Quadtree Compression Based Method for High Capacity Reversible Data Hiding in Encrypted JPEG Images

The existing methods of reversible data hiding in encrypted JPEG images vacates space for data hiding after encrypting the image. This results in information loss as entropy in encrypted images is more. The complexity of image reconstruction is higher in such cases. The proposed method therefore finds space for data hiding before image encryption using the method of quadtree compression. Then the image is encrypted using RC4 encryption algorithm. The secret data bits are embedded into the MSB bit of pixels obtained after quadtree compression with the help of data hiding key. The data extraction and image recovery is made separable at the receiver side such that the secret data can be extracted without knowing the image contents. Original pixel restoration is done using prediction error method. The experimental results show that the proposed method is able to achieve better data hiding capacity and recovered image quality within an acceptable complexity range.