Data hiding in encrypted images using transpose based reserving room before encryption & discrete wavelet transform

Abstract

Data hiding in encrypted images has the advantage of good privacy and security. This technique will be used for hiding a secret image inside a cover image using secret keys. In this paper, the Discrete Wavelet Transform method is used. (DWT) is any wavelet transform which is discretely sampled which captures both frequency and location information. The Discrete Wavelet Transform gives the excellent peak signal to noise ratio (PSNR) and less computation time The main advantage of using DWT transform is that the whole image would be processed as a single unit. It shows high robustness. The embedded secret image can be extracted with high visual quality. The patch can be used instead of pixels which result in large hiding room. Thus sparse coding is used, which is an approximation solution; the leading residual errors are encoded and self-embedded within the cover image. Hence no loss of data is observed because the learned dictionary is also embedded into the encrypted image and a large vacated room can be achieved and thus the data hider can embed more secret messages in the encrypted image. The PSNR of the method has been increased by 9.18 percent approximately.