Perceptual cryptography on SPIHT compressed images or videos

Perceptual cryptography encrypts multimedia data in compression domain and causes some degradation to the decoded data. If customers are interested in the multimedia data, they will pay for the one of higher quality. In this paper, a perceptual cryptography on SPIHT encoded image or video is presented. By confusing different number of wavelet coefficients and encrypting different number of coefficients' signs, the images or videos can be degraded to different degree. Its encryption strength can be adjusted according to certain quality factor, it supports direct bit-rate control, and is of low cost, which makes it suitable for multimedia applications with real-time operation requirement, such as video conference, multimedia network, mobile multimedia and soon.