Halftoning Based Visual Secret Sharing (Vss)

Definition:In Visual Secret Sharing based on halftoning, the continuous-tone image is first transformed into a halftone image, and then the VSS is applied.

Since VSS-schemes require binary inputs [1], [2], the continuous-tone image is first transformed into a halftone image using the density of the net dots to simulate the intensity levels [3]. In the sequence, the halftone version of the secret image is encryptedinto the n shares using the conventional (k, n) visual cryptography based encryption process. The secret image is visually revealed if at least k shares are available for decryption and stacked together on an overhead projector or specialized display.

Due to the nature of visual cryptography, and the expansion and contrast properties of (k,n )-VSS schemes, both binary (conventional) and halftoning-based VSS schemes usually produce shares and decrypted images with expanded dimensions compared to those of the original input (secret) image. In addition, VSS schemes introduce...