A novel reversible watermarking scheme based on block energy difference for medical images

A novel reversible watermark scheme based on block energy difference (BED) for medical image is proposed in this letter. In the proposed scheme, cover image is firstly divided into some no-overlapping blocks, then integer wavelet transform (IWT) is used in every image block, as the energy of every block is different, watermark will be embedded in the low frequency subband of IWT based on BED. The novelty and advantage of the scheme lies in that the scheme achieves nearly automatic division of region of non-interest (RONI) and region of interest (ROI); it also has larger embedding capacity by using bidirectional histogram shifting than other watermarking scheme in frequency domain; in the end, without the help of location map of embedding, the proposed scheme achieves the reversibility, which is necessary for medical image. Experimental results verified the effectiveness of the scheme for medical images in the format of digital imaging and communications in medicine (DICOM).