Research On Information Hiding Algorithm Of Image And DEM Data

Information hiding technique is having a great influence on the national economy and safety for each nation,which has become a hot research field in recent years.Some problems of digital watermarking and information disguising,which are branches of the information hiding,have been studied in this paper.The main work of the proposed are as follows:A blind lossless watermarking method for digital elevation mode(DEM) data via modifying the histogram of the DEM data is presented in this paper.This algorithm can recover the original DEM data without any distortion from the marked data after the watermarking has been extracted,which owns good value in the economy.The computational complexity of our method is low,which is feasible in dealing with the DEM data of floating-point precision.We can get high PSNR(average 42dB) of the marked data as ensure the high embedding capacity(≥48.8kb), so the original shape and relief of the terrain has kept after embedding the watermarking.For the copyright protection of the digital images,a new asymmetric robust watermarking method is proposed based on the feature subspace projection by the lifting-wavelet or the Contourlet transformation.Embedding matrix(private key) and detecting matrix(public key) are constructed differently,where the embedding matrix is kept secret while the detecting matrix is public.At the same time,the watermarking and the embedding matrix are independent on the host images.Anyone can access to the detection matrix and use it to verify whether an image is watermarked or not.However,the attacker can neither infer the embedding key from the detecting key nor remove or counterfeit the watermarking.Robust subspace as watermarking space is obtained by the lifting-wavelet or the Contourlet transformation.Then,watermarking is embedded in the robust subspace using embedding matrix.High detection probability and low false alarm probability of the proposed methods have been proved.The stimulations show that our methods are robust to many attacks,such as projection attack,noising,rotation,clipping, scaling,and JPEG compression etc.A novel information disguising method based on empirical mode decomposition is proposed in this paper.The seeds are the input of the SHA-256hash function and the output of the hash function is the pseudorandom sequence.Then we decompose the expanded pseudorandom sequence via EMD to get DEM data for disguising.The disguised DEM data have high vision fraudulence.The seeds and the copyright are encoded and then embedded in the disguised DEM data via reversible watermark.This algorithm can recover the disguised DEM data without any distortion from the marked data after the watermark has been extracted.Secret DEM data can be recovered via the key.This algorithm can realize multilevel management of consumer's purview.