Blind Image Watermarking for Localization and Restoration of Color Images

Abstract

Digital images have become easy to generate and share with tremendous growth in communication technology. Therefore, the threat of forgery and tampering in digital images has also been increased. This study proposes a blind fragile watermarking scheme for color images to provide efficient image tamper detection and self-recovery. A secret key based pseudo random binary sequence is used as a fragile watermark for tamper detection. Likewise, the recovery information is preserved in a randomized manner using a secret key. During embedding, each channel of the RGB image is divided into non-overlapping 2 x 4 size blocks. Each block is then watermarked using a LSB (least significant bit) replacement process in 9-base notation structure. The watermark sequence (i.e. 12-bit) for each block contains 6-bits from the fragile watermark and concatenated with the recovery information (i.e. 6 MSB (most significant bit) of block's mean value) of a different block. The experimental results confirm that the scheme is highly efficient to locate tampered region and recover the original image even in case of serious tampering. The scheme offers nearly 99% accurate tamper detection and significant recovery of tampered images (up to 80% tampering rate). Comparative results prove the significance and superiority of the scheme over existing schemes.