In this paper, a recoverable image content authentication algorithm based on digital watermarking is proposed. The host image was first divided into equal-sized blocks and then analyzed to obtain two pieces of information: one for tamper detection and the other for image recovery. For tamper detection, the relations between image blocks were established in order to discourage an adversary’s attempt to alter the image. In addition, the authentication system was designed in such a manner that it is very insensitive to common image processing operations. For image recovery, in order to achieve a better recovery result, an image block with more complex contents (referred to as an edge block) was further divided into sub-blocks. A non-edge block, if tampered with, would be recovered using its pixel intensity mean embedded previously, whereas an edge block would be reconstructed by recovering the intensities of its sub-blocks. Due to the different recovery strategies for edge and non-edge blocks, the quality of the reconstructed image is more satisfactory. Our experiments demonstrated that the proposed algorithm is able not only to detect tampered areas but also to recover the tampered blocks.