Joint Cover-Selection and Payload-Allocation by Steganographic Distortion Optimization

This letter proposes a batch steganographic method, which combines cover-selection and payload-allocation by steganographic distortion optimization. We first proved that with the value of payload increasing, the first-order derivative of steganographic distortion of a single cover is monotonically increasing. Then, we deduced that the first-order derivative of steganographic distortion of covers that selected from a given set should be equal if the total steganographic distortion of the corresponding selected covers is minimal. Finally, an algorithm was designed to combine cover-selection and payload-allocation, so that the optimal stego-covers can be obtained. Experiment results show that the undetectability is obviously improved when using the proposed steganographic method.