A PARTIAL ENCRYTION METHODS FOR DIGITAL HOLOGRAMS

摘要

A partial encryption method for digital holograms is provided to encrypt only a DC coefficient having the highest energy concentration in a DCT domain and encrypt a domain higher than 4 level after 6 level DWT, thereby effectively hiding a recovered object. A fringe pattern is divided by a bit plane. The divided fringe pattern is recovered. HoloVision of a simulation tool is used for the recovered image. The fringe pattern is divided for analysis in a frequency domain. And DWT(Discrete Wavelet Transform) and GDCT(Global Discrete Cosine Transform) are applied to the divided fringe pattern. The DWT uses PDWT (Packetized DWT) and MDWT (Mallat-tree DWT) modes. Wavelet conversion of a hybrid type is used according to a result. The MDWT is used for JPEG2000. The MDWT is a converting method for dividing a low frequency signal and concentrating energy on a low frequency coefficient. A frequency characteristic of the fringe pattern includes noise. A PDWT method is parallel used. The PDWT divides a sub band by multi-resolution.