Abstract:

Based on difference expansion and difference shifting a novel lossless data hiding algorithm is proposed. A sequence of pixels with grey levels is obtained by scanning the image in a given order. Then the difference of each adjacent pixel-pair is calculated. If the difference is larger than K-1 (K is a positive integer chosen by the user based on the embedding capacity), it is shifted right; if the difference is smaller than-K, it is shift left; if the difference falls between -K and K-1, it is used to embed the data. At the same time the distortion caused by expansion is uniformly distributed to the two pixels, which keeps the high quality of the image. Experimental results demonstrate that the proposed scheme can embed a larger payload while keeping the same Peak Signal-to-Noise Ratio (PSNR).

Key words: computer application, lossless data hiding, difference expansion, difference shifting