Improving Fragileness of Semi-fragile Digital Watermarking by Using Hash Function

In this paper a novel method of semi-fragile digital watermarking is proposed based on both spatial and discrete wavelet transform domain.In order to improve the fragileness of watermark,the wavelet transform domain of the image is embedded with the Hash value based on the original image. The experimental results show that this algorithm is robust to JPEG compression.It can distinguish low-grade JPEG compression from the tampering of a small amount of pixels the original image especially.