码和修改量化表的DCT域图像隐写.首先将载体图像进行8×8的DCT变换后,对变换得到的DCT系数采用修改的8×8量化表进行量化,从而提高了嵌入容量和载密图像的视觉质量.同时通过改进的菱形编码将8进制的秘密信息嵌入到载体图像量化DCT系数的中频部分,从而进一步提高了嵌入容量.实验结果表明:该隐写算法不但与JPEG压缩标准兼容,而且有效地提高了嵌入容量.

In order to improve embedding capacity of steganography in discrete cosine transform （DCT） Domain, a new image steganography is proposed based on the diamond encoding and quantization table modification. Firstly, the carrier image is transformed by 8×8 block DCT, then the DCT coefficients are quantized using the modified 8×8 quantification table, which increases the embedding capacity and steno-image visual quality. The 8-ary secret image data are embedded in the middle-band of frequency of the carrier image＇s DCT coefficients using the modified diamond encoding, then the embedding capacity can thus be further improved. The experimental results show that the proposed method not only maintains good imperceptibility of image after embedding large amount of secret message, but also effectively improves the embedding capacity as well.