Copyright protection scheme for color images using extended visual cryptography

Most of the existing visual cryptography based copyright protection schemes create random looking shares which can create suspicion of some secret information being shared. In order to handle this issue, a copyright protection scheme based on curvelet transform and extended visual cryptography is proposed for color images. Robustness of the scheme against various attacks is achieved by using inter-layer low and middle frequency coefficients obtained by applying discrete curvelet transform on R, G, and B components of host image. The curvelet inter-layer coefficients are used to create a master share. This master share and the watermark are used to create the ownership share by using the codebook. XOR-superimposition of master and ownership shares retrieve the watermark to prove the copyright. Security of the scheme is achieved by creating meaningful ownership shares; and by using Baker's Map for scrambling watermark and transformed host image. The scheme is robust to withstand several image processing attacks as well as provides better imperceptibility. Effectiveness of the scheme is shown by comparing it with the existing copyright protection schemes.