Progressive transmission of vector-quantized images with security and fault-tolerance

The proposed method is an ((r1, ... , rk) , n)-threshold sharing system: n shares are created by the sharing system to replace the index file of a given quantized image. Security is achieved through the fact that interceptors cannot view the image if they intercept less than r1 shares. Fault-tolerance is also obtained because the VQ version of the image can be fully recovered using any rk shares. Each share is k / (r1 + r2 + ... + rk) times smaller than the index file. The VQ image can be recovered in a progressive manner, as long as the number of received shares reaches some preset threshold values. Key-words: vector quantization, image sharing, progressive reconstruction.